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Abdominal CT Perfusion: Effects of Breath Control
Technique
Poster No.:
C-0068
Congress:
ECR 2014
Type:
Scientific Exhibit
Authors:
T. Yoshikawa , T. Kanda , Y. Ohno , Y. Fujisawa , N. Negi , M.
1
1
2
1
1
1
3
1 1
1
2
Nishio , H. Koyama , K. Sofue , K. Sugimura ; Kobe/JP, Tokyo/
3
JP, Otawara-Shi/JP
Keywords:
Hemodynamics / Flow dynamics, Technology assessment,
Contrast agent-intravenous, Computer Applications-3D, CTQuantitative, Spleen, Pancreas, Liver
DOI:
10.1594/ecr2014/C-0068
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Aims and objectives
BACKGROUND
CT Perfusion (CTP) is reportedly useful for evaluation of liver damage or severity of
hepatic fibrosis associated with chronic liver disease, prediction of tumor response to
therapies, and evaluation of hepatic perfusion changes after surgical or radiological
interventions.
This method is also reportedly useful for evaluation of various diseases and conditions
in other upper abdominal organs, such as pancreas, spleen, and stomach.
However, some problems still remain with using this method. One of them is need for
relatively long breathholding. Moreover, respiration-related motion artifacts also pose a
significant problem.
In some previous reports, abdominal CTP was performed under breathing without
assessment of validity.
Assessments for these issues are essential for effective routine clinical use of this
technique.
PURPOSE
To assess effects of breath control technique on CT perfusion values in the abdomen
Methods and materials
Patients
115 patients, who were highly suspected to have intrathoracic malignancies, (male: 69,
female: 39, mean age: 70.6 years old) underwent upper abdominal routine CT and CTP
for preoperative assessment. All subjects gave their informed consent.
4 patients who had metastatic liver tumors were excluded from the study population
because this study was aimed to assess subjects without pathological condition in the
abdominal organs.
3 patients were excluded because a 20-gauge catheter could not be placed properly in
the peripheral vein.
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The remaining 108 patients, who did not have any indications of pathologic conditions in
the upper abdomen constituted the study population and were randomly divided into two
groups; breathholding group and free breathing group.
Demographic features and scan parameters (FOV, CTDI, and DLP) for CT perfusion
were recorded and compared.
Imaging Techniques
A 320 detector-row CT (Aquilion ONE, Toshiba Medical Systems, max. cranio-caudal
coverage:16cm) was used.
Dynamic scans were conducted 7 to 120 secs after injection of contrast medium (CM)
under breathholdings or free breathing (fig. 1).
The center of the scan volume was set at hepatic hilum.
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Scanning conditions: 80kV, 210mA
Reconstruction: 0.5 mm thk x 320 slices
Injection dose and rate of CM: 30ml, 5ml/sec
Saline chaser: 25ml, 5ml/sec
Pre- and post-contrast abdomino-pelvic scans were also acquired with additional contrast
medium injection of 70ml.
Misregistration Compensation & Compensation Length
The CT images were then transferred to a prototype workstation (Toshiba Medical
Systems), and prototype software was used for analysis.
Respiratory misregistrations were compensated for first manually and then automatically
with the software before perfusion analysis (fig. 2).
Maximum length of manual compensation (mm) (usually z-direction) was recorded for
each patient and compared between the groups (figs. 3-6).
Perfusion Analysis
Hepatic arterial and portal perfusion (HAP and HPP, ml/min/100ml), arterial perfusion
fraction (APF, %), mean transit time (MTT, s), and distribution volume (DV, ml/100ml)
were calculated using dual-input maximum slope (dMS), deconvolution (dDC), and
compartment model (dCM) methods using the same ROIs.
Arterial perfusions (AP), MTT, and DV of pancreas, spleen, gastric wall were also
calculated using single-input MS, DC, and CM (sMS, sDC, sCM) methods.
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Oval ROIs for perfusion measurement were placed by two experienced radiologists, who
made a consensus opinion, on the right liver and spleen at the level of the splenic hilum
and on pancreatic body and gastric fundus on the perfusion maps and made as large as
possible while avoiding large vessels and ducts.
The values were compared between the groups.
Images for this section:
Fig. 1
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Fig. 2
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Fig. 3
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Fig. 4
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Fig. 5
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Fig. 6
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Results
There was no significant difference in demographic features or scan parameters (fig. 7).
Mean manual compensation length had a trend toward larger in free breathing group
(13.5 ± 7.7) than breathhold (11.3 ± 7.9) (fig. 7).
HAP with dCM (p<0.05) and HPPs with dMS, dDC (p<0.05), and dCM (<0.005) were
significantly lower in breathhold group (fig. 8).
MTTs in the liver with dDC (<0.0001) and dCM (<0.0005) were significantly higher in
breathhold group (fig. 8).
There was no significant difference in pancreatic, splenic, or gastric perfusion values
(figs. 9-11).
Images for this section:
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Fig. 7
Fig. 8
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Fig. 9
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Fig. 10
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Fig. 11
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Conclusion
DISCUSSION
Our results show that even after careful compensations for respiratory misregistrations,
CT perfusion values in the liver are affected by breath control technique.
Changes in portal perfusion values were possibly due to structure distortions, which made
vessel tracking process in analysis difficult.
CM transit time changes might be caused by intra-thoracic or inferior vena caval pressure
changes.
The effects of breath control technique are similar among the commonly-used three
analytic methods.
These changes in perfusion values should be considered in clinical use, and breath
control technique should be the same throughout serial examinations.
LIMITATIONS
Our sample size was relatively small which restricts statistical significance, so that further
studies with a larger population are needed to verify our results.
We only evaluated patients without abdominal diseases. Liver stiffness can increase in
proportion to severity of chronic diffuse diseases. Motion-related motion may be different
between normal liver and cirrhotic one. Perfusion measurements of focal diseases such
as tumors can be more affected by respiration-related motions because they are smaller
in size. Further studies limited to one specific disease or condition are needed.
Even with a 320-detector row CT, the cranio-caudal scanning range is limited to 16 cm,
which means that the entire liver of a significant proportion of our subjects could not be
covered and this may have also affected our results.
CONCLUSION
Even after careful compensations for respiratory misregistrations, CT perfusion values in
the liver are affected by breath control technique.
When measuring hepatic portal perfusion or contrast medium transit time, breathhold
technique is recommended.
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Personal information
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