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SOMATOM Sessions
The Difference in Computed Tomography
Issue no. 20 / June 2007
Stanford-Edition
June 13th–16th, 2007
Cover Story
Dual Source CT Reshapes
Clinical Imaging
Page 4
News
syngo CT Oncology
Page 14
Clinical
Outcomes
Acute Care: New Insight
Into Kidney Stone Detection and Treatment With
Spiral Dual Energy
Page 44
Science
Half-Scan vs. Multi-Segment Reconstruction for
CT Coronary Angiography
Page 54
Education &
Events
New: Cardiac CT Poster
Page 60
Editor’s Letter
André Hartung,
Vice President Marketing
and Sales.
Dear Reader,
To provide the world’s population with
the best possible, economically solid,
medical care is the challenge faced by all
healthcare systems today. This places the
responsibility squarely upon medical doctors, clinics and other healthcare institutions to cost-efficiently provide faster and
more reliable diagnoses and treatments.
Given the pressure to constantly reduce
costs, it is no longer practical to expect
the investment in high-end imaging
equipment to be amortized from imaging
patients alone: the entire clinical process,
whether in hospitals or practices, must
be accelerated while improving healthcare quality. In everyday practice, this
means reducing the time required from
”suspicion” to diagnosis, reducing the
number of examinations and shortening
the length of hospital stays – all improvements that can be ideally supplemented
by computed tomography (CT). CT offers
an incredibly broad spectrum of examinations, is widely available, – usually
around the clock – with minimum personnel requirements. New clinical applications and ease-of-use promise a bright
future for CT in improved patient care
while further reducing costs.
The recent introduction of Dual Source
CT with the SOMATOM® Definition represents a break-through in the entire medical imaging industry. Beta-blockers are no
longer necessary for heart CT scans and
no patient must ever again be turned
away. A major benefit is the ability to
avoid unnecessary and expensive diagnostic heart catheterization procedures.
syngo® Dual Energy (DE) transforms
black and white anatomical imaging into
highly functional color imaging, making
many pathologies visible that were previously not detectable – such as, for only
one example, gout related urate deposits.
The probability that syngo DE will soon
become a standard CT application is
obvious.
The trend is clearly visible today towards
automatically processing large data volume rather than manually viewing and
post-processing layers and slices. This
procedure is perhaps best illustrated by
syngo CT Oncology**, an application that
supports the complete diagnostic workflow. Rough approximations of tumor
dimensions are now replaced by precise
measurements. Because oncology accounts for approximately 60% of CT use*,
improvements in this area will speed up
and simplify routine throughput in many
practices.
The necessity for data to be available to
many departments within a medical
facility, as well as to external locations,
has been solved by Siemens with the
introduction of syngo WebSpace. 3D data
can now be called up for viewing and
processing wherever and whenever it is
needed - even from a home PC or a laptop while traveling. Instead of purchasing
and installing multiple workstations,
medical facilities today can install an imaging center with an application server
that is constantly updated and simultaneously available for up to 20 viewers at all
times. The savings in both investment
and expensive professional time are considerable.
It has always been Siemens‘ ambition to
establish sweeping, innovative megatrends and consistently follow these up
with unique products.
As you will read in this issue of the
SOMATOM Sessions, we are not relaxing
our dedication to this principle and to
providing you with new, intelligent solutions that make a positive difference in
all your professional activities.
André Hartung
* Results may vary. Data on file.
** Pending 510(k): The information about this
product is being provided for planning purposes
only. This product is pending 510(k) review, and
is not yet commercially available in the U.S.
Cover Page: Volume rendered image of a dual energy examination of the hands of an adult patient with acute gout. With the dual energy information, deposits of uric
acid can be detected within the tophi. Areas of active inflammation additionally show an increased contrast enhancement. By Drs. T. Johnson, S. Weckbach, H. Kellner,
M. Reiser and C. Becker, University of Munich – Grosshadern, Munich/Germany. Cf. ‘Molecular Imaging of Gout‘ (Arthritis & Rheumatism; in press)
2 SOMATOM Sessions · June 2007 · www.siemens.com/medical-magazine
Content
Cover Story
4
Dual Source CT Reshapes Clinical Imaging
News
10 Maximum CT Capabilities in Minimum Space
14 Fully Automated Tumor Tracking With syngo CT Oncology
16 syngo Circulation – Siemens Scientifically Validated
Cardiac CT Software
Business
17 Flexibility for the Future – Now
22 Big Progress for a Small Clinic
25 Cardiac CT Takes Off
4
Dual Energy For Clinical Routine
Clinical Outcomes
Cardiovascular:
30 Heterotopic Heart Transplant With Arrhythmic
Heart Rate of 45 –125 bpm
32 Reliable In-Stent Lumen Visualization With
Dual Source CT Coronary Angiography
34 Abdominal CTA With Direct Dual Energy Bone Subtraction
Oncology:
36 New: syngo CT Oncology
38 Improved Evaluation and Follow-up of Routine
Diagnostic Oncology Exams With syngo CT Oncology
Neurology:
40 Utilizing the SOMATOM Emotion 16 for a Neuro DSA CTA
Evaluation of a Suspected PICA Aneurysm
25
Cardiac CT Takes Off
Acute Care:
42 Dual Source CT Triple Rule Out Without ß-Blocker
44 New Insight Into Kidney Stone Detection and Characterization
With Spiral Dual Energy
Science
46 Detecting Coronary Atherosclerosis by DSCT Images With
Color Maps
48 Coronary CT Angiography With DSCT – Implications for
Contrast Media Delivery
52 Nefertiti´s Bust – An Inside View
54 Half-Scan vs. Multi-Segment Reconstruction for CT Coronary
Angiography
Education & Events
32
DSCT Coronary Angiography
59 CT Life Card: Clinical Education at Your CT Workplace /
E-Logbook: Eliminate Cumbersome Paperwork
60 New: Cardiac CT Poster / New: CTA Interpretation Workshops
61 Free 90 Day Trial Licenses for Clinical Applications /
Frequently Asked Questions
62 E-Newsletter / Upcoming Events & Courses
63 Imprint
SOMATOM Sessions · June 2007 · www.siemens.com/medical-magazine
3
Cover Story
Dual Source CT Reshapes
Clinical Imaging
When dual source technology burst on the scene in 2005, it did more
than change the look of CT. It changed the future of medicine, not only surmounting critical barriers in cardiac imaging, but also introducing an entirely
new way of characterizing body tissues using dual energy techniques.
By Catherine Carrington
From the start, it was clear that cardiac
imaging would win big with Dual Source
CT. With a temporal resolution of just
83 milliseconds, Siemens’ SOMATOM®
Definition Dual Source CT scanner can
freeze cardiac motion in even the most
challenging patients. Nowhere is this
more important than in the emergency
department (ED), where the Definition is
revolutionizing the diagnosis of patients
with acute chest pain. “Dual Source CT
has overcome many of the obstacles we
had with the 64-slice scanner,” says
Michael Gallagher, MD, a cardiologist at
William Beaumont Hospital in Royal Oak,
Michigan. “We have fewer artifacts, less
dependency on heart rate, less dependency on the regularity of the heart
rhythm, and overall, a much higher percentage of diagnostic scans.”
Gallagher has been deeply involved
in research into the role of multislice CT
for the evaluation of patients with acute
chest pain. In a study in the February
2007 issue of the Annals of Emergency
Medicine, he showed that 64-slice CT was
at least as accurate as conventional stress
nuclear testing for determining the cause
of chest pain in low-risk patients, if not
more so. A negative CT scan was 99 % accurate for eliminating coronary artery
disease as the cause of chest pain, while
a negative nuclear stress test was 97 %
accurate*.
1
1 Large aneurysm of ascending aorta.
*Results may vary. Data on file.
Cover Story
No Need for Beta-Blockers
The SOMATOM Definition Dual Source CT
is a further leap forward. “Image quality
on the Dual Source CT is excellent. In
fact, it’s as good without the use of betablockers as it was on the 64-slice CT when
patients were premedicated with betablockers,” Gallagher says. The ability to
eliminate beta-blockers in most patients
has had an enormous impact on the evaluation of acute chest pain, expanding
the range of patients who are eligible for
CT scanning, streamlining patient preparation in both the ED and the CT suite,
speeding the time to diagnosis, freeing
up resources for additional patients, and
cutting healthcare costs.
In the past, as many as 20 % of patients
simply could not have a cardiac CT scan,
as they could not safely take beta-blockers to slow the heart rate to 65 to 70
beats per minute, a rate necessary to
achieve high-quality images on a 64-slice
CT scanner. This group includes, among
others, patients with asthma or left ventricular dysfunction, and those who have
used cocaine within the previous few
days. With the Definition, such patients
can be routinely scanned without the
need for beta-blockers.
At the University of Pennsylvania, for
example, patients with a heart rate as high
as 85 beats per minute undergo cardiac
CT scanning without beta-blockers. In the
past, 70 % of patients were given oral
beta-blockers and 20 % needed additional
intravenous beta-blockers; today very few
patients take any medication to slow the
heart rate.
“The Dual Source CT has dramatically reduced the percentage of patients getting
beta-blockers to about 10 %,” says Harold
Litt, MD, Chief of Cardiovascular Imaging
and an Assistant Professor of Radiology
and Medicine at the University of Pennsylvania in Philadelphia. “And it’s likely
that most of those patients are getting
beta-blockers not because of the CT scan,
but because their care in the emergency
department dictates it. We’re not giving
any intravenous beta-blockers on the CT
table.”
William Beaumont Hospital also now
eschews beta-blockers until the heart rate
exceeds 85 beats per minute. They have
successfully stretched that limit, however.
“It is important to note that we have
scanned patients with heart rates of 90,
100 and 110 beats per minute on the
Definition, with very positive results,”
Gallagher says.
The ability to eliminate beta-blockers from
the scan protocol has more than clinical
benefits. It streamlines patient diagnosis
from beginning to end, saving both time
and money.
Shorter Stays, Reduced Costs
Researchers at William Beaumont published a groundbreaking study in the
February 27, 2007, issue of the Journal
of the American College of Cardiology.
It showed that with a standard nuclear
stress testing protocol, it took more than
15 hours, on average, to reach a diagnosis
in low-risk patients with acute chest pain.
The use of 64-slice CT cut that time to
3.4 hours.
“The standard work-up can be long
and complicated. Patients can spend an
entire day in the emergency room,” says
Gilbert L. Raff, MD, director of the Minestrelli Center for Advanced Cardiovascular
Imaging at William Beaumont. “This is
the first study in which emergency physicians used CT to make clinical decisions
about the management of patients with
chest pain. It represents a major change.”
Today, the Definition is speeding patient
care still more. Much of the improvement
takes place even before the patient arrives
in the CT suite. “There used to be a lot of
phone calls back and forth between the
2
2 Triple rule-out examination with artifact-free visualization
of right and left coronary arteries and aortic arch.
5
Cover Story
emergency physician and the radiologist,”
says Litt. “‘Is the patient eligible for the
study? Can he be given beta-blockers? Is
the heart rate response adequate? Does
the patient need intravenous beta-blockers? Will a nurse need to go to radiology
to monitor the patient?’ The Definition
has made things much less complicated
because we don’t have to talk about those
issues now.”
In addition, waiting for the patient’s heart
rate to slow to the target range typically
took an hour or more. Today, if the electrocardiogram is normal and the first set
of cardiac enzymes shows no signs of a
heart attack, the patient can immediately
go for CT scanning. If the second set of
cardiac enzymes is normal, the patient
can be safely discharged home, potentially
within only a few hours of arriving at
the ED.
Although neither William Beaumont nor
the University of Pennsylvania has
tracked the improvement in time from
patient arrival in the ED to the initiation
of scanning, both Litt and Gallagher
believe the savings have been substantial.
In addition, Gallagher estimates that it
now takes only about two hours from the
time the ED physician orders the CT scan
until the final results are available, a savings of one-and-a-half hours that is attributable to the Definition. Similarly,
at the University of Pennsylvania, the
time from CT order to final report during
daytime hours averages about two-anda-half hours, but it is often closer to one
hour, Litt says. In a separate cost analysis,
Litt found that determining the cause of
chest pain in low-risk patients using a protocol of serial electrocardiograms, serial
cardiac enzymes, and nuclear stress testing cost $11,000 to $13,000 per patient
in the hospital and $6,500 in the chest
3
3
3 Pulmonary embolism (arrow).
pain unit. By comparison, the estimated
cost of using a DSCT-based protocol was
$3,000 to $3,500.
In addition to immediate cost savings, Dual
Source CT offers other economic benefits.
For example, up to three-quarters of lowrisk patients with chest pain can be dis-
“It is important to note that we have scanned
patients with heart rates of 90, 100 and
110 beats per minute on the Definition with
very positive results.”
Michael Gallagher, MD, Cardiologist, William Beaumont Hospital, Royal Oak, Michigan.
charged immediately after the CT scan,
avoiding the cost of further testing and
intervention. In addition, relieving the
beta-blocker bottleneck means that more
patients can be scanned in the CT suite
and more patients can be treated in the
ED in the course of a day. “Our ED is full
almost all of the time, so sending patients
home more quickly frees up resources for
other patients,” says Litt.
Scans for a Wider Range
of Patients
The Definition successfully images other
challenging cardiac patients as well –
for example, those with atrial fibrillation
and other irregular heart rhythms. Dual
Source CT has several advantages over
a 64-slice scanner in such patients. First,
scan times are so much shorter, it is less
likely that variations in heart rate will
Cover Story
4
4 Volume rendered image of a dual energy examination of the hands of an adult patient with
acute gout. With the dual energy information, deposits of uric acid can be detected within the
tophi. Areas of active inflammation additionally show an increased contrast enhancement.
occur during the scan. Second, because
the Definition does not rely on multisegment reconstruction, it produces highquality images even in patients with
irregular heart rhythms. And perhaps
most important, a temporal resolution of
83 milliseconds is fast enough to accommodate any heart rate. “We’ve certainly
found the dual source scanner to be very
useful in allowing us to freeze cardiac
motion, even with a variable heart rate,”
Litt says. Obese patients are no longer a
major challenge to image with the Definition. The ability to use a combined total
of 160 kW of power from two independent x-ray sources enables Dual Source
CT to overcome tissue attenuation in the
chest. In the past, cardiologists at William
Beaumont didn’t scan patients with a
body mass index (BMI) of 39 or greater –
think of a person 5 feet 11 inches tall and
weighing 280 pounds – because the im-
ages were typically too noisy. Today they
are considering relaxing that standard.
“With the Definition we get a better signalto-noise ratio in obese patients,” says
Gallagher. “In particular, we’ve noted improvements in those who have both a
high BMI and a high heart rate – patients
who were very difficult to image with the
64-slice scanner,“ says Litt. “We’re scanning pretty much anybody they throw at
us now, and getting good-quality studies
in almost everybody. The big difference is
that we’re much more confident in the diagnoses we make in obese patients.”
Increased diagnostic confidence translates into less radiation exposure to the
patient. In the Journal of the American
College of Cardiology study, William
Beaumont researchers found that approximately 11 % of studies performed on the
64-slice CT scanner were uninterpretable
as a result of motion artifact, respiratory
artifact, an inadequate signal-to-noise ratio as a result of obesity, and other technical factors. Because the Definition produces fewer nondiagnostic scans, fewer
patients require nuclear stress testing or
cardiac catheterization to determine the
physiologic significance of a questionable
finding.
And although using two x-ray sources
might suggest an increase in radiation
dose, Dual Source CT can substantially reduce patient exposure for cardiac applications. As the Definition images the heart
twice as fast, an adaptive ECG-controlled
pulsing can apply the dose necessary in
less than half the time. In addition, DSCT
adapts the table speed according to the
heart rate of the patient, thus automatically reducing cardiac dose at higher
heart rates. Besides, the resulting improvement in diagnostic confidence is likely to
reduce radiation exposure over the long
term. According to Litt, about 20 % of patients who come to the ED with chest
pain return to the hospital within a
month with the same symptoms. Because
emergency physicians have confidence
in the reliability of cardiac CT, they are
less likely to repeat the scan than they
might be with nuclear imaging.
“By doing CT, which gives a lot of confidence in a negative study, you’re avoiding
the need for further studies down the
road and perhaps decreasing the overall
radiation that that patient will be exposed
to in a lifetime,” Litt says.
Dual Energy Imaging Enables
new CT Applications
Everyone knew that cardiac imaging
would leap forward with Dual Source CT.
The surprise was how important dual
energy imaging would become. Once
considered by some to be an intriguing
bonus of Dual Source CT, dual energy
imaging is quickly becoming a workhorse
application in its own right.
The ability to simultaneously operate two
x-ray sources at different energy levels –
and therefore differentiate materials like
fat, soft tissue, and contrast agent on the
basis of their unique energy-dependent
attenuation profiles – is opening the door
to a host of clinically useful applications.
“We’re ramping up and doing more scans
with dual energy every day,” says
Johnny Vlahos, MD, an assistant professor of radiology at NYU Medical Center in
7
Cover Story
New York City. “I suspect we’ll soon be
doing the majority of our studies with
the dual energy technique.”
Since August 2006, Vlahos and his colleagues have scanned perhaps 120
patients using dual energy. One of the
most useful dual energy applications in
the chest and abdomen is the creation
of virtual noncontrast images. This is
accomplished by acquiring data at both
80 kV and 140 kV. Because iodine has its
maximum attenuation at low energy, the
80 kV dataset can be used to subtract
contrast material from the image, creating a virtual noncontrast image, and to
compare before and after images to
highlight areas of contrast enhancement.
This technique has many uses. For example, in an area of the liver that shows
increased density on contrast-enhanced
studies, differentiation of an abnormal
lesion from focal fatty sparing may be
difficult. Virtual noncontrast images
show the density of the liver before contrast administration, while virtual contrast images depict areas of iodine uptake. Both aid in diagnosis. The NYU
team routinely uses a similar technique
to assess hyperdense kidney cysts and to
differentiate benign and malignant nodules and masses in the liver and kidneys.
They are currently evaluating the use of
dual energy virtual non-contrast imaging
both to simplify CT follow-up of patients
who have had treatment for aortic dissection and to reduce radiation exposure. Instead of imaging before contrast
administration and during both arterial
and delayed phases of contrast enhancement, they are studying whether it is
sufficient to acquire only postcontrast
delayed-phase images using a dual
energy protocol, subsequently creating
virtual noncontrast images at the workstation.
“There is the potential to move from two
to three acquisitions in a single patient
to only one acquisition,” says Vlahos.
“The 80 kV images are very, very sensitive to iodine. We’ve had cases where a
contrast leak has been picked up only on
the delayed-phase 80 kV images.”
At the University Hospital of MunichGrosshadern, Christoph Becker, MD, routinely uses another dual energy technique: bone removal from CT angiographic studies. Dual energy techniques
have markedly simplified bone removal
5A
5B
5 With dual energy it
is possible to differentiate kidney stones
that require different
ways of therapy.
Calcium Oxalate
Stone (Blue) has to
be treated by intervention. Uric Acid
Stone (Red) has to be
treated with drug
therapy.
5B
on peripheral run-off studies, he says,
taking a laborious and time-consuming
manual chore and transforming it into
an easy step that takes less than a minute to perform.
“The results are amazingly good,” says
Becker, an Associate Professor of Radiology and Section Chief of body CT and
PET CT. “Dual energy really helps us to
create images of the entire vascular territory, from the diaphragm to the toe,
without any bony overlay. We are now
getting many more demands for this
particular application from our referring
physicians.” Similarly, dual energy techniques simplify bone removal from the
base of the skull, a critical step that enables clear display of the carotid arteries
during CT angiography.
In patients with suspected pulmonary
embolism, Vlahos has begun to routinely
perform dual energy imaging to evaluate
enhancement of the lung parenchyma.
This use of lung perfusion mapping in
combination with CT pulmonary angiography can assist in pinpointing pulmonary emboli and, perhaps, guiding therapy. “This technique goes beyond direct
visualization of the pulmonary artery. It
has the potential to improve our physiological understanding of pulmonary embolism,” he says.
Becker has found dual energy techniques
very useful for visualizing tendons and
ligaments, particularly in trauma patients, who will undergo CT scanning in
any case. He is also taking advantage
of dual energy findings to determine the
composition of kidney stones. Those
primarily composed of uric acid are best
treated conservatively with medication,
while other stones need more aggressive
management. Uric acid crystals can also
accumulate in the joints of patients with
Cover Story
6A
6B
6 Long distance peripheral
run-off examination
with dual energy technique. The ability to
show (Fig. 6A) or hide
(Fig. 6B) calcified plaque
(arrow) allows asessment of the remaining
lumen.
gout. Dual energy imaging is now providing new information on the source of
soft tissue swelling and the extent of
joint destruction in advanced gout.
Many other dual energy applications are
nearing clinical use. Plaque imaging is
perhaps the most intensely anticipated.
Increasingly sophisticated plaque removal tools can be used to mask calcification
and minimize blooming artifact, making
it much easier to evaluate the severity of
arterial stenosis. Perhaps even more intriguing is the possibility for dual energy
techniques to detect inflammation,
thereby distinguishing stable from unstable plaques.
“I’m pretty amazed at the progress in
dual energy techniques in just the last
year,” Becker says. “I believe dual energy
will become a substantial part of routine
scanning for a number of different applications we can’t even conceive of yet.”
“I’m pretty amazed at the progress in dual energy techniques in just the last year. I believe
dual energy will become a substantial part of
routine scanning for a number of different
applications we can’t even conceive of yet.”
Christoph Becker, MD, Associate Professor of Radiology and Section Chief of body CT and PET CT,
Department of Clinical Radiology, University Hospital of Munich, Munich-Grosshadern, Germany
Medical writer Catherine Carrington holds a
master’s degree in journalism from the University
of California Berkeley and is based in Vallejo, CA.
9
News
Professor Gerhard Mostbeck,
MD, Department of Radiology,
Otto Wagner Hospital and
Medical Center, Vienna, Austria.
News
Maximum CT Capabilities
in Minimum Space
In a discussion with SOMATOM Sessions, Professor Gerhard Mostbeck, MD,
Department of Radiology, Otto Wagner Hospital and Medical Center, Vienna,
Austria, describes how daily workflow has improved with their new SOMATOM
Emotion 16-slice configuration.
Interview by Robert Harsieber, PhD
Professor Mostbeck, you selected the
new SOMATOM® Emotion 16 for your
department. What were your criteria?
Image quality, of course, is always the
primary consideration. But an important
issue was also the small space requirement. At our location we have a lot of CT
activity, but very restricted space, so we
were pleased that we did not need a larger room for the new scanner. Another deciding factor was air-cooling. If we were
to convert to water-cooling, we would
have to run water pipes through these
old walls and then have to deal with the
waste water as well, involving a lot of extra costs. With its air-cooling, the Emotion saved us much expense. We were
also positively influenced by our previous
experience with the Emotion 6-slice configuration that proved to be extremely robust. Many different people operated it
and there were hardly ever any problems.
We also like the new practical storage box
for clinical accessories located close to
the patient.
To what extent has the new interface
influenced your operations?
Our radiology technicians now work with
pretty much the same interface that they
already know from magnetic resonance.
On the other hand, Siemens has added a
few things that significantly improve patient throughput. For example, there is a
menu list that gives the operator the option of saving a patient’s data alongside
the scan data, a very practical archiving
feature.
We also have night shifts that are staffed
to some extent by colleagues who come
from other clinical backgrounds. In these
cases, the “syngo® Expert-i” software is
important, because it allows a user on an
external computer to access the monitor
of the CT. The night operators use this
feature to quickly get external, expert
opinion when needed.
How important are workflow and
speed?
The elevation from a 6- to 16-slice configuration means a very great improvement
in image quality, of course, and, thanks
to the new applications, also in diagnostic workflow. This is something we have
now grown accustomed to, and we
would surely miss this efficiency if it were
no longer available for any reason.
For example, the biopsy mode and the CT
transillumination (CT fluoroscopy) are
substantial improvements. And the fact
that the scanner reconstructs very rapidly
is also an important feature.
One can process data and, on a second
workstation, inspect, analyze and reconstruct it at the same time. Our clinical
routine and throughput are greatly facilitated when we can take the 1,000 or
1,500 image datasets that we make during a routine examination of the thorax
and abdomen, and reconstruct them easily and quickly.
Which applications are particularly
important for you?
Except for heart examinations, which are
not within the capabilities of our hospital, we conduct a large volume and large
variety of computed tomography scans
here. Our emphasis is on the lungs, abdomen, neuropsychiatry, orthopedics and
similar areas.
Our pulmonary center – including thorax
surgery and two lung departments – is
one of our largest. These need special
software tools to analyze CT data. We do
many biopsy procedures in the chest and
pre-operative wire markings of small pulmonary nodules before they are removed
by thoracic surgeons using video assisted
thoracic surgery (VATS).
CT-guided biopsy or wire marking of
small pulmonary nodules less than 1 cm
in diameter is challenging. Respiratory
movements of the nodule make placement of a biopsy needle a demanding
task. Probing with a needle several times
for a pulmonary lesion increases the risk
of complications like pneumothorax or
bleeding. Thus, exact placement of the
needle tip in a single step is extremely
important.
This biopsy mode of the Emotion 16-slice
configuration supports us and shortens
examination times substantially. It also
helps us to reduce the number of X-rays,
compared to what we used to do.
We were able to determine this after our
first 40 or 50 biopsies. Furthermore,
there is a new function that helps us to
11
News
“With the SOMATOM Emotion 16 today’s resolution
achieves new dimensions. Today we actually see, for
example, things in the lungs that previously we could
not detect at all.”
Professor Gerhard Mostbeck, MD, Department of Radiology, Otto Wagner Hospital and Medical Center, Vienna, Austria
recognize the number and origin of nodules in the lungs. Radiologists are not
perfect – we make mistakes – but now
we have new computer aided detection
(CAD) software that automatically recognizes and marks suspicious structures for
us.
In what other ways has the SOMATOM
Emotion 16-slice configuration been
useful?
The Emotion provides high image quality
as well as software for special applications. For example, neuro-radiology plays
a key role in our work here. We support a
stroke unit that encounters, on average,
one stroke per day. So of course, it is important to be able to image the vessels of
the brain.
There is also a new solution with which
we can subtract the skull bones, and
then, from what is left on the scan,
graphically bring out and highlight the
vessels. That has worked very well in clinical routine, alongside an existing CT perfusion procedure that provides us with
hemodynamic information about ischemic brain areas.
A stroke is an illness that requires immediate clinical treatment, but does not
necessarily show up as a change in a routine CT.
With CT-perfusion, we can recognize
problems very early. While a conventional
CT is still negative, suspicions surface
that possible permanent damage is
occurring, so we can immediately begin
lysis therapy. This is quite significant and
practical.
Furthermore, the new Emotion 16 is very
effective for virtual representations. In radiology today, we try to replace demanding examinations with procedures that
are less stressful and invasive. A starting
point in the diagnostic framework is to
look for colon cancer via a virtual examination of the colon. Another one is to
make a “virtual flight” within the bronchial system. With this technology we can
offer simulations to our colleagues who
later perform the actual surgeries, and
they know in advance what they will find
when they get there.
Another impressive feature of the
SOMATOM Emotion 16-slice configuration is that we can select automatic
multi-planar reconstructions – coronal
and sagittal – from these data. This is,
in comparison to the predecessor model,
a substantial improvement.
One has a better spatial conception
through scrolling various planes. When
imaging lung cancer, there is definite
improvement in the ability to assess tumor infiltration of the lobar fissures or
the chest wall. And an additional capabil-
Axial thin section
CT and coronal
MIP: Multiple treein-bud configurations representing
small airway disease. Mycoplasma
pneumoniae was
diagnosed.
News
“Another novelty of the SOMATOM Emotion 16-slice configuration is that we can select
automatic multiplanar reconstructions – coronal and sagittal,” says Prof. Mostbeck.
ity that is important is that we can fuse
PET data from the Department of Nuclear
Medicine at the Wilhelminen Hospital
here in Vienna with our CT data. This cooperation has a crucial influence on oncology because we often prevent unnecessary operations, which certainly results
in better healthcare for the patients.
How has rapid technical progress
changed your clinical routine?
Tremendously. CT is one of the most innovative techniques now in existence. From
development of the conventional CT to
the single slice spiral CT to multi-detector
CT, we are constantly achieving better resolutions and shorter examination times.
CT will continue to get better and faster
until, one day, it will replace conventional
lung X-rays completely because the CT
scan, at some point, will take no longer
than two seconds. How-ever, this also creates a communications problem. It is no
longer a simple matter, when conferring
with our clinical colleagues, of hanging
up the images and saying, “There is your
tumor.” We have enormous datasets, so
we need solutions that allow these data
to be presented as simply and as three-dimensionally as possible, –offering a usable view of the pathology.
That is the essence of CT progress, to be
able to reduce the huge volume of data to
a simple illustration that I can view, comprehend and diagnose on a computer
monitor and then pass on. The applications that we already have available are
important in this regard and I am looking
forward with great expectations for
future developments. Through modern CT
technology, we have also learned that
radiologists are humans and therefore,
not 100% perfect. The expectation that
we spot every nodule is, in practice,
impossible.
As humans, we are incapable of filtering
crucial information from these huge data
sets that we acquire daily. We are inclined
to agree contentedly. Therefore, today’s
computer-aided diagnostic systems are
important. Diagnosis can be improved
substantially by the interaction of humans
and technology.
In this sense, technology is incorruptible.
And with the SOMATOM Emotion, not
only is the technology mature, but
Siemens also has seriously considered
how such questions can be answered.
From our point of view, this is the criteria
for a well-designed product.
What are your thoughts about cumulative radiation?
The history of low-dose CT covers only
the last seven or eight years. There is a rethinking going on in the radiological
world. One increasingly asks oneself, “Do
I need the best image quality for each
diagnosis?” I think not. I need image quality that permits me to make a diagnosis,
but not always the optimum, which, due
to physical laws, also is the one that
requires the highest dose. With older
patients in oncology, this is not such a
major concern. But with children, with
young women, and with chronically ill
people who must be examined again
and again, this is clearly important.
With low-dose CT solutions like CARE
Dose4DTM, the dose level can be fine
tuned to the lowest level possible for the
image quality required in the patients’
best interest.
On the other hand, today’s resolution
achieves important and useful new dimensions.
That’s true. Today we actually see, for example, things in the lungs that previously
we could not detect at all. With 10 –12
mm layers of resolution, a 3 mm nodule
went unnoticed; we simply did not see it.
Today the spatial resolution is increasingly
better, and this is a crucial help to our diagnoses. On the other hand, this creates
some additional challenges. The Americans have a name for it: “things you wish
you never had seen.” Not everything that
one sees is directly responsible for illness.
One must say to the patient, you have
three nodules, 3 to 5 mm in size, and
such nodules are with 95% certainty benign. You tell the patient not to worry, but
that he nevertheless must return in six
months for another examination to check
whether or not the nodules have grown.
Patients must learn to deal with this. The
process must also be computer assisted,
because, with the human eye alone,
such developments cannot be accurately
measured.
Robert Harsieber, PhD, is a freelance business
journalist, author, publisher and editor-in-chief of
Ärzte EXKLUSIV. He is based in Vienna, Austria.
13
News
Vahid Yaghmai, MD, Associate Professor of Radiology at Northwestern University-Feinberg School of Medicine, Illinois.
Let the Computer do it!
Fully Automated Tumor Tracking With
syngo CT Oncology
By David J. Tenenbaum
Before data becomes information, it must
be thoroughly examined and analyzed.
And as CT scanners produce a growing
torrent of data, radiologists confront a
data-or-information question every day:
how to obtain the maximum patient benefit from the hundreds of slices that an
advanced CT scanner produces from each
patient scan?
Rigorous, accurate and repeatable analysis
of CT scans is a matter of life and death
in oncology, but the sheer quantity of
data raises the potential for operator fatigue and even error. And these dangers
are multiplied by the regular follow-up
studies needed to track tumor response
to treatment.
But wading through data is precisely why
computers were invented. Several years
ago, Siemens CT software gained the
capability to automatically detect tumors.
And now the new syngo® CT Oncology
has the capability to automate lesion
measurement, and even brings volume
calculation into routine tumor evaluation.
Quick, Accurate and Consistent
In preliminary tests, Vahid Yaghmai, MD,
Associate Professor of Radiology at the
Northwestern University Feinberg School
of Medicine, Chicago, Illinois, says the
software matched the best human measurements. “In our experience, we have
seen an excellent correspondence between a manual measurement of lymph
node and most liver tumors, and the
automatic software measurement.
It’s very quick, accurate and consistent
in measuring lesions using the RECIST
(Response Evaluation Criteria in Solid
Tumors) and WHO (World Health Organization) standards.” Yaghmai is Medical
Director of CT at Northwestern Memorial
Hospital - Northwestern University, a tertiary care hospital in Chicago with one of
the largest oncology units in the United
States.
In May, he reported to the American
Roentgen Ray Society that manual and
automatic segmentation and measurement of abdominal and pelvic lymph
nodes corresponded closely, according to
both RECIST and WHO criteria. Similarly,
he reported to the Society of Gastrointestinal Radiologists that the software successfully segmented and measured 22
liver lesions on contrast-enhanced CT
scans from 12 patients.
Fast, accurate and repeatable tumor segmentation and measurement are significant advances, but syngo’s new ability to
automatically calculate tumor volume
could have equal importance. Studies
have already shown that the volume of
lung tumors may be valuable for assessing progression or regression; similar
studies for liver, bone and brain tumors
remain to be done. Although the role of
News
Greater accuracy may also help resolve
long-standing questions about the relative
value of RECIST and WHO standards.
There is a lot of debate, but a lot of that
stems from the issue of human error in
manual segmentations.
syngo CT Oncology also offers workflow
improvements. “In a large oncology center,
measuring lymph nodes in multiple dimensions and reporting on multiple lesions in
every study is a very time-consuming process,” Yaghmai says. “An automated way of
measuring lesions would really improve,
the workflow. You decide which lesions to
evaluate, and click on as many as you
want. Theoretically, somebody who is not
a radiologist can look at lesions on a follow-up study.”
Volume as a Standard Modality?
One click 3D-segementation and size evaluation of liver lesions with syngo CT Oncology.
volume in determining tumor status
remains subject to further research. “Intuitively, we think it should be important,”
says Yaghmai. “But until now, the difficulty of performing volume measurements
has limited our ability to validate this.“
Simplified Follow-Ups
To obtain automated measurements
from the syngo CT Oncology*, a radiologist clicks on the lesion on the display, and
immediately receives a readout of x, y,
and z dimensions, RECIST and WHO measurements, and lesion volume. If the
scan is a follow-up, the system displays
previous data on the same lesion, and
calculates any dimensional change during
the interim.
A simplified follow-up is one of the biggest
benefits of this new syngo software; there
is no need to “find” the same tumor on
previous images, and then determine
which slice shows the greatest single
dimension for RECIST or WHO measurements – those repetitive functions are now
all embedded in the software. “When you
follow patients based on these measurements, you want consistent and reliable
data, and this software gives reliable and
consistent information. It virtually eliminates human error and the variations in
measurement that can occur when doing
it manually,” says Yaghmai. “Despite advances in technology, consistency remains
a problem in radiology. There have been
many studies showing that measurements
of the same lesion by two observers will
be different. syngo CT Oncology eliminates
that part of the inconsistency.” This improvement may be particularly important
in irregular tumors, with poorly defined
margins that are difficult to measure.
Better Patient Care
On the practical level, automated measurement can improve the accuracy of comparisons when patients change hospitals.
“Many patients are first imaged at a small
community hospital, and we want to standardize the way we are following these tumors; it’s really about better patient care,”
says Yaghmai.
Automated measurement can also advance
the state-of-the-art in oncology, by improving the accuracy of tumor assessment during clinical trials, he adds. There is much
push from the National Cancer Institute to
standardize the way we follow up tumors.
There is a lot of variability in how different
centers do follow-up, and we want to standardize how we acquire images and measure these tumors.
In the longer term, automated tumor measurement can take radiology firmly into
the third dimension. While each component of a CT scan is a two-dimensional
slice of the patient’s anatomy, tumors
themselves are three-dimensional objects,
and the new-found ability to measure
volume will allow comparisons to see
whether volume, RECIST or WHO is most
appropriate for evaluating treatment.
Already, data regarding the volume of lung
cancer nodules “suggests that volume
should be the way to follow treatment,”
Yaghmai says. “However, nobody knows
what volume means in terms of patient
management for tumors of the liver or
lymph nodes. Even before the precise role
of volume measurements is determined,
accuracy and repeatability have value in
improving patient care,” says Yaghmai. “We
do not want the human factor to be a component of these measurements. It’s better
for patient to have realistic information.
Whether or not volume becomes a standard modality for evaluating treatment,”
Yaghmai says, “software like this will be
eventually standard for any follow-up of
oncology patients. Previously, the technology was not available, and now it is.”
*Pending 510(k): The information about this
David J. Tenenbaum, reports on science, health
and environment, and is co-author of Visualizing
Human Biology, published by John Wiley and
Sons (2007).
15
News
syngo Circulation - Siemens Scientifically
Validated Cardiac CT Software.
By Lars Hofmann, MD, Global Clinical Marketing Manager, Cardiac and Acute Care CT, Siemens Medical Solutions, Forchheim, Germany
Modern post-processing software tools
have gained increasing significance in
routine diagnosis over the past years. It
is of high importance to offer not only
a variety of software features, but at the
same time, to validate accuracy and functionality against existing gold standards.
Researchers at the University of Munich,
Departments of Clinical Radiology and
Cardiology, evaluated the accuracy of
syngo® Circulation as a quantitative coronary CTA analysis tool in reference to
quantitative coronary analysis in conventional angiography*. This makes syngo
Circulation the first coronary analysis
software to be scientifically validated.
The group of Busch et al. concluded that,
“the automatic segmentation of the
whole coronary artery tree has become
routinely feasible and has eased post-processing.” Additionally it is important to
note that, “the diagnostic accuracy of CTA
can be improved with this software,”
which “makes the software a very helpful
tool to improve diagnostic accuracy
with the quantitative grading of stenosis.”
syngo Circulation has reached its third
development stage in two years. Major
syngo Circulation Plaque Analysis.
improvements include the completion of
the functional and myocardial evaluation
as well as improved accuracy and flexibility
for quantitative coronary analysis. New
plug-ins allow the automatic detection of
pulmonary emboli** and the fusion of
cardiac CT data with SPECT and PET data.
syngo Circulation is the only cardiac CT
software that allows the complete cardiac
morphology and function evaluation in
one single software.
* The study of Busch et al. was pre-published as online
issue in European Radiology on December 16, 2006.
**Not commercially available in the US.
Flexibility for the Future – Now
One significant advantage of the SOMATOM Sensation Web Selection is its
combination of state-of-the-art 64-slice CT imaging capabilities with the
dedication to provide an exceptionally streamlined CT workflow. This makes
it the premium solution to fulfill todays high end CT expectations.
By Tim Friend
Radiology workflow at Alamance Regional
Medical Center (ARMC) in Burlington, N.C.,
has entered the jet stream. The vehicle
whisking this remarkable community hospital on a wickedly fast ride into the future
is SOMATOM® Sensation Web Selection.
According to ARMC’s RIS/PACS administrator Chris DeAngelo, this new ride is a
fully-loaded package with medical imaging technology and IT features few people
have seen before.
Siemens describes its SOMATOM Sensation
Web Selection as the world’s first Webenabled CT, providing “Zero Delay” Workflow Solution with instant accessibility
of 3D volume data to users at any location, 24 hours a day. Getting onboard
with SOMATOM Sensation Web Selection
marks the second time in two years that
ARMC has become first in the world to
obtain brand-new CT technology and
IT workflow solutions from Siemens. In
2005, ARMC was first to receive the
SOMATOM Sensation 40. Now the 238-
bed hospital has upgraded the 40-slice
machine to a SOMATOM Sensation 64
Web Selection – complete with new hardware and software, and protection against
obsolescence. But what DeAngelo says is
most noteworthy about the upgrade is
that it was done “without a forklift,” using
the existing SOMATOM Sensation 40.
The entire upgrade, which gives Almance
the ability to conduct full cardiac CT angiography with the fastest gantry available
on the market, was completed in a day
17
Business
“Now we can say we have a
whole brand-new CT scanner
with excellent image quality
and the sizzling gantry
speed of 0,33 s at minimal
investment.”
Chris DeAngelo, RIS/PACS administrator, Alamance Regional
Medical Center, Burlingtion, N.C.
and at a fraction of the cost of buying a
new 64-slice machine.
“When Web Selection came onto the
horizon, we immediately put it into our
crosshairs,” DeAngelo says. “We were able
to do the upgrade to Web Selection very
economically with minimal effort. It was
easy on the wallet and an easy install.
This made it possible to continue with our
initial investment while keeping up with
latest technology and with a minimal
amount of downtime. Now we can say
we have a whole brand-new CT scanner
with excellent image quality and the
sizzling gantry speed of 0.33 s at minimal
investment.”
It seems safe to say that ARMC Senior
Vice President Carol Hudson, as well as
the radiology department she oversees, is
enjoying life at the leading edge. “We are
very excited. The upgrade to the 64 gives
us the increased clinical functionality we
needed to move into full cardiac imaging,
which all of the big medical centers offer
now and whose technology the local
community is beginning to ask for,”
Hudson says. “But we’re particularly excited about how images can now be acquired. This is certainly going to improve
workflow and turnaround for patient
results and reporting. We are seeing immediate benefits.”
Cutting Edge in CT Imaging
and Workflow
Alamance is the first hospital in the US
to receive the SOMATOM Sensation WebSelection. DeAngelo is delighted to be the
first customer to use it. Alamance performs CT for all medical indications, but
it has had its eye on cardiac CT angiography. With the SOMATOM Sensation 40
scanner obtained in 2005, the hospital
began expanding into cardiovascular
imaging, primarily for peripheral arteries
and carotids. Now the hospital is planning
for cardiac CT angiography, expanding it
patient base as the place to be for diagnosing coronary artery disease.
SOMATOM Sensation Web Selection
addresses exactly these needs, with its
advanced imaging capabilities. It offers
industry’s highest rotation speed of
0.33 s which is essential to freeze the cardiac motion. At the same time the highest isotropic resolution of 0.33 mm enabled by Siemens unique z-Sharp
technology gives the user the ability to
see smallest detail such as the entire coronary artery tree or even coronary instent lumen.
The combination of both, speed and
resolution is key in cardiac imaging. Not
only to freeze motion and make smallest
details clearly visual for the physicians but
especially to image calcified plaques with
as little blooming artifacts as possible.
Combined with the latest evaluation software, the SOMATOM Sensation is a powerful tool in Cardiac CT.
What´s more. DeAngelo says the
SOMATOM Sensation Web Selection’s
Multimodality workplace is set up with
sophisticated post-processing software
for a wide variety of functions.
“We have a new Multimodality Workplace
with advanced post-processing capabili-
ties such as syngo® Circulation software
that enables cardiologists to analyze
coronary blood vessels in a very high tech
but easy manner. After the CT scan is acquired, the radiologists can do post-processing, analyze their data to generate
special cardiac images, and make screen
shots or reports. As techs, we will look at
the images, isolate blood vessels, calculate the percentage of stenosis, and send
those images to PACS,“ says DeAngelo.
Besides its superb imaging capabilities,
the SOMATOM Sensation Web Selection
is designed to deliver a streamlined CT
workflow with Zero-Delay from the very
beginning of patient preparation to the final diagnosis. It starts with a “smart” feature, CARE Contrast, that allows the technologist to initiate the CT Scan right at
the injector in the scan room at one click
of a button without having to leave the
room. This saves time and increases patient care. It continues with a minimal
processing time of images realized by
an option called Workstream4D, enabling
the direct reconstructions of multiplanar
images. A feature, that helps busy departments to get valuable additional information in less time. Even beyond the CT
Department the Web Selection offers
tools to provide a so called “Zero-Delay”
CT workflow. To enable physicians to call
for a second opinion or to have a CT Tech
call for advice for reconstruction of images, syngo Expert-i is the perfect tool to establish a connection between the workstation and any remote PC instead of
having the expert physically come to the
workplace.
Order
Plan & Prepare
Patient Preparation
Scan & Reconstruct
Process
Read & Report
Distribute
Scan Data
MultiModality Workplaces +
CT Clinical Engines +
syngo Expert-i
syngo Expert-i (Remote)
syngo WebSpace (Clients)
Office PC
Acquisition
Workplace
CT
Workplace
WebSpace
Server
Home
PC/Laptop
Shared Database
Fast Data Link
PACS
Archive
PACS Reading
Workstations
With syngo WebSpace 3D data are available anytime and anywhere.*
Remote Technology Brings
Images Closer
Any outside observer at Alamance’s
radiology department can see that all is
in motion – fluid, linear, traveling at the
speed of light – from the moment a CT
technician pushes the button on the
64-slice scanner, to the automatic postprocessing of 3D volume data in a dedicated two-terabyte server, to a physician’s
click of a mouse only moments later to
access the images from any remote location with an Internet connection.
According to Hudson, the time patients
spend waiting to be scanned and to receive a diagnosis is diminishing. The time
technicians previously spent download-
ing images from a PACS archive for postprocessing at the Multimodality workplace
can now be used in more productive
ways. Radiologists and surgeons no longer have to wait in line for the Multimodality workplace to view the highest
quality CT images, nor must they waste
time and effort switching between the
workstation and a personal computer
when viewing images in 3D. And that
midnight drive from the radiologist’s home
to the hospital simply to spend ten minutes reading an image? That’s history, too.
“We will see significant costs savings in
the long term, but the benefits are immediate. Physicians are able now to access
images over the Internet, which is saving
everyone time and money,” Hudson says.
“From the administrative perspective,
Web Selection gives us the ability to
continue to be out there on the innovative and up-to-date use of technology,
not only for the patient, but for the staff
and their work time and input. This gives
us efficiency in both arenas. We are fairly
sophisticated with technology already,
but this takes us up another notch in the
technological world.”
The SOMATOM Sensation Web Selection,
which was introduced by Siemens at
RSNA 2006 contains a number of vital
components. Perhaps the most glamorous one beside the excellent image quality
is a technology called syngo WebSpace.
DeAngelo says WebSpace has made it
possible to transform any personal com-
* Internet connection required.
19
Business
SOMATOM Sensation Web Selection.
puter or laptop into a “thin-client” clinical
workstation with high-end CT imaging
and post-processing capabilities similar to
the Multimodality workplace. Rather than
having to sit down at a dedicated workstation to access 3D volume data, users
gain access from any location over the
Internet using a standard broadband connection. Making life even simpler, DeAngelo notes, the system uses the same familiar syngo platform as all Siemens
imaging systems. This makes WebSpace
easy to learn, because the language is the
same and the computer screens are familiar in appearance. Training is a matter
of learning a few extra keystrokes, he
says.
“Like InSpace on Steroids”
As a former CT technician and now
Alamance’s RIS/PACS guru, DeAngelo is
most excited about what most people
never see – Web Selection’s hardware
server infrastructure and the new imaging software. The state of the art for
image processing has been InSpace,
which operates with the Multimodality
workplace. InSpace, which became available in 2003, changed the landscape
from 2D axial images to 3D volume
images. In the 19th issue of Siemens’
SOMATOM Sessions magazine, Elliot
Fishman said, “WebSpace is sort of like
InSpace on steroids. Everything we
could do on that workstation with
InSpace – on the Multimodality workplace
– at a fixed location we can now do
anywhere, anytime.* What that means
in practical terms is that WebSpace is
making 3D data practical for the common
man.”
Hudson says SOMATOM Sensation Web
Selection is transforming the radiology
department. While syngo WebSpace
resolves a key bottleneck in radiology,
namely limited access to Multimodality
workplaces, the SOMATOM Sensation
WebSpace server has resolved issues with
the massive amount of 3D volume data
and heavy computing power needed
for post-processing and image storage.
* Internet connection required.
Business
“We will see significant costs savings in the
long term, but the benefits are immediate.
Physicians are able now to access images
over the Internet, which is saving everyone
time and money.”
Carol Hudson, Senior Vice President of the Alamance
Regional Medical Center, Burlington, N.C.
Radiologists at Alamance recognized
early on the value of 3D imaging for many
medical indications compared to standard
axial images. The dedicated two-terabyte
WebSpace server that DeAngelo oversees
receives information instantaneously
via a Fast Data Link from the SOMATOM
Sensation. New software instantly does
the post-processing and makes it available
to users via the server’s Web connection.
Typically, technicians must download the
raw CT volume data onto a workstation
from an archival server and do post-processing, which takes time and “chews up
an enormous amount on space on my
PACS archive,” DeAngelo says. “With the
WebSpace server, we have an additional
two terabytes worth of space. For me, this
will keep the cost of maintaining the main
PACS archive down by not overloading it
with data. We can store our most current
images on the new server and keep our
overall costs low.”
syngo WebSpace can accommodate five,
ten or twenty simultaneous users, depending on an institution’s needs. Alamance’s package provides access for 10
users at any given time. As Alamance
becomes a local leader in cardiac CT
angiography with its 64-slice scanning
capability, DeAngelo sees this as a premium value for cardiologists and heart
surgeons. DeAngelo says physicians and
surgeons will be able to access 3D images
of a patient’s coronary arteries from their
personal computers. The images are available almost instantly after they are taken
in the radiology suite. Likewise, in those
facilities that provide cardiac surgery the
cardiac surgeons can view the images on
a computer screen in the OR while they
operate. DeAngelo says WebSpace also is
becoming popular with the hospital’s
orthopedic surgeons, who rely on 3D
volume data as much as cardiologists. But
new applications for WebSpace are essentially limitless. Hudson adds that having
access to 3D images over the Web makes
the hospital more attractive to patients
and to new referring physicians. A patient
and physician can view images together
on the physician’s computer when discussing a diagnosis and treatment options.
Investing in Flexibility
in the Future
“We were already a filmless radiology
department and fairly state of the art. But
with SOMATOM Sensation Web Selection
we see multiple advantages for us,”
DeAngelo says. “There is a huge workflow
benefit for everyone, including our radiologists and referring physicians – particularly orthopedic and vascular surgeons.”
“ARMC’s continued trust and investment
into the SOMATOM Sensation product line
shows the success of the technological
and clinical capabilities of the system.
Alamance’s decision to optimize its busy
CT program with the SOMATOM Sensation
Web Selection will accelerate the way they
can deliver patient care. The ability to scan
and post-process patients faster will have
a positive impact on patient throughput,
especially at peak times or with unexpect-
ed ER admissions,” says Jan Chudzik, Product Marketing Manager for the SOMATOM
Sensation. “The thin client-based accessibility of 3D images to the physicians anywhere and anytime will help to shorten
the overall process of patient diagnosis by
cutting out the typical delays of a workstation/PACS-bounded workflow.”
For any institution purchasing expensive
imaging equipment, flexibility for the
future is an important consideration, adds
Hudson. The rapid pace of technological
evolution can cause million-dollar imaging
systems to become outdated in just three
to five years. Purchasing the Sensation 40
with knowledge that it could be upgraded
to a 64-slice system gave Alamance the
flexibility it needed. Siemens’ e-Tune is
packaged with Web Selection to offer protection against technological obsolescence. e-Tune guarantees that Alamance
receives software and even hardware updates for the next several years.
DeAngelo is confident that the hospital
made the right choice, saying, “This will
carry us quite some time into the future.
The Web Selection with e-Tune extends
our original investment in 2005 in the
Sensation 40 to a total of five years.”
Tim Friend, a USA Today reporter for 17 years,
is now a freelance science and medical writer
based in Alexandria, Virginia. He is the author of
Animal Talk: Breaking the Codes of Animal Language, and The Third Domain: The Untold Story
of the Archaea and the Future of Biotechnology.
21
Business
Karl Engelhard, MD, Chief of the Department of Radiology
at the Martha-Maria Hospital in Nuremberg, Germany.
Although the Martha-Maria Hospital is a confessional clinic with
only 330 beds, it is able to compete with much larger hospitals.
Big Progress for a Small Clinic
Elevating to a new SOMATOM Sensation scanner has paid off
for a hospital in southern Germany, delivering more patients, more
revenues and better, faster diagnoses.
By Frank A. Miltner
“In CT diagnostics, we are clearly a step
ahead,” says Karl Engelhard, MD, Chief of
Radiology at the Martha-Maria Hospital
in Nuremberg, Germany. Since the beginning of 2007, this small, confessional
clinic of only 330 beds has been able to
compete with much larger hospitals. And
competition is fierce: about a dozen other
small hospitals, a university clinic, and an
urban hospital with 2,000 beds are available to patients in the Nuremberg metropolitan area, with its some two million inhabitants. “This significant progress for a
small hospital was made possible by up-
grading their existing Siemens single slice
CT to a new multislice, spiral, computed
tomography scanner, the SOMATOM®
Sensation 40-slice configuration from Siemens Medical Solutions.”
Word traveled fast about the acquisition
of the 40-slice CT. Just three months
after installation of this high-end system,
the number of CT scans had risen nearly
20 % to the present level of about 1,600
per year. Primarily private patients come
to the small hospital, some from as far as
100 kilometers away, for complex pre-clinical diagnoses. “We won’t have firm statis-
tics on this for another few months,”
notes Engelhard, “but the trend in numbers of scans is clearly rising.” Also helping the trend climb is the small radiology
team’s new ability to continuously further
extend its diagnostic spectrum.
Money (Also) Talks
Healthcare, of course, is the primary consideration but no clinic today can afford
to ignore financial matters.
“Siemens helped to make our move to
multislice CT happen through their
Business
The diagnosed ureteral tumor stands out (arrow) as do the contrasting white areas in the kidney and the ureter. “Only this
morning we discovered a ureter tumor that we would not have recognized with our old equipment,” Engelhard says.
attractive offering including the buy-back
of our old scanner.“ And the investment
of several hundred thousand euros – obviously still a significant sum for a small
hospital, amortizes itself at various levels.
There are already cooperative agreements with established physicians who
now send their patients to Martha-Maria
instead of to the large urban hospital in
Nuremberg or to the University Clinic at
Nuremberg-Erlangen.
And of course the diagnostic spectrum
has been greatly extended, compared to
that of the previous scanner, an eightyear-old, single slice, spiral CT. In MarthaMaria Hospital, the main benefactors of the
new scanner are oncology, gastroenterology, urology, orthopedics and cardiology.
All benefit from temporally and spatially
highly-resolved oncological and cardiological diagnostics, for example, and with
virtual colonoscopy and three-dimensional
representations of arthritic changes. The
new equipment brings additional revenues
as well as better conditions for patients.
Radiation exposure is clearly reduced,
and the time a patient must spend in the
scanner is a fraction of what it used to be.
This eases discomfort for the many patients who come for scans with breathing
difficulties and other problems. For
example, where the old single slice
system needed five or six minutes for a
chest cage CT, the new one needs only
15 seconds – and it delivers markedly
better results.
True to the Mission of its
Benefactor
Not surprisingly, this cuts costs. The new
CT does not require additional personnel.
On the contrary – the four physicians and
seven technicians in the radiology department now have more time for other
diagnostic procedures and for their patients. For the Martha-Maria Hospital,
this brings an ethical bonus: its benefactor
is the Protestant Mission Martha-Maria,
which operates on the principal of brotherly love and puts people at the center
of its clinical work. The chief of radiology’s
delight in his new clinical capability is
clearly noticeable.
“Thanks to multi-planar reconstruction
with thin collimation and temporally
highly-resolved contrast dynamics,” he
says. “Only this morning, we discovered
a ureter tumor that we would not have
recognized with our old equipment.”
Early discovery gives the patient a critical
advantage, because this sort of tumor is
aggressive and spreads easily. The
SOMATOM Sensation 40’s industry‘s highest spatial resolution, its fast, accurate
localization allows a rapid, low-risk surgical plan to remove it.
Political reform of the healthcare system
has, in the past few years, intensified
competition among German hospitals.
While some hospitals respond by cutting
back on services, Martha-Maria is trying
another approach: it is positioning itself
as a specialist where quality comes first –
and the SOMATOM Sensation 40 plays a
central role. “The marketing effect of this
scanner generates a positive influence on
the economics of the entire hospital,”
contends Engelhard. The improved preclinical diagnostics even bring in extra
patients on their own initiative.
23
Business
Custom-Made Advantages
“The choice of a Siemens CT also turned
out to be a great advantage when it came
to installation,“ says Engelhard. In this instance, Martha-Maria had some very exacting, demanding requirements. Planning was to begin only in late summer
2006, yet installation and full functionality had to be completed by December 31 –
because on the next day, January 1st,
2007, Germany’s value-added tax would
increase from 16 % to 19 %. This was a
literal case of “time is money.”
So Siemens Medical Solutions installed
the new equipment during the week between Christmas and New Year, a time
when little business is conducted and
when most other service companies are
on holiday. “The hospital administration
could not afford to have long down times
in CT diagnostics,” notes Engelhard.
Moreover, Siemens purchased the old
equipment and user training was com-
pleted within a few days. “One must
strongly emphasize: as a small hospital
with limited resources, we were very glad
that Siemens could offer us such a custom-made solution.”
Frank A. Miltner is a Munich-based media consultant and a scientific and medical journalist. He
is a former editor of the German magazine Focus
and editor-in-chief for Lifescience.de and Netdoktor.de as well as the author of several books.
A Workhorse as well for Cardiology
Interview with Falk Karsten Pohle, MD, Chief of Cardiology, Martha-Maria Hospital, Nuremberg, Germany
Dr. Pohle, you strongly supported the purchase of the
SOMATOM Sensation 40-slice configuration. Why this particular scanner?
I have worked for many years with Siemens CTs, and I know
very well that I can rely on them and their high image quality in
addressing cardiological questions. This CT is a true workhorse.
Of course, it is obvious that this 40-slice CT, compared to our
old single slice system, represents a quantum transition for our
non-invasive heart diagnostics, not only for our patients and for
our small hospital, but also for the whole region. Among nonuniversity clinics, at present we have no competition.
What has changed for the patients?
We can, for example, rule out coronary diseases, conduct
artery hardening analyses, recognize soft plaques, and diagnose
patients with small and middle pre-test probability or middle
PROCAM risk to the extent that preventive measures can then be
introduced. With this CT, we not only work more accurately,
but also spare many patients the discomfort of a heart-catheter
examination.
What has changed for your cardiology department?
Our reputation has grown noticeably, patient numbers have increased, and we now have a cooperative program with established cardiologists. Word spread about our cardio CT, and patients have begun to ask about it. This CT not only improves the
quality and thus the reputation of our Department of Cardiology,
it also provides for significant hospital revenues. It has been
only three months since we introduced the new equipment,
and we are fully on budget with our financial plans. The investment was worthwhile for us in all respects.
Falk Karsten Pohle, MD: “With this CT,
we not only work more accurately, but also
spare many patients the discomfort of a
heart-catheter examination.“
Business
Cardiac CT Takes Off
Detecting coronary artery disease in its asymptomatic stage is one
of the greatest challenges a cardiologist faces. The flight surgeons of the
German Air Force have had tremendous success in this area, as they
have developed a method using computed tomography for early diagnosis
of the disease in pilots. This unique method has gained increasing
recognition in aeromedicine worldwide.
By Sonja Fischer, Siemens Medical Solutions, Erlangen, Germany
Just as the captain of the Boeing 757 has
safely taken off, he feels a sharp pain in
his chest. He is panting for air. In his field
of vision, the controls blur with the decreasing landscape below, and before he
has a chance to set up radio communica-
tion with the control tower operators,
he collapses and is not able to continue
navigating the aircraft. What sounds like
a real horror-scenario actually took place
in February of this year in a Continental
Airlines aircraft. Fortunately, the copilot
was able to safely land the aircraft and
none of the passengers was harmed. The
captain, however, died from the consequences of his heart attack. Coronary artery disease (CAD) is still the most frequent cause of death in the industrialized
25
this reason, diagnosing CAD at an early,
asymptomatic stage is important for us as
flight surgeons so that we can prevent
any acute coronary syndrome that could
have immediate consequences for the pilot
and aircraft.”
Extraordinary Exposure
for Jet Pilots
Thanks to its high sensivity and specificity, DSCT has become increasingly recognized
in international aviation medicine when diagnosing CAD in asymptomatic pilots at the
German Heart Center, Munich, Germany.
“In terms of accelerated
temporal resolution,
SOMATOM Definition sets
groundbreaking standards.”
Stefan Martinoff, MD,
Director, Institute for Radiology and Nuclear Medicine,
German Heart Center, Munich, Germany
world, and can cause what in aviation is
feared as ‘sudden incapacitation in flight’.
Now, a specialized strategy should prevent
these events in both military and civil
aviation. This is what Christoph Wonhas,
MD, an internal specialist and cardiologist
at the German Air Force Institute of
Aviation Medicine in Fürstenfeldbruck,
Germany, sees as his most important
task. “The prevention of fatal occurrences
or sudden incapacitation is critical to
ensuring flight safety,” he stresses. “For
For jet pilots, a “sudden incapacitation
in flight” can be particularly dangerous.
They often fly alone and, in case of a
heart attack, there would be no one to
safely land the aircraft. In addition, specific conditions in the cockpit further
cause physical stress: extreme heat,
hypoxia, and high accelerating forces
that push blood from the head into the
legs and can shift internal organs up to
15 centimeters. These conditions increase
the danger of an acute coronary event
in persons with arteriosclerosis.
However, within the clinical aeromedicine
department in Fürstenfeldbruck, Wonhas
is responsible for more than just the
aeromedical assessment of military pilots.
As Assistant Director of the German Air
Force’s ‘Aeromedical Center,’ which has
been accredited for civil aviation, he also
assesses pilots from major German airlines on behalf of the German Federal
Office for Civil Aeronautics. He is currently
stationed at the US Air Force School of
Aerospace Medicine in Texas, taking part
in continuing aeromedical education.
There, the significance of CAD for aeromedicine has been confirmed for Wonhas.
Statistics from the Federal Aviation Administration (FAA), the civil aviation authority
in the US, indicate that pilot autopsies
have shown a higher-than-average percentage of coronary heart disease. From
1980 to 1982, the agency examined 710
deceased pilots. Of those, 3 % showed severe, and 66 % showed minimal to moderate coronary heart disease. Only 31 %
had no indications of arteriosclerosis of
the coronary arteries. “In Germany, we do
not have such large sets of statistics, because fewer people are actively flying.
Therefore, there are far fewer fatalities,”
says Wonhas. “However, forensic doctors
at the German Air Force Institute of Aviation Medicine have observed a similar situation, and several autopsies have found
more or less severe CAD or stenosis.” As a
result, the flight surgeons began to
search for a reliable method of detecting
Business
the disease early to help prevent sudden
inflight incapacitation.
Cardiac Health:
Strict Guidelines for Pilots
In aeromedicine, bicycle ergometrics is
recognized as the essential stress test
for the health and fitness of pilots. With
respect to CAD, however, ergometrics do
not enable diagnosis until a stage that
shows changes in the electrocardiogram
(ECG) due to ischemia. Yet before the coronary blood flow becomes insufficient,
the stenosis diameter has to reach 50 %.
This means that ergometrics are of significant value for assessing patients at risk.
However, during routine screening of
young, asymptomatic patients with a low
coronary risk score like Framingham and
PROCAM Score, as is the case of most pilots, this method has a coronary heart
disease hit rate of only 21 %. In addition,
the European JAR-FCL3 guidelines (Joint
Aviation Requirements for Flight Crew Licensing) can disqualify pilots with a lumen occlusion of 30 %. As such, for aviation it is very important to be able to
determine CAD in asymptomatic subjects
without high-degree stenosis. Until now,
invasive coronary angiography has been
the gold standard. However, physicians
do not want to subject asymptomatic patients to the risks associated with this examination every time there is a new, but
insignificant conspicuity in a stress ECG.
“Furthermore, we have found myocardial
scintigraphy, which is used regularly in
American aeromedicine, to be unsuitable
for detecting CAD in our pilots because it
does not enable display of the coronary
arteries,” says Wonhas. “However, with
multislice computed tomography (MSCT),
we found a fast, secure, and cost-effective
method for displaying the coronary arteries of asymptomatic pilots in suspicious
cases without having to risk an invasive
catheter examination. This was a method
we wanted to use,” he remembers.
Effective Cooperation
in Cardiac CT
For this reason, the German Air Force
Institute of Aviation Medicine looked for
a suitable cooperation partner in diagnostic cardiology and high-resolution cardiac CT, and found that partner in the
German Heart Center in Munich (DHM).
The DHM is one of the leading cardiac
centers in Europe, and was one of the
first facilities to use MSCT technology on
the heart. The center has been equipped
with state-of-the-art CT scanners from
Siemens since 2002. The first MSCT system that the center used was SOMATOM®
German Air Force Institute
of Aviation Medicine
The German Air Force Institute of Aviation Medicine in Fürstenfeldbruck is the central aeromedical facility for the German
Army, Air Force, and Navy. Its job encompasses the selection,
examination, and aerophysiological instruction of aircraft crews
for the German Armed Forces. It is also responsible for investigating aviation accidents, ergonomics, aerophysiology, and
dealing scientifically with aeromedical problems. The primary
tasks are performed in the following six departments:
Research, Science and Education, Air and Space Medicine
Clinical Aeromedicine
■ Forensic Medicine and Aviation Accident Medicine
■ Flight Psychology
■ Ergonomics
■ Aerophysiology
■
■
The Clinical Aeromedicine Department, where MSCT diagnostics
are used as a noninvasive cardiac examination procedure under
the direction of Christoph Wonhas, MD, is the largest depart-
ment. It is an interdisciplinary, polyclinical diagnostic center
with eight specialist groups: Internal Medicine, Orthopedics,
Neurology and Psychiatry, Ophthalmology, Ear-Nose-Throat,
Dentistry, Diagnostic Radiology, and Central Lab. Their task is to
examine and assess the medical suitability of all candidates for
military flight service. This includes follow-up examinations on
approximately 3,300 army, navy, and air force pilots and weapon systems officers for deployment on military aircraft. The institute uses equipment of the highest standard. Since 2003, the
German Air Force Institute of Aviation Medicine has also served
as the Aeromedical Center (AMC) for civil aviation on the order
of the German Federal Office for Civil Aeronautics. As a result,
frequent fliers such as Lufthansa captains, hobby pilots, and
flight attendants now round off the patient spectrum.
Source: German Air Force
27
Business
“MSCT is a fast, secure, and costeffective method for displaying the
coronary arteries of asymptomatic
pilots in suspicious cases, without
having to risk an invasive catheter
examination.”
Christoph Wonhas, MD, Internist and Cardiologist,
Air Force Institute of Aviation Medicine, Fürstenfeldbruck, Germany
Sensation 16, which was later upgraded
to a 64-slice system. This was then replaced by the latest high-end CT system
from Siemens in the summer of 2006:
SOMATOM Definition.
Stefan Martinoff, MD, Director of the
Institute for Radiology and Nuclear Medicine at DHM, and Jörg Hausleiter, MD,
cardiologist at the Department of Cardiovascular Diseases, both helped to develop
this innovative method for using MSCT in
aeromedical assessments. Martinoff is
impressed by the new SOMATOM Definition. “With this system, we took the opportunity to accelerate cardiac imaging in
terms of temporal resolution. In this area,
the new Dual Source CT sets a groundbreaking standard. The system is much
easier on the patient, and it is easier for
us to perform significant, high quality
coronary CT examinations,” states the radiologist. “In addition to the resolution,
which at 82 milliseconds is twice as fast,
there is a whole range of hightech features that make the Definition an excellent system for vascular and cardiac examinations.” For Wonhas, computed
tomography angiography (CTA) using
SOMATOM Definition is the method of
choice for aeromedical assessments: “The
primary advantage is the high negative
predictive value of almost 100 %. With
respect to flight safety, we can now rule
out whether an asymptomatic pilot is suffering from coronary heart disease with
greater certainty.”
From a cardiological perspective, Hausleiter particularly stresses the advantages
of CTA as a noninvasive method to identify
plaque-accumulation in the coronary
arteries. “Due to the high spatial and temporal resolution of CTA imaging, we can
show calcified as well as noncalcified
plaque.” During plaque rupture, blood clots
occur which can consequently cause a
heart attack. Therefore, Hausleiter assumes that these deposits – especially the
noncalcified – will, in the future, be increasingly considered for the diagnosis of
arteriosclerosis in asymptomatic patients
with low to intermediate risk to suffer
from CAD like the pilots.
Reliable Diagnosis
in Asymptomatic Pilots
Since 2003, Wonhas and his colleagues
have been using MSCT in aeromedical
assessments with the support of DHM. As
in the past, they routinely perform ergometrics at the Institute of Aviation Medicine once annually as a screening method.
Now, however, if changes are noted in
the ECGs and ergometrics when compared
to those from the previous year – for example, a new, higher-grade arrhythmia or
new ST segment changes – the physicians authorize additional, noninvasive
examinations. This means that a transthoracal echocardiogram (TTE) is performed
after ergometrics to rule out structural
heart diseases such as cardiomyopathy or
cardiac valve disease. On the same day,
the colleagues at DHM perform the MSCT
examination on the affected pilot. This
procedure has proven to be extremely effective. From 2003 to 2004, exactly 3,409
flight crew members were examined and
retrospectively evaluated in a study. In
1.73 % of cases (59 pilots), results proved
to be suspicious and required further examination. “Fortunately, we were able to
rule out coronary heart disease in 85 % of
them. However, we did find coronary artery disease in nine persons, with stenoses up to 90 %, and these were all asymptomatic pilots with a PROCAM Score of
about only 5 %,” says Wonhas. This perspective of the physician comes from 20
years clinical experience as an internal
specialist in an intensive care unit. In
2003, during his flight certification (flight
surgeons in the German Air Force are required to fly on a case-by-case basis),
Wonhas, too, had suspicious ergometrics
while being asymptomatic. CTA was performed, and the findings were normal.
“Therefore, I have a different perspective.
I understand the problem as an invasive
cardiologist, but also as a patient,” says
Wonhas. Martinoff of DHM can confirm
that Wonhas makes sensible patient selections for the examination based on his
experience: “Given the hundreds of pilots
in the German Air Force, the small num-
Business
2
1A
1B
1C
1D
1 If irregularities occur in the resulting electrocardiogram (Fig. 1A),
CTA is performed on the same day at the German Heart Center
(Figs. 1B - 1E). Exemplary findings (above) from Wohnas‘ CTA test
in 2003 which ruled out CAD for him.
ber that Wonhas sent to us to be examined in 2003 and 2004 had a relatively
high hit rate. The subsequent procedure
confirmed that the approach we are using makes sense.“
International Recognition in
Aeromedicine
Based on the results presented by Wonhas
and colleagues, the German Armed Forces
have since recognized CTA with MSCT as
the diagnostic procedure for their flying
service, and use it as routine. The Federal
Office for Civil Aeronautics, the highest
monitoring agency for aviation in Germany, has also accepted this method because of its high negative predictive value.
Internationally, NATO (North Atlantic
1E
2 Routine investigation at the Institute of Aviation
Medicine includes bicycleergometrie as indispensable
stress test.
Treaty Organization) has begun working
with MSCT to diagnose CAD. Wonhas is
convinced of the value of MSCT in aeromedical assessments, and hopes it will be
quickly implemented in aviation internationally to prevent harm. “To date, in
85 % of asymptomatic patients with a
newly occurring higher-grade ventricular
arrhythmia or non-conclusive new ST depression, our examination has clearly
demonstrated that their hearts are
healthy. On the other hand, in 15 % of
cases, we discovered coronary artery
disease at an early stage. All of these patients were able to receive special approval to fly once they began treatment.
For the pilot, this means minimizing the
risk of a heart attack before it happens.
He can be there for his family, and the
Armed Forces or civilian airline will continue to benefit from his expertise. As a result, our method makes a lot of sense.”
29
Clinical Outcomes Cardiovascular
Case 1
Heterotopic Heart Transplant With
Arrhythmic Heart Rate of 45 –125 bpm1,2
and Post-Surgical Control with Cardiac CT
By Shu-Hsun Chu, MD, Cardiovascular Center, Far Eastern Memorial Hospital, Taipei, Taiwan
HISTORY
A 52-year-old man suffered for two years
from dyspnea on exertion and chest
tightness. Because progressive symptoms
failed to respond to medical treatment,
the patient was admitted for heart transplantation evaluation. In April 2001, a
48-year-old head injury donor with good
cardiac function passed the brain-death
examination. During transport of the donor to the Far Eastern Memorial Hospital,
cardiac arrest occurred. Cardiopulmonary
resuscitation was performed immediately
in the ambulance. When the donor arrived at the hospital, his blood pressure
was 60/30 mm Hg, and heart rate 36 bpm.
An immediate sternotomy revealed that
the heart was already arrested, distended
and cyanotic. The donor was soon put on
1
1 VRT display shows
the heterotopic
transplanted heart
on the patient’s
right side and the
native heart on
the left.
Cardiovascular Clinical Outcomes
2
2 ECG trace shows
patient’s very high and
irregular heart rate of
45–125bpm. Despite
the unfavourable heart
rate, both hearts and
coronary arteries could
be displayed free of
motion.
cardio-pulmonary bypass (CPB). After
that, the heart started to beat again and
could maintain a stable hemodynamic
status even when CPB was weaned off.
Since the suitability of the resuscitated
heart as orthotopic heart transplant was
unclear, the hospital decided to do a heterotopic heart transplantation. Five years
after successful surgery the patient is in
good condition.
COMMENTS AND DIAGNOSIS
Using the SOMATOM® Definition for a recent follow-up exam, it could be clearly
determined that both hearts were functional, but with different heart rates and
rhythms. SOMATOM Definition’s high
temporal resolution of 83 msec in combination with reliable ECG-editing functionality was of crucial importance in obtaining diagnostic images of the rapidly
changing heart rates between 45 and
125 bpm.
3
3 Maximum Intensity
Projection (MIP) image
shows the artifacts
free coronary arteries
of the native heart
(arrow heads) and the
right coronary artery
of the transplanted
heart (arrow).
EXAMINATION PROTOCOL
Scanner
SOMATOM Definition
Scan area
Aortic arch to diaphragm
Scan length
205 mm
Scan time
16.3 s
Scan direction
Cranio-caudal
Heart rate
Arrhythmic 45–125 bpm
kV
120 kV
Effective mAs
400 mAs/rot
Rotation time
0.33 s
Temporal resolution
HR independent 83 msec
Slice collimation
0.6 mm
Spatial resolution
0.33 mm
Slice width
0.75 mm
Pitch
0.22
Reconstruction increment
0.4 mm
Kernel
B26
References
1 Cp. Chiu KM, Lin TY, Chu SH. Successful Heterotopic Heart Transplantation after Cardiopulmonary Bypass
Rescue of Arrested Donor Heart. Transplantation Proceedings 2006; 38: 1514–1515.
2 Cp. Chiu KM, Lin TY, Li SJ, Chan CY, Chu SH. Hybrid Pulmonary Artery Conduit Angioplasty for Heterotopic
Heart Transplantation. Transplantation Proceedings 2006; 38: 1538–1540.
31
Case 2
Reliable In-Stent Lumen Visualization
With Dual Source CT Coronary Angiography
By Annick C. Weustink, MD, and Nico R. Mollet, MD, PhD,
Departments of Radiology and Cardiology, Erasmus Medical Center, Rotterdam, the Netherlands
HISTORY
A 58-year-old man with a history of hypertension and hypercholesterolemia was
admitted to the hospital with symptoms
of suspected stable angina pectoris.
The patient was referred to conventional
coronary angiography after a positive
exercise-ECG test. Conventional angiography showed significant stenoses at the
level of the proximal right coronary artery
(RCA) and the proximal left anterior descending coronary artery (LAD). Percutaneous intervention was undertaken and
one bare-metal stent in the RCA and two
overlapping bare-metal stents in the LAD
were successfully implanted. The patient
was referred to follow-up CT coronary
angiography after 18 months.
DIAGNOSIS
The patient was scanned on a Dual
Source CT (DSCT) scanner. Nitroglycerine
was administered prior to the CT scan;
however, the patient did not receive prescan beta-blockers. The patient had a
heart rate of 76 beats/minute during the
CT scan. DSCT coronary angiography was
able to reliably rule out the presence of
in-stent restenosis in both the RCA and
LAD stents.
COMMENTS
The SOMATOM® Definition CT scanner
uses two X-ray sources and two detectors
at the same time. This is one of the important features for cardiac CT scanning. It
allows scanning of the heart with a heart-
rate-independent temporal resolution of
83 ms. As a result, high-quality images of
the rapidly-moving coronary arteries are
obtained even with higher heart rates.
Moreover, the adaptive pitch and
use of prospective ECG-tube modulation
allows significant reduction of the radiation exposure during cardiac CT scanning,
especially with higher heart rates. This
example shows clear delineation of the
stents with excellent visualization of
the in-stent lumen without the need for
pre-scan beta-blockers in a patient with
a heart rate of 76 beats/minute. It demonstrates the potential of DSCT coronary
angiography to rule out the presence of
in-stent restenosis in follow-up patients
after percutaneous intervention procedures.
Scanner
SOMATOM Definition
Scan area
Heart
Scan length
103 mm
Scan time
7,3 sec
Scan direction
Caudo-cranial
Heart rate
76 bpm
kV
120 kV
mAs / Rot
400 mAs/rot
Rotation time
0.33 sec
Temporal resolution
Slice collimation
0.6 mm
Spatial resolution
0.33 mm
Pitch
0.32
Reconstructed slice thickness
0.75 mm
Increment
0.4 mm
Prospective ECG-tube modulation
On, window: 30 – 60%
CTDIvol
45,31 mGy
Kernel
B46f
Contrast material volume
90 ml
Flow rate
5,5 ml/s
Bolus tracking
On
1
1 Volume Rendered CT image showing the stents in the proximal-to-mid LAD and the mid part of the RCA.
2
3
2 3 Curved multiplanar CT images showing excellent visualization of the in-stent lumen of both the RCA
(Fig. 2) and LAD (Fig. 3) stents, thereby reliably ruling out the presence of in-stent restenosis.
33
Case 3
SOMATOM Definition Abdominal CTA
With Direct Dual Energy Bone Subtraction
By Alec J. Megibow MD, MPH, FACR and Johnny Vlahos, MD, Department of Radiology, NYU Medical Center, New York, USA
HISTORY
DIAGNOSIS
COMMENTS
A 75-year-old man was referred for presurgical MDCT evaluation of a known abdominal aortic aneurysm that had been
detected on screening abdominal ultrasound. A contrast enhanced CTA scan of
the abdomen was performed on the
SOMATOM® Definition.
The acquisition parameters allowed precise localization of the origin of the aneurysm with respect to the renal arteries
and allowed for necessary measurements
of the neck of the aneurysm, the distance
from the renal arteries to the aortic bifurcation and to each common iliac bifurcation to be calculated, and the adequacy of
the run-off to the lower extremities to be
assessed. Finally, a small accessory
renal artery supplying the upper pole of
the right kidney was detected. Based on
this single study, the patient was considered a candidate for endovascular repair.
The scanning protocol (outlined below)
utilized the Definition’s dual x-ray sources,
each operating at a different kVp thereby
resulting in a simultaneous dual energy
acquisition. Two spiral data sets are
acquired in a single acquisition; each data
set contains unique spectral information,
which allows differentiation and characterization of imaged structures and tissue
(Fig.1). In this dual energy application,
the direct subtraction of bone can be
achieved almost instantly with a high
degree of accuracy as compared with
conventional bone removal techniques.
1
1 Precise visualization of the abdominal
aneurysm and their relations to
skeletal landmarks is possible with
the SOMATOM Definition.
Additionally, critical small vessels such as
an accessory right upper pole renal artery
can be easily preserved. Using dual energy acquisitions, abdominal CTA segmentations can be performed, eliminating
manual post processing steps and thereby significantly reducing reporting time.
The degree of bone segmentation is at
the discretion of the radiologist; in this
example, the dual display allows the vascular map to be superimposed over the
skeletal structures. This aids the surgeon
in establishing landmarks that can aid in
the fluoroscopic based endovascular repair. The success of the bone removal is
illustrated in the MIP image (Fig. 2).
Scanner
SOMATOM Definition
Scan area
Abdominal CT Angiography
Scan length
410 mm
Scan time
12 sec
Scan direction
Caudo-cranial
kV
140 kV and 80 kV
Effective mAs
66 eff. mAs and 190 eff. mAs
Rotation time
0.5 sec
Slice collimation
0.6 mm
Spatial resolution
0.33 mm
Slice width
2 mm
2 mm
Increment
1.5 mm
CTDIvol
10.7 mGy
Kernel
D20f
Contrast material volume
100 ml
Flow rate
4 ml/s
Bolus tracking
On
2
3
2 Dual Energy MIP of the abdominal vasculature allows
immediate rule out of aneurysms, stenosis or embolism.
Notice the lack of interference from bones.
3 Dual Energy VRT, excellent visualization of the abdominal skeleton.
35
Clinical Outcomes Oncology
NEW: syngo CT Oncology
Designed to Take the Guesswork out of Routine
Oncology Imaging!
By Louise A. McKenna, PhD, MBA, Global Clinical Marketing Manager, CT Oncology,
Siemens Medical Solutions, Forchheim, Germany
Siemens’ newest software for routine CT
oncology imaging, syngo® CT Oncology,
has radiologist’s daily needs in mind. Designed to take the guesswork out of routine lesion evaluation, syngo CT Oncology** offers automated tools for tumor
evaluation including automated measurement of RECIST and WHO criteria, lesion
volume plus tumor burden. Fully automated lesion matching speeds up the follow-up process with automatic generation
of percentage-growth and doubling time
helping to improve reliability and confidence. The new software offers dedicated
workflows, so called autopilots, for the
evaluation of lung and liver lesions, plus
lymph nodes.
For the identification and evaluation of
lung lesions, the lung autopilot incorporates Siemens’ clinically proven Lung
CAD* software with auto-preprocessing.
This means that as soon as the reconstructed image data arrives at the syngo
workplace, potential lesions are automatically detected off-line and the results are
ready to review when the radiologist
opens the exam, saving valuable time and
enhancing diagnostic confidence. Oneclick lesion segmentation results in automatic generation of standard tumor eval-
uation parameters such as RECIST, WHO
and tumor burden, plus the 3D volume.
The DICOM SR (and RT) compatible report
can be saved to PACS for follow-up. For
follow-up exams, automated lesion matching helps the clinician to locate previously identified lesions quickly and easily.
Previously generated lesion size parameters are instantly available for comparison, growth is automatically calculated
and the results are presented in an intuitive tabular form (Fig.1).
syngo CT Oncology lymph node evaluation uniquely offers clinician a fully automated workflow for the evaluation of
lymph nodes. One-click 3D-segmentation
of user identified lymph nodes results in
automatic calculation of the RECIST, WHO
and volume measurements. Lesion details
are automatically saved to a DICOM SR
and can be used for fast, accurate followup for staging and treatment monitoring
(Fig.2).
“This software presents considerable opportunities for improvement of diagnostic
outcomes”, explains Axel Küttner MD,
Department of Diagnostic Radiology, University of Erlangen-Nuremberg, Erlangen,
Germany. “In a recent follow-up exam, an
enlarged lymph node was identified as
suspicious. Automated lesion matching
assisted in the rapid identification of the
same, very much smaller lymph node in
the previous exam. The automated measurement should also help to further reduce reader variability, enabling us to
achieve even better diagnostic outcomes”.
The evaluation and follow-up of liver
lesions follows the same automated workflow as for lung lesions and lymph nodes,
helping to ensure easy integration of this
software into daily clinical routine diagnostic oncology imaging, staging
and follow-up (Fig.3).
syngo CT Oncology also incorporates
image fusion functionality for example for
PET-CT imaging, with fully automated image registration, clinicians can readily
match form with function helping to
achieve more confident diagnostic decisions.
syngo CT Oncology will be available with
syngo 2008A software in September 2007.
*syngo Lung CAD is not designed to be used as a
first-reader.
**Pending 510(k): The information about this
1
1 Follow-up of a
lung lesion. Growth
parameters are
generated at the
touch of a button.
A comprehensive results
table includes growth
parameter for all lesions
including doubling time
and tumor burden.
Courtesy of Marco Das, MD,
RWTH Aachen, Germany.
Oncology Clinical Outcomes
2
2
2
2 Identification and follow-up of lymph nodes
(follow-up exam on the left).
Courtesy of Axel Küttner, MD, University of Erlangen-Nuremberg,
Erlangen, Germany.
3 Follow-up of a liver lesion.
Courtesy of Anno Graser, MD, University Hospital of MunichGrosshadern, Munich,, Germany.
3
3
37
Clinical Outcomes Oncology
Case 4
Improved Evaluation and Follow-up
of Routine Diagnostic Oncology Exams
With syngo CT Oncology*
By Axel Küttner, MD, and Alexander Aplas, MD, Institute of Diagnostic Radiology, University of Erlangen-Nuremberg,
Erlangen, Germany
Diagnostic, staging and follow-up exams
for tumors are among the most frequent
CT exams performed in many radiology
departments. For the University of Erlangen, oncology related imaging represents
approximately 60% of the daily CT workload. To date, exams are read and evaluated in 2D, employing manual measurement and reporting of lesions. For
follow-up exams, previously reported lesions must be manually located, and are
often re-measured for size comparison
with the current exam. This relatively
time-consuming manual process is therefore prone to intra- and inter-reader variability, with the potential for sub-optimal
outcomes.
1
1 Identification of 3 intraabdominal lesions
and 1 of 2 lung lesions
marked for 3 month
follow-up. Lesions can
be viewed in axial,
coronal, sagittal and
VRT views. Basic lesion
parameters are
presented in a DICOM
SR compatible report.
Lung lesions were
identified in the same
dataset by switching to
a lung window.
38
Recently a number of automated or semiautomated 2D/3D, and CAD software
tools have become available to assist in
the evaluation, reporting and follow-up
of lung and colon lesions. These have
proved extremely useful in improving diagnostic outcomes, delivering reliable
performance in everyday clinical routine
– increasing reader confidence and shortening evaluation time.1–3 However, these
automated tools do not cover the evaluation of lymph nodes and liver nodules,
for example, which together with the
evaluation of lung lesions are the bread
and butter imaging of clinical routine.
syngo® CT Oncology* is a new software,
which offers automated workflows for
1B
the 3D evaluation and follow-up of tumors
in the liver and in the lung, incorporating
lung CAD. There is also a dedicated algorithm for lymph nodes, plus a generic
algorithm for other tumors throughout
the body – such as malignant melanoma,
as in the case presented here.
HISTORY
A 70-year-old man underwent a routine
follow-up CT exam at three months while
undergoing chemotherapy for malignant
melanoma. The software facilitates 3D
lesion segmentation and delivers standard lesion parameters: RECIST, WHO and
volume (Fig. 1). The automated lesion
Oncology Clinical Outcomes
3
Scanner
3 Significantly increased tumor burden is
marked in red in the report. The percental change in RECIST, WHO, 3D volume
and doubling time of all lesions are
automatically calculated and included
in the DICOM SR compatible report.
matching marked previously reported lesions in the follow-up exam and the percental change in lesion parameters were
automatically calculated and sent to the
DICOM SR (Fig. 2). Doubling time and
tumor burden are also automatically calculated and as a useful eye catcher, tumor burden is highlighted in red, demonstrating significant growth of marked
SOMATOM Sensation 64-slice configuration
Scan area
Thorax-Abdomen
Pitch
1.2
Scan length
686 mm
0.8 mm
B4If
Scan time
15 s
Kernel
Scan direction
cranio-caudal
Contrast
kV
120 kV
Volume
100 ml
Effective mAs
150 mAs
Flow rate
3 ml / s
Rotation time
0.5 s
Postprocessing
Slice collimation
0.6 mm
syngo CT Oncology
Spatial resolution
0.33 mm
Slice width
1 mm
lesions (Fig. 3). A great time saver is the
ability to switch between lung and soft tissue windows, for example, which means
that lung nodules (Figs. 1 and 2) can be
easily evaluated at the same time, without
loading a new data set. All lesion parameters are included in the same report.
DIAGNOSIS AND COMMENTS
Preliminary experiences with syngo CT
Oncology** suggest a great potential for
improving all aspects of routine workflow
by allowing us to deliver objective, reliable and consistent tumor evaluation and
follow-up measurements which are less
prone to inter- and intra-reader variability, allowing us to deliver a more standardized output. Additionally, the automated lesion matching could help to save
valuable time in follow-up exams.
1 Graser, A. and Becker, C. R. (2005)
SOMATOM Sessions 17.
2 Das, M. et al (2006) SOMATOM Sessions 19.
3 Mang, T. et al (2007) Eur Radiol Mar 10.
* syngo CT Oncology will be available with the
release of syngo 2008A.
** Pending 510(k): The information about this
2
2 Automated lesion
matching identified the
previously identified
lesions in the follow-up
exam. The percental
change in basic tumor
parameters were automatically calcu-lated and
presented in the report.
39
Clinical Outcomes Neurology
Case 5
Utilizing the SOMATOM Emotion 16-slice
configuration for a Neuro DSA CTA Evaluation
of a Suspected PICA Aneurysm
By Adam J. Davis, MD, Hartsdale Imaging, Hartsdale, New York, USA
HISTORY
DIAGNOSIS AND COMMENTS
The patient, a 13-year-old female presented in our Imaging Center with
acute onset persistent left hemicranial
and left supraorbital headache. Neurologic examination was unremarkable.
A non-gadolinium 3D TOF MRA of the
brain was performed to evaluate for the
possibility of a vascular abnormality.
The exam was suspicious for a left posterior inferior cerebellar artery (PICA) saccular aneurysm. CTA of the brain was
requested for a further evaluation.
A left posterior inferior cerebellar artery
loop was diagnosed and no aneurysm
demonstrated.
MRA is an excellent screening technique
for the presence of intracranial aneurysms,
although the inherent resolution and
presence of flow artifacts may make the
technique insufficient for smaller and
more tortuous intracranial vessels. The
MRA imaging is suspicious, but not definitive, for a proximal left PICA aneurysm.
An elongated 2.9 mm posterior projecting
outpouching could not be clearly delineated from the parent vessel. The Neuro
DSA CTA of the brain clearly defined the
anatomy of the vessel, demonstrating a
tight, posteriorly oriented C-shaped loop,
1
Scanner
L
R
corresponding to the area of suspicion
on the MRA. The fully automated CT DSA
application easily allowed VRT visualization of the origin of the PICA from the lateral aspect of the vertebral artery, normally obscured by the adjacent occipital
bone. Of interest, differing algorithms
provide a different visualization of the
anatomy. The use of a higher kernel algorithm for the pre- and post-masks allows
for a more definitive evaluation of the
luminal contour, although the image
quality may be less pleasing to the eye.
It should be remembered that the luminal
diameter of this PICA measures approximately 0.6 mm; emphasizing the excellent inherent resolution of Neuro DSA
CTA performed with the SOMATOM®
Emotion 16-slice configuration.
SOMATOM Emotion 16-slice configuration
Scan area
Head
Slice collimation
0.6 mm
Scan length
138 mm
Slice width
0.75 mm
Scan time
10 s
Pitch
0.9
Scan direction
Caudo Cranial
0.5mm
kV
130 kV
Kernel
H20 / H70
Effective mAs
176 mAs
Postprocessing
Rotation time
0.6 s
syngo Neuro DSA
1 PA view of the non-gadolinium 3D TOF
MRA demonstrates the abnormality
at the origin of the left PICA (arrow).
Neurology Clinical Outcomes
2
3
,
2 A more magnified MRA image utilizing clip planes isolates the left PICA. The best view orientation gives a
hint as to the true nature of the finding, although
the vessel course and origin are not clearly defined
on the MRA, and the outpouching cannot be entirely
eliminated in any view. The study remains non-diagnostic.
4
3 CTA utilizing a closely applied clip plane from the left
side eliminates much of the obscuring occipital
calvarium, and allows improved visualization of the
lateral aspect of the vessel. While still somewhat
obscured, this view demonstrates the origin of the
PICA and a tight posterior C-shaped loop, not an
aneurysm (H20 S Kernel setting).
5
4 Neuro DSA CTA provides a rapid and easy to acquire
visualization of the lateral aspect of the left PICA.
A clip plane in the orientation of the view was the
only additional post processing required once the
VRT was created. The vessel loop is clearly defined,
and the possibility of a saccular aneurysm is definitively excluded (arrow).
5 Neuro DSA CTA utilizing a higher kernel algorithm
(H70s) provides substantially better visualization of
the origin of the left PICA. A well defined proximal
segment is now seen prior to the tight posterior
C-shaped loop (arrow). The contralateral right PICA is
also clearly defined (arrowhead).
41
Clinical Outcomes Acute Care
Case 6
Dual Source CT Triple Rule Out
Without Beta-Blocker
By Christoph R. Becker, MD, Section Chief, Computed Tomography
Department of Clinical Radiology, University Hospital of Munich-Grosshadern, Munich, Germany
HISTORY
A 60-year-old male patient, suffering
from a severe chest pain, arrived in the
Department of Radiology of the University Hospital in Munich, Großhadern. In
order to rule out the major causes of
chest pain (such as myocardial infarction,
pulmonary embolism, and aortic dissection) in a one stop diagnosis, the patient
was transferred directly to the CT department. A gated scan of chest was performed on the SOMATOM® Definition,
without the use of beta-blockers.
the major causes of chest pain in a onestop diagnosis without the compromise
of beta-blockers. Now we can accurately
triage chest-pain patients within 10 minutes after presenting to our department.
With the SOMATOM Definition, a special
Chest Pain protocol can be used, applying reduced dose to the patient through
the combination of two scan ranges,
a cardio scan and a thorax scan. The dose
modulation along the patient axis is performed with an optimized dose for each
of the corresponding regions. In combination with a simple contrast injection
protocol of 80 ml with a flow rate of
4,5 ml/s, Dual Source CT enabled us to
establish the chest pain evaluation into
our daily routine.
DIAGNOSIS
The gated chest pain protocol of the
SOMATOM Definition enabled the immediate visualization of the entire thorax
as well as the coronary arteries without
motion artifacts. As shown in the images
below, a Stanford type B aortic dissection
was identified. The patient was referred
to Vascular Surgery Department for stent
placement.
COMMENTS
Chest pain is one of the most common
and complex symptoms for which patients
seek medical care. With standard diagnostic evaluation, patients with chest pain
undergo multiple serial tests and long
observation periods. This ties up staff as
well as space for up to a whole day. Dual
Source CT enables us to quickly rule out
Scanner
SOMATOM Definition
Scan area
Chest
Scan length
285 mm
Scan time
16 sec
Scan direction
Cranio-caudal
Heart rate
65–70 bpm
kV
120 kV
mAs/Rot
320 mAs/Rot
Rotation time
0.33 sec
Temporal resolution
Slice collimation
0.6 mm
Spatial resolution
0.33 mm
Slice width
0.6 mm
Pitch
0.30
0.75
Effective dose
9,2 mSv
Kernel
B26
Volume
80 ml
Flow rate
4,5 ml/s
Start delay
CareBolus+5s
Acute Care Clinical Outcomes
1
3
2
1 Motion free visualization of coronary
arteries rule out myocardial infarction.
2 Due to excellent imaging of patient’s aorta,
Stanford type B aortic dissection can be precisely
shown.
3 Accurate display of pulmonary arteries
rule out pulmonary embolism.
43
Clinical Outcomes Acute Care
Case 7
SOMATOM Definition: New Insight Into
Kidney Stone Detection and Characterization
With Spiral Dual Energy
By Anno Graser, MD, Thorsten Johnson, MD, and Christoph R. Becker, MD,
Department of Clinical Radiology, University Hospital of Munich-Grosshadern, Munich, Germany
HISTORY
DIAGNOSIS
A 34-year-old male (Fig. 1A) and a 55year-old male with latent gout (Fig. 1B)
separately visited our Acute Care unit
with flank pain. They had been presented after multiple occurrence of nephrolithiasis and urolithiasis. Both patients
were referred to our Dual Source CT
for evaluation of abdominal stones.
Contrast enhanced CTA scans of the
abdomen were performed on the
SOMATOM® Definition using spiral dual
energy.
The dual energy acquisition allowed precise localization of the kidney stones.
In addition Patient B showed dilatation
of the right ureter proximal to the calculus. Moreover, dual energy analysis
permitted a characterization of the
scanned tissue or material. The red colorcoding of the urethral stone shown in
Patient A (Fig. 2A) indicates an uric acid
stone. In contrast, the vertebrae can be
identified as blue-colored structure. After
Dual Energy CT, we could transfer the pa-
1A
tient for drug therapy treatment. Subsequently, the stone passed spontaneously
and was analysed. The analysis confirmed
that the concrement consisted of 100%
uric acid.
The blue color-code shown in Patient B
(Fig. 2B) characterizes a calcium oxalate
stone. Based on this dual energy study,
the stone was removed in an interventional procedure. The lab analysis of the
removed stone confirmed the calcium
oxalate composition.
1B
1 Using conventional MDCT imaging, urethral stones (arrows) can clearly be visualized in both patients
(Fig. 1A and 1B). However, they cannot be characterized based on a conventional CT single source image.
44
Acute Care Clinical Outcomes
Scanner
SOMATOM Definition
SOMATOM Definition
Patient
Patient A
Patient B
Scan area
Abdominal Scan
Abdominal Scan
Scan length
377 mm
215 mm
25 sec
Scan time
44 sec
Scan direction
Craniocaudal
Craniocaudal
kV
140 kV and 80 kV
140 kV and 80 kV
Effective mAs
Rotation time
0.5 sec
0.5 sec
Slice collimation
0.6 mm
0.6 mm
Spatial resolution
0.33 mm
0.33 mm
Slice width
0.75 mm
0.75 mm
2.0 mm
2.0 mm
Increment
1.5 mm
1.5 mm
CTDIvol
18.07 mGy
15.4 mGy
Kernel
D30
D30
CareDose4D
on
on
COMMENTS
The majority of kidney stones can be
grouped as either calcium oxalate stones
(80%) or uric acid material (9%). Conventional CT imaging helps to locate and visualize kidney stones. However, a fast and
secure characterization is not possible.
Dual energy scanning overcomes this limi-
tation and enables us to differentiate the
scanned tissue. The SOMATOM Definition
permits the use of two sources at two different kV levels simultaneously. The result
is two spiral data sets acquired in a single
scan providing diverse information, making it possible to differentiate, character-
2A
2B
2A Patient A: Spiral dual energy enables the characterization of
tissue. The kidney stone could be identified as uric acid stone,
color-coded in red (arrow).
2B
ize, isolate, and distinguish the imaged tissue and material as shown in Fig. 2A and
2B. In our case, dual energy scanning offers new insights into the characterization
of urolitis. A corresponding treatment decision can be reached immediately, avoiding
unnecessary hospitalization.
Patient B: Spiral dual energy enables the characterization of
tissue. The kidney stone could be identifies as calcium oxalate
stone, color-coded in blue (arrow).
45
Science
Dual Source CT
Detecting Coronary Atherosclerosis
by Dual Source Computed Tomography Images
With Color Maps
By Sei Komatsu1,2, Dieter Ropers1, Axel Küttner3, Ulrike Ropers1, Martin Wechsel1, Tobias Pflederer1, Alexander Kuhlmann1,
Katharina Anders3, Werner Bautz3, Werner G. Daniel1, Atsushi Hirayama2, Kazuhisa Kodama2, Stephan Achenbach1
Department of Internal Medicine 2, University of Erlangen-Nuremberg, Erlangen, Germany
Cardiovascular Division, Osaka Police Hospital, Osaka, Japan
3
Institute of Diagnostic Radiology, University of Erlangen-Nuremberg, Erlangen, Germany
1
2
Color-coded Coronary
Analysis
Recently, Dual Source computed tomography (DSCT) has become available. Due
to its high temporal resolution, coronary
arteries can now be visualized with reduced motion artifacts. Spatial resolution
of DSCT reaches 0.33 mm allowing more
precise visualization of the coronary
arteries. However, the grade of stenosis
does not predict an acute coronary syndrome 1 due to positive remodeling (compensatory enlargement of lumen area 2).
Multi-detector row CT (MDCT) coronary
angiography allows noninvasive visualization not only of coronary stenosis but also
of coronary atherosclerosis 3–5. Plaque
composition such as lipid-rich plaque, fibrous plaque, and calcified plaque can be
characterized based on the CT values 4,5.
Region of interest (ROI) and profile curve
are traditional methods to measure CT
values. However, they do not cover the
entire vessel at one time. We developed a
1A
comprehensive method of analysis,
Plaque Map, which converts DICOM-formatted files to color-coded images based
on CT attenuation5. Vulnerable plaque of
coronary 6,7 and peripheral arteries8 can be
demonstrated by MDCT using Plaque Map
as IVUS-like visualization tool. Fig. 1 demonstrates a typical example. Fig. 1A is a
cross-sectional image of a vessel without
plaque. Concentric graduation from red to
yellow spreads outwards the vessel. Fig.
1B is a cross-sectional image of the culprit
lesion in a patient with acute coronary
syndrome. Yellow area (dotted arrow)
2
1C
1A
1A Cross-sectional image of
vessel without plaque (Left).
Plaque Map (Right). Concentric graduation from red to
yellow spreads outside the
vessel.
50
0
200
350*
100
White
0
68
136
273
341
409
*Maximum CT number of
Contrast Media
1B (Quoted ref 7) The cross-sectional image of acute corona
areas drawn green to blue
(arrow) are ranged -25 to 25
HU, suggesting lipid-rich
plaque.
1B
205
Lipid-rich Plaque (LP)
Fibrous Plaque (FP)
Calcified Plaque (CP)
1C (Quoted ref 7) Intravascular
ultrasound image. Plaque
Map corresponded to the
findings of intravascular
ultrasound (IVUS).
1C
500
350
300
250
200
150
70
–(HU)
– 500
– 350
– 300
– 250
– 200
– 150
50
25
0
-25
-50
– 70
– 50
– 25
~ 0
~ -25
~ -50
2 Color Map for
detecting plaque
characteristics.
3A
4A
4B
5A
5B
b
c
d
LP
lipid pool
3B
4C
5C
5D
FP
LP
branch
CP
LP+FP
3 Color Map of curved
MPR of normal coronary
artery (Fig. 3A). Crosssectional image of Fig.
3A arrow (Fig. 3B).
0–50
50–100
4 An example of non-calcified
plaque. Fig. 4A: Curved MPR.
Fig. 4B: Color-coded curved MPR.
Fig. 4C: Color-coded cross-sectional image at Q1 (Fig. 4B dot).
100–200
200–500
0–50
50–100
represents residual lumen area which
indicates a severe stenosis. Three areas
with green to blue color (arrow) ranging
from -25 to 25 HU, suggest lipid-rich
plaque. The observation of predominantly lipid-rich plaque corresponds well to
IVUS (Fig. 1C). Recently the syngo Circulation software package has been equipped
with color-coded analysis based on CT
attenuation 9 (syngo Circulation Plaque
Analysis). We describe one application
for detecting coronary plaque.
Screening Coronary Plaque
using syngo Circulation
The integrated color coding allows the
four colors, green, light green, orange,
and pink. The ranges and thresholds
can be individually changed. We set the
borders of the scale to distinguish maximum six borders through coronary
artery; transparent (below 0 HU), green
(0–50 HU), light green (50–100 HU),
orange (100 –200 HU), pink (200-“maximum CT number of contrast media on
coronary artery”), and white (above “maximum CT number of contrast media”)
(Fig. 2). The upper limit of pink area is the
same as contrast media. Light green and
orange correspond to fibrous plaque. Green
shows lipid-rich plaque. Lipid-pools are suspected of areas with a density below 0 HU
inside the vessel area. CT density of calcification is above the maximum CT number
of contrast media, appearing white.
100–200
200–500
5 An example of various plaque types. Color Map of curved MPR
(Fig. 5A). The points b, c and d in Fig. 5A are shown as Fig. 5B,
Fig. 5C, and Fig. 5D, respectively. LP: lipid-rich plaque, FP: fibrous
plaque, CP: calcified plaque.
0 –50
50 –100
100–200
200–350
Interpretation of Coronary
Plaque with Color Analysis
Futures of Color Analysis
using DSCT
A typical vessel without plaque is demonstrated in Fig. 3A. Areas of orange, light
green and green are demonstrated as
concentric circles (Fig. 3B). A typical
example of lipid-rich plaque is shown in
Fig. 4. The curved MPR of left anterior
descending coronary artery shows a noncalcified plaque with positive remodelling
in the proximal segment of the coronary
artery (Fig. 4A). Fig. 4B and 4C, respectively, demonstrate color maps of the
curved MPR and cross-sectional image at
the level of the atherosclerotic lesion.
Green, which ranges from 0 to 50 HU,
and light-green, which ranges from 50 to
100 HU, are dominant. This suggests that
the plaque consists of predominantly
lipid-rich components.
We also show another example of various
plaque types. The left anterior descending artery of an asymptomatic patient
was analyzed (Fig. 5). Cross-sectional images at the points b, c and d in Fig. 5A
are shown as Fig. 5B, Fig. 5C, and Fig. 5D,
respectively. In Fig. 5B, lipid-rich plaque
as light green is present at 3–6 o‘clock
position of the vessel. In the vessel, area
less than 0 HU (transparent) is found at
5–6 o’clock, suggesting a lipid-pool.
Fig. 5C demonstrates calcified plaque in
white. Fig. 5D shows mixed plaque in light
green and green, suggesting a mixture
of fibrous and lipid-rich plaque.
Previously, analysis of CT attenuation
within coronary atherosclerotic plaques
was limited by the relatively poor spatial
resolution of CT. CT attenuation was used
for “organ-level” analysis. The improvement of spatial and temporal resolution
of DSCT minimizes partial volume effects
and “Pixel analysis in silico”7 becomes
possible. The term “in silico”, referring to is
commonly used in the fields of life science
and computer medicine. In the era of
DSCT, we can analyze plaque at “tissuelevel” using a workstation with color coding software such as syngo Circulation.
References
1 Ambrose JA et al. J Am Coll Cardiol 1988: 12(1):
56–62.
2 Glagov S et al. N Engl J Med. 1987: 316(22):
1371–5.
3 Schroeder S et al. J Am Coll Cardiol. 2001: 37(5):
1430–5.
4 Achenbach S et al. Circulation. 2004: 109(1): 14–7.
5 Komatsu S et al. Circ J 2005: 69(1): 72–7.
6 Komatsu S et al. Int J Cardiol 2007: 117(3): 423-9.
7 Komatsu S et al. Vascular Disease Prevention 2006:
3(4): 319–325.
8 Komatsu S et al. Int J Cardiol 2007: 117(3):423-9.
9 syngo Circulation: The Next generation.
SOMATOM Session 18. 8–9, 2006.
47
Science
Coronary CT Angiography With DSCT
Implications for Contrast Media Delivery
By Joachim Ernst Wildberger, MD1, Andreas Horst Mahnken, MD, MBA1, and Peter Reinhardt Seidensticker, MD2
Department of Diagnostic Radiology, RWTH Aachen University, Aachen, Germany
2
Global Medical Affairs Diagnostic Imaging, Bayer Schering Pharma AG, Berlin, Germany
1
Implications for
Contrast Media Delivery
Multi-detector row computed tomography
(MDCT) has substantially improved over
the past years with faster gantry rotation,
more powerful X-ray tubes, dedicated interpolation algorithms and – last but not
least – the introduction of Dual Source
CT (DSCT) with the SOMATOM Definition
(Siemens Medical Solutions, Forchheim,
Germany) in 2006.
As one of the consequences of this technical evolution, CT angiography (CTA)
of the coronaries has become an established technique for minimally invasive
imaging and has already replaced a significant number of diagnostic catheter
angiographies. Fundamental advantages
of the new DSCT scanners are provided
by three cornerstones, i.e., improved
spatial resolution, better temporal resolution and shorter scan time.
With DSCT, imaging of the coronaries
can easily be performed in a single breathhold providing sub-millimeter isotropic
resolution and minimized motion artifacts.
High quality assessment of the coronary
vessels highly irrespective of the underlying heart rate of the patient is an evolutionary milestone that significantly improves the clinical robustness of cardiac CT.
Contrast Media Administration
In general, optimized contrast injection
is an important issue for achieving high
quality CT scans with homogeneous attenuation and high contrast throughout
the entire data set. In particular CT angiography, including cardiac CT, will benefit
from homogeneous and compact bolus
geometry1. High and constant iodine contrast should be maintained throughout
the whole data set to achieve diagnostic
opacification by providing optimal contrast
between the vessel lumen and the surrounding soft tissue.
Scanner
SOMATOM Definition
Collimation
2 x 64 [2 x 32] x 0.6 mm
Pitch
Dependent on patient’s heart rate (0.2 – 0.43)
kVp
120
mAsrot
400*
Rotation time
330 ms
Slice thicknesseff
0.75 mm
Increment
0.4 mm
Kernel
Siemens B26f (HeartView smooth ASA)
Contrast media injection protocol
IDR (Iodine Delivery Rate)
biphasic (5 s @ 2 gJ/s + (x-5) s @ 1.5 gJ/s)**
(e.g. Iopromide 370: 27 ml @ 5.4 ml/s + y ml @ 4 ml/s
Iopromide 300: 33 ml @ 6.6 ml/s + y ml @ 5 ml/s)
Amount
Individually adapted: Injection duration = Scan duration + 10%
Saline chaser
50 ml @ 4 ml/s (370) and 5 ml/s (300), respectively
Bolus timing
Bolus-Trigger in the ascending aorta; Threshold: 180 HU
Scan parameters, reconstruction parameters and contrast injection parameters for a suggested cardiac scan protocol
with the SOMATOM Definition (Siemens).
* In addition, a dose modulation concept is recommended (e.g. Care Dose 4D; ECG-pulsing).
** x = (Scan duration + 10%); Clinical example: Contrast material will be injected with 2g iodine/s , followed by a 6s injection at 1.5g iodine/s, if the scan lasts 10s.
The latter can be calculated from the overall injection duration; e.g. overall scan duration +10% = 11s, minus 5s for the first (fixed) injection phase. Therefore,
using iopromide 300, 33 mL will be injected with 6.6 mL/s followed by 30 mL iopromide 300 with 5 mL/s.
Science
1A
1B
1 Male patient with intermittent atypical chest pain and an increased cardio-vascular risk profile. He has a history of smoking (30 pack years)
and moderate hyperlipidaemia. Contrast-enhanced DSCT of the coronary arteries was performed to rule out coronary artery disease.
Fig. 1A: 3D-VRT (Volume Rendering Technique) shows the left coronary artery without pathological findings.
Fig. 1B: Curved multiplanar reformat (MPR) of the right coronary artery shows an eccentric, non-calcified plaque without relevant lumen
narrowing (arrows).
49
Science
2A
2B
2 74-year-old male patient with
a history of coronary bypass
surgery: He presented with
acute chest pain and suspected
bypass graft occlusion. Contrast-enhanced cardiac DSCT
revealed two patent CABG (coronary artery bypass grafts)
to the LCX (left circumflex
artery) and the LAD (left anterior descending artery) (Fig.
2A). Distal anastomoses were
patent (arrows), as exemplarily shown for the LAD (Fig. 2B).
Science
Sophisticated injection protocols such
as biphasic injection protocols have been
advocated for coronary CT applications and
have been incorporated into the clinical
workflow. However, many complex multiphasic contrast delivery protocols for ideal
enhancement patterns are still based on
extensive mathematical equations and
have not yet undergone sufficient clinical
evaluation.2
Numerous factors affect the geometry of
the contrast medium bolus in CTA.3 These
factors may be divided into intrinsic patient related factors and extrinsic contrast
material and injection technique associated parameters, and include:
■ Patient cardiac output, individual pathology, specific parameters (e.g. body mass
index, blood pressure, heart rate and
even gender)
■ Specific pharmacologic features of the
contrast material itself (e.g. concentration, viscosity and temperature of the
contrast medium injected)
■ Injection technique (dual-head power injector; flow rate, total volume, mono-,
bi-, or multiphasic; use of saline chaser).
Iodine Delivery Rate (IDR)
The overall iodine load is the main determinant for parenchymal organ studies.
However, the overall amount of contrast
material administered to the patient is of
minor importance for a CTA study. The iodine delivery rate (IDR; given in g iodine/s)
is the determining factor for the quality
of the bolus and can easily be calculated
by multiplying the iodine concentration
of the contrast material (g iodine/ml)
with the flow rate of the injector (ml/s).
Usually the IDR will be in the range of
1.5 – 2.0 g iodine/s for CTA applications.
This can be realized by using a highly concentrated contrast medium (350 – 400 mg
iodine) in combination with moderate flow
rates. On the other hand, the same IDR can
also be achieved by increasing the flow
rates for contrast material with 300 mg of
iodine per ml (or even less). Normalizing
the IDR is a straightforward means of making different injection protocols comparable. It seems obvious that the choice of a
highly concentrated agent could keep the
flow rates lower and potentially could help
to avoid local complications such as paravasation. However, in this context it should
be kept in mind that the relation between
the iodine concentration of a contrast me-
dium and its viscosity is exponential. This
means that the pressures that are built up
by the power injector and the resulting
pressures in the patient‘s veins might be
even higher with highly concentrated
agents despite the fact that they are injected with slower flow rates. The clinical effect of different flow rates and contrast
medium viscosities on the incidence of
paravasation is not fully understood and
will require large prospective population
studies. However, the benefit of large access lines (e.g., 18G needles) and of preheating the contrast material to mean
body temperature of 37° Celsius in order to
bring down the viscosity appears obvious.
Scan Timing
In any case, using empiric scan delays
cannot be recommended with modern
MDCT or DSCT. With 16- (or more) slice
MDCT, the start delay of a CTA has to be
chosen individually. In the clinical setting,
two modes are currently available for optimal enhancement after intravenous contrast delivery1,4: Automated bolus tracking
provides a sufficiently robust, easy to use
method. A pre-monitoring scan is performed at the upper level of the heart using a low-dose scanning technique (120
kVp; 20 mAs (effective)). A region-of-interest is placed in the ascending aorta and
attenuation values (in Hounsfield units;
HU) are continuously measured during
the contrast injection. When the trigger
threshold level (e.g. 140 HU) is reached,
an automated start of the spiral scan is
initialized.
Alternatively, a test-bolus methodology
can be applied. A small additional volume
of contrast material (usually 15 ml – 20
ml) is injected at the same flow rates as
used for the contrast enhanced scan protocol. By repeat acquisition of serial scans
(monitoring scans every 2 s from approximately 10 s – 40 s; usually at the level of
the heart), individual flow dynamics can
be assessed more precisely: From the enhancement over time within the target
vessel lumen, the time-to-peak enhancement can be calculated. The latter is chosen as start delay. The test-bolus data also
allows estimation of the bolus geo-metry
with a given amount of contrast material
at a selected flow rate. Moreover, this
technique allows determination of cardiac
output from the contrast enhancement
curve and therefore constitutes a more in-
dividualized approach to the injection regimen as compared to automated bolus
tracking.5
Saline Chaser
The use of double-power injectors has
been advocated for automated saline
flushing at the injection site, especially for
CTA examinations. Otherwise, approximately 20 ml – 30 ml of contrast material
will be retained in the “dead space” between the brachial vein and the superior
vena cava. In consequence, performing
saline flush improves arterial enhancement and reduces the amount of contrast
needed for a diagnostic examination. This
has a positive impact on patient safety
and costs.6
In summary, optimal contrast bolus
shaping with special emphasis on bolus
design and timing is a key issue in modern
DSCT imaging of the coronary arteries. The
IDR is the most important factor for
achieving this goal and can be optimized
by adapting the flow rate of the injector to
the iodine concentration of the chosen
contrast medium. Typical IDRs lie between
1.5 g l/s and 2.0 g I/s. The test-bolus
methodology and automated bolus
tracking are widely used as an adjunct to
the regular CTA scan and help to increase
the robustness of this examination
method.
1 Cademartiri F., van der Lugt A, Luccichenti G,
Pavone P, Krestin GP. Parameters affecting bolus
geometry in CTA: A review. J Comput Assist Tomogr
2002; 26: 598 – 607.
2 Bae KT. Peak contrast enhancement in CT and MR
angiography: When does it occur and why? Pharmacokinetic study in a porcine model. Radiology 2003;
227: 809 – 816
3 Fleischmann D. High-concentration contrast media
in MDCT angiography: Principles and rationale.
Eur Radiol 2003; 13 Suppl 3: N39 – N43
4 Bae KT. Test-bolus versus bolus-tracking techniques
for CT angiographic timing. Radiology 2005; 236:
369 – 370.
5 Mahnken AH, Klotz E, Hennemuth A, Jung B, Koos
R, Wildberger JE, Günther RW. Measurement of cardiac output from a test-bolus injection in multislice
computed tomography.
Eur Radiol 2003; 13: 2498 – 2504.
6 Schoellnast H, Tillich M, Deutschmann HA,
Deutschmann MJ, Fritz GA, Stessel U, Schaffler GJ,
Uggowitzer MM. Abdominal multidetector row computed tomography. Reduction of cost and contrast
material dose using saline flush. J Comp Assist
Tomogr 2003; 27: 847 – 853.
51
Science
Nefertiti’s Bust – An Inside View
For decades, Nefertiti’s beauty has captivated museum visitors. But what is
behind the perfect surface? Modern CT technology increasingly becomes interesting for historical, non-destructive investigations. So plaster layers and the
limestone core of the world-famous bust can now easily be virtually separated
and evaluated.
By Andreas Blaha and Monika Demuth, PhD, Siemens Medical Solutions, Computed Tomography, Forchheim, Germany
The name of the Egyptian queen means
exactly what the bust shows: “the beautiful one has arrived.” And she has arrived –
or much better said, under extreme safety
precautions has been brought – in the
true sense of the word, to the Imaging
Science Institute (ISI) at Siemens Medical
Solutions in Berlin in order to be scanned
by the SOMATOM® Sensation 64-slice
computed tomography (CT) scanner. The
examination was part of a research for
documentation by the broadcaster, National Geographic, in cooperation with
Prof. Dietrich Wildung, Director of the
Egyptian Museum in Berlin. Thanks to
modern CT technology, the researchers
could make many inner details visible.
Because CT technology has realized such
tremendous advances since 1992 (when
the bust was last scanned) the researchers expected a much more detailed separation of the limestone core and plaster
surface of the bust revealing much more
detail due to the improved image quality
with 0,24 mm isotropic resolution of the
SOMATOM Sensation 64. The state of the
art volume rendering technique which
was used created 1660 thin axial cuts of
the bust. This enormous number of slices
have been put together to display a 3 dimensional object. This method is typically
used to view objects from all viewing angles to get a 3D impression of the object.
By adjusting the Houndsfield scale according to the scanned material it is possible
to show and hide the plaster layer over
the limestone and vice versa. In addition
it is possible to assign certain Houndsfield
values to colors for easy differentiation
between the displayed layers. Therefor
with help of CT software, it was possible
to virtually “remove” the plaster layer and
1
1 CT-image from a SOMATOM Sensation 64 showing the pristine surface
of the bust of Nefretete (without painting).
Science
then, step by step, dissect the limestone
core. The procedure revealed, in amazingly fine resolution, the rough limestone
core showing slanting, asymmetric shoulders and a thin throat (Figs. 2 and 3).
Discovering and establishing the practice
of non-damaging examinations of Egyptian antiques has been described by
Dietrich Wildung in 1992.1 He conducted
research according to the then-modern
archeological standards. Quite an unusual
idea at the time: spectacular findings
were then seldom thoroughly investigated by fine arts experts to the different
composition of the materials. The research with CT scans firmly established
that the composition consisted of a sculptured limestone core layered with plaster.
Plaster was used here and in other details
to modify the sculpture to the familiar
form known today.
Nofretete’s bust was discovered in 1912 at
the Egyptian desert village of Tell el-Amarna. Thanks to this world famous work by
the sculptor Thutmosis, the queen enjoys
worldwide recognition, not only by art experts, but also by the general public. As
wife of Pharaoh Echnaton, she and her
2
husband, in their function as priests, represented the important God, Aton. During
their rule, the royal couple often allowed
various portrayals of themselves with
their children.
Results and interpretations about the CTscan of Nefertitis bust will soon appear in
appropriate scientific publications.
Reference:
Dietrich Wildung, “Einblicke – Zerstörungsfreie
Untersuchungen an altägyptischen Objekten“,
1992, p 133–156.
1
3
2 This image shows the plaster layer over the shoulder area of the
limestone sculpture of the queen.
3 The limestone core of the bust, without plaster covering.
53
Science
CT Coronary Angiography
Half-Scan vs. Multi-Segment
Reconstruction for Computed Tomography
Coronary Angiography
Considerations on the effects on image quality
By Stephan Achenbach, MD, Department of Internal Medicine 2, University of Erlangen-Nuremberg, Erlangen, Germany
Coronary artery visualization by multidetector row (or better, multi-slice) computed tomography (“coronary CT angiography,“ “coronary CTA”) is rapidly entering
mainstream cardiology. High accuracies
have been reported for the detection
of coronary artery stenoses by 16- and
64-slice CT and especially a high negative
predictive value makes coronary CTA a
useful tool in the assessment of certain
patient populations with chest pain 1. In
a joint statement by several professional
societies, led by the American College of
Cardiology, the use of CT coronary angiography has been labeled an “appropriate” indication to rule out or establish the
presence of coronary artery stenoses in
several clinical situations 2.
Cardiac Motion
Rapid motion of the heart and coronary
arteries and ensuing impairment of image quality are the major problems that
may exist in CT coronary angiography. Insufficient image quality can lead to falsepositive or false-negative findings, with
the consequence of unnecessary further
testing in the first case and of missed
diagnoses in the latter. In order to avoid
artifacts caused by motion, two aspects
are important.
Firstly, with widely used single source
computed tomography systems it is
important to use data for image reconstruction that was acquired during a
cardiac phase of relatively little motion
of the coronary arteries.
Secondly, it is essential to limit data used
for image reconstruction to as short a
Reconstruction algorithms that use
data from one continuous 180° sweep of
the x-ray tube for image reconstruction
are called “half-scan” reconstruction algorithms. Thus, the temporal resolution of
these half-scan reconstruction algorithms
corresponds to approximately one-half
of the gantry rotation time (e.g. 330 ms
gantry rotation time = 165 ms temporal
resolution). All x-ray data used for reconstruction of a single cross-sectional image
are acquired contiguously during the
image acquisition window in one single
heart beat.
struct one single image. Theoretically,
the window of data used for image reconstruction in each cardiac cycle can be
substantially shorter than in half-scan
reconstruction algorithms. However,
multi-segment reconstruction algorithms
use data from several heart beats to reconstruct one image so that the generated
image is an “average” of several cardiac
cycles. Since slight differences from one
heart beat to the next can be assumed
even in regular heart rhythms, and since
substantial differences between consecutive heart beats must be assumed in situations e.g. of arrhythmia, the averaging
of several cardiac cycles has severe drawbacks from a theoretical point of view
(Fig. 1). A definite benefit of multi-segment reconstruction over half-scan reconstruction has not been proven for the
detection of coronary artery stenosis.
However, regarding the use of multi-segment reconstruction for coronary artery
visualization, potential issues of concern
exist. They will be outlined below.
Multi-Segment Reconstruction
(Multi-Phase Reconstruction)
1. Variability of the
Cardiac Cycle
Alternative approaches are so-called
“multi-segment” reconstruction algorithms. These algorithms use less than
180° of data from a single heart beat. To
compensate for the missing projections,
data acquired in the next cardiac cycles
is used to fill in the missing projections.
This is done under the assumption that
one cardiac cycle is absolutely equal
to the next and data from several heart
beats can thus be combined to recon-
Coronary artery visualization and analysis
requires sub-millimeter resolution. However, from one cardiac cycle to the next,
it cannot be expected that the coronary
arteries return to exactly the same position, within a fraction of a millimeter.
Thus, multi-segment reconstruction, which
uses averaging, may slightly blur the images and thus reduce image quality.
segment of the coronary cycle as possible. In order to reconstruct one cross-sectional image, data acquired from 180°
of parallel data projections are necessary.
Most computed tomography systems contain one x-ray tube, so that one-half rotation of the gantry is necessary to acquire
data from 180°.
Half-Scan Reconstruction
Science
1A
1B
1C
1D
1 Fig. 1A to Fig. 1C: Angiography image of a right coronary artery (RCA) and colored outline in three subsequent heartbeats, projected on top of each other (Fig. 1D), clearly showing that variations of the position of coronary arteries in each subsequent
1E
1F
1G
1H
1 Fig. E to Fig. G: Cross-section
of a coronary artery including
a calcified plaque with multisegment
reconstruction in three fused
projections. Small dimensioned
outlines can not be clearly depicted and information is lost in
the process (Fig. 1H).
55
Science
2. Changes in Heart Rate During the Scan
Variability in the position of the coronary
arteries from one cardiac cycle to the next
will be especially evident if heart rate
changes during the scan. Slight changes
in heart rate during image acquisition are
frequent. In slightly longer cardiac cycles,
2A
the diagnostic filling period is longer and
the heart will be more “expanded“ than
with faster heart rates. Thus, the end-diastolic position of the coronary arteries may
change and images reconstructed with
multi-segment algorithms will be an aver2B
age of several, non-identical cardiac cycles. With higher true temporal resolution
of CT scanners using half-scan (or singlesegment) reconstruction, heart rate variations are not a limitation and motionfree imaging becomes possible (Fig 2).
2C
2 Example of a patient in whom the rate of
normal sinus rhythm changes during the
scan. It drops from 75/min to 63/min during the initial phase of data acquisition
(Fig. 2A). Such changes in heart rate will
lead to differences in the position of the
coronary arteries from one cardiac cycle
to the next – a disadvantage for multisegment reconstruction. With half-scan
reconstruction and a temporal resolution
of 83 ms (SOMATOM Definition, Siemens
AG), clear and motion-free visualization
of the heart (right coronary artery) is
achieved in spite of the heart rate variation (Figs. 2B and 2C).
3. Arrhythmias During Data Acquisition
Not only can the heart rate change
during data acquisition (even if there is
sinus rhythm throughout), it also is possible – and, in fact, not infrequent – that
3A
arrhythmias occur in the form of supraventricular or ventricular ectopic beats.
Image quality of the single reconstructed
image remains unaffected in the case of
3B
3 78-year-old patient with previous bypass
surgery. Substantial supraventricular
arrhythmia occurred during the scan (Fig.
3A). Half-scan reconstruction with a temporal resolution of 83 ms remains unaffected from the arrhythmia and allows
precise delineation of bypass grafts and a
stenosis in the venous graft to the left anterior descending coronary artery (Fig. 3B,
arrow). Angiography confirms the finding
(Fig. 3C, arrow).
half-scan reconstruction because it is not
necessary to average data from several
heart beats (Fig. 3).
3C
Science
4. Reduced Pitch for
Multi-Segment Reconstruction
In order to be able to use data from several
cardiac cycles to reconstruct a cross-sectional image at any given z-axis position,
the x-ray detector has to cover that position during several consecutive cardiac cycles. The more cardiac cycles are to be
used for reconstruction, the slower the
movement of the patient relative to the
detector has to be. Thus, the pitch which is
defined as the table movement during a
360° rotation divided by the collimated detector width has to be chosen low and in
each given z-axis position, the patient will
be exposed to radiation several consecutive times. This leads to increased radiation
exposure compared to single-segment reconstruction approaches. In addition, since
the overall scan time will be longer, more
contrast agent must be given to the patient to ensure full enhancement of the
blood pool during the longer period of
data acquisition.
A further effect of this issue is that exclusion of ectopic beats from the reconstruction process may not be possible. Occasionally, ectopic beats will require
excluding one or several heart beats from
reconstruction in order to avoid misalignment artifacts. However, in that case, it
may occur that the z-axis position inquestion will not be covered by the detector
in enough “regular” heart beats to allow
multi-segment reconstruction (Fig 4).
4A
4B
4C
4D
4E
4F
5. Examples
Multi-segment reconstruction may theoretically lead to shorter data windows used
for image reconstruction (compensated for
by using data from several consecutive cardiac cycles), but it does not in all cases
lead to elimination of motion artifact or
improved image quality. In fact, Magnetic
Resonance coronary angiography uses extensive averaging of heart beats in their
data acquisition and reconstruction process, but even though the theoretical resolution of magnetic resonance coronary artery imaging is below 0.5 mm, images
never reach the crispness and sharpness
seen in cardiac CT. This is the consequence
of blurring which is caused by the averaging of usually eight to 16 cardiac cycles.
4 Exclusion of an ectopic beat to avoid artifact in 64-slice CT. In the ECG trace, gray bars
indicate the times during which data is used for image reconstruction (Fig. 4A). Because
of the ectopic beat, one of these data windows is in systole (arrow). This leads to artifacts which can be seen in the CT images at the level of the mid to distal right coronary
artery (arrows, Figs. 4A and 4C). After exclusion of the data acquired during the ectopic
beat from image reconstruction in Fig. 4D (marked in blue), the right coronary artery is
sharply delineated (arrows, Figs. 4E and 4F).
57
Science
5A
5A
57-year-old female.
Heart rate 68/min.
Half-scan reconstruction yields good image quality of the
right coronary artery.
Multi-segment reconstruction at the same
cardiac phase (40 %
of cardiac cycle)
shows obvious motion artifact of the
right coronary artery
(right, arrow).
5B
73-year-old male.
Heart rate 72/min.
Half-scan reconstruction (left) yields
good image quality
of the right coronary
artery. Multi-segment reconstruction
at the same cardiac
phase (70 % of cardiac cycle) shows obvious motion artifact of
the right coronary artery (right, arrow).
5B
In coronary CT angiography, multi-segment reconstruction does not reliably
lead to elimination of motion artifacts.
In fact, new artifacts may be introduced.
Two examples are shown here (Fig. 5).
Summary
Even though multi-segment reconstruction, as compared to half-scan reconstruction, offers nominally shorter data
windows during each cardiac cycle used
for image reconstruction, the fact that
data from several cardiac cycles need to
be combined to make up for the missing
projections constitutes a drawback that
may have negative influence on image
quality. “Blurring” may occur because the
coronary arteries do not return to exactly
the same position from one cardiac cycle
to the next. The reduced pitch may cause
higher radiation dose and may require a
larger amount of contrast agent. Irregularities of the heart rate and arrhythmias
may be more difficult to compensate for
than with half-scan reconstruction. Finally,
the initial experience with Dual Source CT
demonstrates that high, true-temporal
resolution in combination with half-scan
reconstruction allows reliable imaging of
the coronary arteries even with high
heart rates.
References
1 Budoff MJ, Achenbach S, Blumenthal RS, et al.;
Circulation 2006; 114(16): 1761–91.
2 Hendel RC, Patel MR, Kramer CM, et al.;
J. Am. Coll. Cardiol. 2006; 48(7): 1475– 97.
Education & Events
CT Life Card: Clinical Education at Your CT Workplace
There is an easy way to increase your skills
at the CT workplace: exclusively for the
SOMATOM® Definition, Siemens Medical
Solutions introduces the CT Life Card, a
portal for a wide spectrum of information
and services at your scanner. The CT Life
Card combines the Operator Manual,
LifeNet and the new Workflow Assistant
on one modern education and communication platform. The Workflow Assistant is
a state-of-the-art CT examination guide
that takes you from patient preparation,
through scan acquisition to data evaluation. It expands your clinical knowledge by
offering best practice examples including
clinical background, current indications
and fascinating case-studies. It provides
useful workflow tips that enhance the
confidence of the unexperienced user
when performing advanced CT procedures
such as cardiovascular imaging. It illustrates the quickest path to excellent clinical results using workflow movies that
demonstrate the clinical utility of CT appli-
CT Life Card – a portal to a wide spectrum
of information and services at your workplace.
cation tools such as syngo® Circulation
and others. The Workflow Assistant is also
available on DVD as a convenient tool for
general staff education. In addition, via
the LifeNet portal on the Life Card, you
will find current information on CT education and gain access to helpful services
such as ordering of trial licenses for the
latest clinical applications.
A workflow guide for cardiac imaging – how
to perform left ventricular functional evaluation
with syngo Circulation.
* The DVD will be provided to all customers working
with the software version syngo CT 2007C. For
additional copies, please contact your local Siemens
representatives
E-Logbook: Eliminate Cumbersome Paperwork
The E-Logbook* is a very handy tool that
automatically records necessary data to
be saved. You only have to enter specific
additional information when needed.
In many clinics, it is still common use to
note patient examination data in a socalled “paper logbook.” With the newly
developed E-Logbook you save time and
will be guaranteed an error-free reporting
compared to the conventional, handwritten patient logbook.
The E-logbook input fields are individually configurable to include what really
matters in the department. Parameters
that are already available within the
system (e.g. patient name, Patient ID,
dose values) will be transferred to the
E-Logbook automatically after completing
the examination. Other parameters can
then be typed in manually if desired. All
recorded examination data are saved to
a local database. Searching for a certain
patient examination on a certain date is
now only a matter of a few clicks. Additionally, the files can be transferred to
any PC, e.g. for statistical evaluations in
Microsoft Excel. A print-out of the data is
possible directly from the scanner. “With
the E-Logbook, we can quickly check
what examinations we have done over
the whole lifetime of our SOMATOM CT
system. The system records all parameters automatically, which saves us time
compared to a paper logbook”, says
Michaela Henkel, technician of the Radiological Institute at the Werner-Wicker
Klinik, Bad Wildungen, Germany.
* The E-Logbook option is now available for all
SOMATOM Sensation, Emotion and Spirit scanners
with the syngo CT 2007 software.
59
Education & Events
New: Cardiac CT Poster for
all Siemens Customers
Siemens Medical Solutions announces a new Cardiac CT Anatomy poster.
A special offer to all our customers: This high-gloss poster shows detailed CT
images of main cardiac structures including all coronary vessels, cardiac
valves, standard Myocardial Segmentation (AHA 17-Segment Model), different cardiac planes and standard views compared to conventional Angio
(size: 84 cm x 119 cm; 33,11 x 46,81 inches). The images were provided by
the University Hospital of Munich-Grosshadern (Department of Radiology
and Cardiology) and the University Hospital of Erlangen-Nuremberg in Germany and were acquired with the SOMATOM Sensation 64 slice scanner and
the SOMATOM Definition. Order your poster free of charge via this link:
www.siemens.com/
ct-cardiac-poster
New: CTA Interpretation Workshops
The Friedrich-Alexander University Hospital and Siemens Medical Solutions offer
clinical workshops specifically for image
evaluation.
Conducted by Stephan Achenbach, MD,
FESC, FACC, from the Friedrich-Alexander
University Hospital Erlangen-Nuremberg,
Germany, these courses focus on providing the participants with hands-on experience in the interpretation of coronary CT
angiography data sets.
For two days, participants have the opportunity to use image interpretation work-
stations and evaluate 50 original coronary CT angiography scans, which leads
towards Level II certification. These cases
range from easy, introductory to more
advanced cases with difficult diagnoses
and typical pitfalls.
Invasive coronary angiography correlation are available for every CT angiography case. Two participants work on one
workstation jointly, and a faculty is available to provide help and guidance. In
addition, two lectures are given during
the lunch breaks.The first course in March
2007 was very successful. “This is the
most interesting course I’ve ever participated in,” says Miclaus Gratian, MD, from
the Neuromed Center of Diagnostic Imaging in Timisoara, Rumania.
The course is most suited for Cardiologists and Radiologists with basic knowledge of cardiac CT.
Upcoming Dates:
19–20 July 2007 (Course ID: ERL5)
20–21 Sept. 2007 (Course ID: ERL6)
For online registration please go to the
following link and select: ‘Professional
Clinical Education’ and ‘Course schedule.’
Here you will also find information about
all upcoming courses for 2007. Educate,
stay up-to-date!
www.siemens.com/
somatomeducate
Exclusively during this clinical workshop: The participants could evaluate more than 50 datasets.
Education & Events
Free 90 Day Trial
Licenses* for
Clinical Applications
Try the following advanced clinical applications: syngo® Neuro DSA and syngo
Circulation 90 days for free! The clinically
proven syngo Neuro DSA CT provides an
easy, fast and fully automated method to
improve the detection of intracranial aneurysms and subsequent therapy planning**. It facilitates optimal visualization
and evaluation of complex intracranial
and extracranial vascular structures, especially at the base of the skull, and helps to
delineate aneurysms, stenoses, and other
vascular diseases.
syngo Circulation is your fast track to a
complete, noninvasive cardiac evaluation
in less than ten minutes. The intelligently
designed, guided workflow will lead you
effortlessly to a confident diagnosis, from
quantitative coronary assessment and
plaque analysis to left ventricular and
myocardial analysis, ultimately fusing all
your diagnostic findings into a single
comprehensive report. For details regarding trial licenses, please consult your
Siemens representative.
* Minimum system requirements need to be fulfilled
for these options to be available. Ask your Siemens
representative to check your system configuration.
** Tomandl et al. AJNR 2006, 27: 55–59.
Frequently Asked Questions
How to turn mAs/ rot at the SOMATOM Definition into
effective mAs?
Please use the following formula: mAs/ rotation = 2 x mA x rotation
time. When placing the mouse cursor over the mAs setting in the
routine subtask card, you can see the corresponding value from the
SOMATOM® Sensation 64-slice configuration. Further information
can be found in the online help (F1 key).
How can I display the cardiac phase information
in the Browser?
To display the cardiac phase, please open the Browser and deselect under Viewing the entry Image Stamps. Select Options –
Configure Browser – Tree View – Instance. There you will find
under Data Type CT Image. Select the entry Image Comment
and add this via a click on the down arrow to Heading Settings.
61
Education & Events
E-Newsletter
The CT monthly e-newsletter from
Siemens Medical Solutions includes highlights on clinical outcomes, business,
science and customer care topics. As
subscriber, you will receive latest information on upcoming Siemens CT events
and courses. Answers to frequently asked
questions will be given, along with a section with tricks and tips on “how to …”
efficiently use Siemens CT scanners and
applications in daily clinical practice.
Stay up-to-date with what is happening
in the world of computed tomography
with the Siemens Medical CT Newsletter.
Subscribe via the following link, or with
the postcard attached to the back cover
of this magazine.
www.siemens.com/
medicalnews
Latest information with the monthly CT e-newsletter.
Upcoming Events & Courses
Title
Location
Short Description
Date
Contact
ESC
Vienna, Austria
European Society of
Cardiology Congress 2007
Sep. 1–5, 2007
www.escardio.org
9th Biennial
ESTRO Meeting
Barcelona, Spain
European Society for
Therapeutic Radiology
and Oncology
Sep. 8–13, 2007
www.estroweb.org
ESNR
Genova, Italy
European Society of
Neuroradiology Congress
Sep. 20–23, 2007
www.esnr.org
ESCR
Rome, Italy
Annual Scientific Meeting
Oct. 18–20, 2007
www.escr.org
JFR
Paris, France
Société Française
de Radiologie Congrès
Oct. 20 –24, 2007
www.sfrnet.org
TCT
Washington, USA
Transcatheter Cardiovascular
Therapeutics Symposium
Oct. 20–25, 2007
www.tct2007.com
AHA
Orlando, USA
American Heart Association
Scientific Sessions
Nov. 3–7, 2007
www.scientificsessions.org
Medica
Duesseldorf, Germany
MEDICA 2006
Nov. 14–17, 2007
www.medica.de
RSNA
Chicago, USA
Radiological Society of
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Nov. 25–30, 2007
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Moscow
Healthcare
Moscow, Russia
Dec. 5–9, 2007
17th international Exhibition
of Health Care, Medical
Engineering and Pharmaceutics
www-eng.expocentr.ru
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© 2007 by Siemens AG, Berlin and Munich, All rights reserved
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Chief Editors
Monika Demuth, PhD
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Stefan Wünsch, PhD
([email protected])
A. Davis, MD, Hartsdale Imaging, Hartsdale,
New York, USA
A. Graser, MD, Department of Clinical Radiology,
University Hospital of Munich-Grosshadern, Munich,
Germany
A. Hirayama, MD, Cardiovascular Division,
Osaka Police Hospital, Osaka, Japan
T. Johnson, MD, Department of Clinical Radiology ,
Germany
K. Kodama, MD, Cardiovascular Division, Osaka Police
Hospital, Osaka, Japan
Editorial Board
Nina Bastian
Thomas Flohr, PhD
Murat Guengoer
Louise McKenna, PhD
Julia Kern-Stoll
Axel Lorz
Jens Scharnagl
Bernhard Schmidt, PhD
Heiko Tuttas
Alexander Zimmermann
S. Komatsu, MD, Department of Internal Medicine 2,
University of Erlangen-Nuremberg, Erlangen, Germany
and Cardiovascular Division, Osaka Police Hospital,
Osaka, Japan
Authors of this Issue
S. Achenbach, MD, Department of Internal Medicine
2, University of Erlangen-Nuremberg, Erlangen, Germany
A. Megibow, MD, MPH, FACR, Department of Radiology, NYU Medical Center, New York, USA
K. Anders, MD, Institute of Diagnostic Radiology,
A. Aplas, MD, Department of Radiology University
of Erlangen-Nuremberg, Erlangen, Germany
W. Bautz, MD, Institute of Diagnostic Radiology, University of Erlangen-Nuremberg, Erlangen, Germany
C. Becker, MD, Department of Clinical Radiology,
Germany
A. Küttner, MD, Institute of Diagnostic Radiology,
A. Kuhlmann, MD, Department of Internal Medicine 2,
A. Mahnken, MD, Department of Diagnostic Radiology, RWTH Aachen University, Aachen, Germany
N. Mollet, MD, PhD, Departments of Radiology and
Cardiology, Erasmus, Medical Center, Rotterdam, the
Netherlands
T. Pflederer, MD, Department of Internal Medicine 2,
D. Ropers, MD, Department of Internal Medicine 2,
U. Ropers, MD, Department of Internal Medicine 2,
P. Seidensticker, MD, Global Medical Affairs Diagnostic
Imaging, Bayer Schering Pharma AG, Berlin, Germany
S.-H. Chu, MD, Cardiovascular Center, Far Eastern
Memorial Hospital, Taipei, Taiwan
J. Vlahos, MD, Department of Radiology, NYU Medical
Center, New York, USA
W. Daniel, MD, Department of Internal Medicine 2,
M. Wechsel, MD, Department of Internal Medicine 2,
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The statements and views of the authors in the individual contributions do not necessarily reflect
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A. Weustink, MD, Departments of Radiology and
Cardiology, Erasmus Medical Center, Rotterdam, the
Netherlands
J. Wildberger, MD, Department of Diagnostic Radiology, RWTH Aachen University, Aachen, Germany
Catherine Carrington, freelance author
Tim Friend, freelance author
Robert Harsieber, PhD, freelance author
Frank Miltner, freelance author
David J. Tenenbaum, freelance author
Tony DeLisa, freelance author
Karin Barthel; Nina Bastian; Dagmar Birk; Andreas
Blaha; Wai Leng Chin; Jan Chudzik; Monika Demuth,
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