Presented by Wong Ka Kui Rad II, QEH

Presented by Wong Ka Kui
Rad II, QEH
Definition and Cause of PVD
Peripheral Vascular Disease (PVD)
- Disease of blood vessels outside heart and brain
- Mostly obstruction of large arteries like arms or legs
- Result from atherosclerosis, thrombus formation or
inflammatory processes leading to stenosis
Modalities for diagnosis PVD
1. DSA
2. CT
3. US
4. MRI
DSA for PVD
Advantages :
1. high resolution image
2. diagnosis and therapeutic approach
Shortcomings :
1. invasive
2. nephrotoxic iodine-based contrast
3. high radiation dosage
4. 2D images only, eccentric stenosis of a tortuous
vessel may be underestimated
5. little information about vessel wall morphology
CT for PVD
1.
2.
3.
4.
Advantages :
non-invasive
high spatial resolution
short acquisition time
provide information about extraluminal structure,
wall status (e.g., calcifications / plaques)
Shortcomings :
1. high radiation dosage
2. nephrotoxic iodine-based contrast
3. time consuming in post processing
4. beam-hardening artifacts in severely calcified
vessels
US for PVD
Advantages :
1. no radiation
2. non-contrast
3. non-invasive
4. Doppler US can provide blood flow information
Shortcomings :
1. operator dependent
2. limited penetration
3. low-resolution image
4. time consuming in multiple lesion patients
5. no comprehensive overview of the vascular system
MRI for PVD
Advantages :
1. no radiation
2. non-invasive
3. low toxicity contrast
4. short acquisition time
5. reconstructed MPR and MIP
6. provide 4D images - temporal resolution
Shortcomings :
1. patients have pacemakers, aneurysm clips or
claustrophobia cannot receive MRA
2. overestimated of stenosis
3. no bony landmarks
Methods of MRA
Routine used Non Contrast MRA techniques
1. Time of Flight (TOF)
2. Phase-Contrast (PC)
Contrast-enhanced CeMRA
1. Acquired 3D image by TimCT
2. Acquired 4D image by TWIST
New developed Non Contrast-Enhanced MRA
1. NATIVE TrueFISP
2. NATIVE SPACE
TimCT CeMRA
Continuous Table Move Powered by Total
imaging matrix (TimCT)
- is a new technology to scan a large
anatomical coverage beyond the scanners
intrinsic FOV
- scan and move at the same time
- start from renal arteries to the feet
Blasche, 2006
TimCT CeMRA
Advantages :
1. Reducing planning steps
2. Shorten the examination time
- no scanning pauses for the table moves which velocity is
5cm/sec
- most images reconstruction are automatically generated
3. Improve image quality
- higher spatial resolution as tracking contrast bolus
- less boundary artifacts
- scan at isocenter
- avoid noise sampling
Blasche, 2006
TimCT for peripheral CeMRA
Required coil coverage – 24-channel spine matrix
coil, two 6-element body matrix coils and 8-element
peripheral coil ( Quick & Barkhausen, 2006).
TimCT for peripheral CeMRA
Quick & Barkhausen, 2006
TimCT for peripheral CeMRA
Quick & Barkhausen, 2006
TimCT for peripheral CeMRA
Quick & Barkhausen, 2006
TimCT for peripheral CeMRA
Significant stenosis at left common iliac artery
Significant stenosis at left surperficial femoral artery
Quick & Barkhausen, 2006
TWIST CeMRA
Time-resolved angiography with interleaved stochastic
trajectories (TWIST)
- is a new k-space coverage technique during data
acquisition in combination used with iPAT to perform subsecond time-sequential 3D acquisition to generate 4DMRA (Laub & Kroeker, 2006).
Advantages :
- high temporal resolution about 1 to 5 seconds
- low dosage of contrast
- without bolus-timing
Shortcomings :
- not enough spatial resolution
NATIVE TrueFISP and NATIVE
SPACE
Advantage :
- contrast is not required
- suitable for geriatric and renal disease patient,
Creatinine level F-370; Male-480, lower the risk of
Nephrogenic Systemic Fibrosis (NSF)
Special Characteristic :
- require ECG trigger
- use TrueFISP characteristic to depict the vessels
NATIVE TrueFISP – optimized for
renal arteries
Based on
- 180 ° inversion pulse invert the ROI
- imaging takes place after inversion time (TI)
- the flash inflow flowing blood is not inverted
(Rick et al., 2009)
NATIVE TrueFISP MIP reconstruction image
Right renal artery
Left renal artery
(Rick et al., 2009)
NATIVE SPACE – optimized for peripheral regions
Based on
- the difference in the signal-intensity between slow-flowing blood
(diastole) and fast-flowing blood (systole)
- use cine and Mean curve to measure the trigger delay between two
acquisitions
- two images are subtracted to removes background and
venous signals
(Rick et al., 2009)
NATIVE SPACE images
Peak
Flow
image
Subtraction image
Min Flow
image
Inline MIP
Coronal MIP of a multistep protocol
(Rick et al., 2009)
4 Case studies
1. Hybrid CeMRA techniques for peripheral
vessels
2. Hybrid CeMRA techniques for vessels of
aortic arch
3. CeMRA and NATIVE TrueFISP for Renal
artery stenosis
4. CeMRA and NATIVE SPACE for
peripheral vessels
Hybrid techniques for peripheral
vessels
Patient history
- F/72
- HT, DM, IHD, peripheral vascular disease
with ulcers over both lower limb
- Request for MRA of pelvic and lower limb
vessels
Protocol
- TimCT peripheral CeMRA and TWIST
lower leg CeMRA
TimCT CeMRA contrast injection rate
1. 21ml saline at 1.5ml/sec
2. 10ml contrast at 1.5ml/sec
3. 10ml contrast at 0.8ml/sec
TWIST CeMRA
1. no need for Test bolus
2. 10 ml contrast at 1.5ml/sec
3. 30 dynamic measurements with 4 sec
temporal resolution
Hybrid techniques for peripheral
vessels
Diagnosis of this patient
- Most artery are patent
- Left SFA and left popliteal artery have
multiple short segments of moderate
narrowing
- Doppler US is suggested to rule out
Deep Vein Thrombosis (DVT)
Hybrid techniques for vessels of
aortic arch
Patient history
- F/60
- Great discrepancy in BP reading on both arms, Rt is
much lower than Lt arm
- P/E absent Rt brachial pulse and decrease volume of Rt
radial pulse
- Result of US Carotid Doppler showed no significant
stenosis in noted extracranial carotid arteries
- Request of MRA of great vessels of aortic arch
Protocol
- Routine CeMRA and TWIST CeMRA of aortic arch’s
vessels
1st pass MIP images of vessels of
aortic arch
TWIST CeMRA images of vessels
of aortic arch
Hybrid techniques for vessels of
aortic arch
Diagnosis of this patient
- Complete obliteration of right subclavian
artery at level about origin of thyrocervical
trunk, distal right subclavian reconstructed
by collaterals
- Other artery is normal, right carotid and
vertebral artery are normal
Renal artery stenosis
Patient History
- F/60
- Renal transplant on 1996, deteriorating
renal function, Serum Creatinine -148
- Doppler US showed significant renal artery
stenosis
- Request of CeMRA for further delineation
Protocol
- Routine CeMRA compared with Native
TrueFISP
MIP images of NATIVE TrueFISP
and CeMRA
NATIVE TrueFISP
Routine CeMRA
Diagnosis – main renal artery significant artery stenosis has to be considered
Comparison of CeMRA to NATIVE
SPACE for peripheral vessels
Patient History
- M/70, HT, DM, hyperlipid, old MI, IHD
- impaired RFT, Serum Creatinine - 216
- P/E both sides dorsalis pulses are reduced, PVD
is considered
- Request for CeMRA of peripheral vessels
Protocol
- TimCT CeMRA compared to TimCT NATIVE
SPACE for peripheral vessels
MIP images of CeMRA and NATIVE
SPACE
TimCT CeMRA
NATIVE SPACE
Comparison of CeMRA to NATIVE
SPACE for peripheral vessels
Diagnosis
- Atherosclerotic changes noted along abdominal
aorta
- left distal anterior tibial artery is well opacified
Conclusion
The renal function of geriatric patient is always
deteriorating so contrast CeMRA is more suitable for
them to diagnosis PVD as the toxicity of MRI
contrast is lower than CT and DSA iodined-based
contrast. Besides, NATIVE TrueFISP and NATIVE
SPACE are new tecnniques developed for noncontrast CeMRA that is good for patient whose blood
Creatinine level is higher than 370/F and 380/M.
References
Blasche, M. (2006). syngo TimCT- Continuous Table
Move, Powered by Tim. Magnetom Flash, 3, 2-9.
Laub, G. & Kroeker, R. (2006). Syngo TWIST for
Dynamic
Time-Resolved
MR
Angiography,
MAGNETOM Flash, 3, 92-95.
Quick, H. H. & Barkhausen, J. (2006). MRI on the
Move : syngo TimCT. Magnetom Flash, 3, 15-22.
Rick, M., Kaarmann, N., Weale, P. & Schmitt, P.
(2009). How I do it: Non Contrast-Enhanced MR
Angiography (syngo NATIVE), MAGNETOM Flash,
3, 18-23.