1. Peripheral Vascular MR Angiography
Indications
Equipment
Technique
Image Analysis
Example Cases
Reporting - Billing

2. Thank You Yi Wang, PhD Qian Dong, MD Richard Watts, PhD Jim Meaney, MD
Priscilla Winchester, MD Vince Ho, MD
Neil Khilnani, MD Tom Chenevert, PhD
David Trost, MD
Craig Kent, MD
Bernie Redd, MD

3. Indications: Intermittent Claudication Non-healing ulcer
Post bypass graft
Aneurysm
Pre free-flap
Pediatric

4. Indications for MRA Difficult access Renal insufficiency Cr > 2.0
Allergy to iodinated contrast
Patient refuses conventional angiography

5. Advantages of MRA No nephrotoxicity Allergic reactions rare 3D
Anatomy and Physiology
High Accuracy
Affordable (reimbursement = $1159)

6. Advantages of Gadolinium
No pulsatility artifact
No slice misregistration
No in-plane saturation
High resolution (1.8 x 1.6 x 2.6 mm)
Fast

7. Equipment for Peripheral MRA
Magnet:
1.5 Tesla  high SNR
0.5 Tesla  requires more Gd
High performance gradients
Coil: body and head coil
Injector vs hand injection
Foam and straps

8. Table Positioning Pole
PVC tubing
2 inch diameter
3-4 meters long
holes at 36 or 40 cm spacings

9. Table Positioning Blocks

10. Technique: younger vs older
Young Adult
Older patient
2D TOF Tech (30 years old)
2D TOF Radiologist (41 years old)
2D TOF: 1 hour
3D Gd MRA: 87 seconds 3

11. Technique Pediatric – Young Adult (fast flow)
Head or extermity coil
2D time-of-flight
Gd almost never necessary
Gating +/-
Older Patients (slow flow)
Head coil
2D projection MRA of ankle-feet
Body coil
3D Bolus chase MRA: Renals  distal calf
3D phase contrast of renal arteries

12. 3 Critical Details Positioning Bolus timing Subtraction Unsubtracted5

13. Bolus Chase MRA Technique
2D Projection MRA (timing): 1 min
Floating Table min
Sag Loc min
Axial Loc min
Cor 3D-Gd-MRA
Pre min
During min
3D phase contrast (renals) 7 min
Total Imaging Time min
Total Exam Time <1 hr 7

14. 2D Projection MRA: ankle-feet
Raw image
Complex subtraction
Left
Right
Coronal T1

15. 2D Projection MRA: + complex subtraction
Ankles
Knee 9

16. 2D Projection MRA (Left foot)
20.3 sec
24.4 sec
28.4 sec
32.5 sec
72.7 sec
Time to fill distal station = 24 seconds
Time to fill pelvis = 2/3 (24 sec) = 16 sec
Time for venous contamination = 60 sec

17. Calculation of Bolus-Chase Injection Timing Parameters
Time to venous contamination = 60 seconds
Time to fill pelvis = 16 seconds
Centers of k-space
scan delay 6
Station 1 = pelvis 6
Station 2 = thigh 6
Station 3 = calf 10 30 45 65 8

18. Bolus Chase MRA Preparations
level legs
secure feet with curlex
determine length of stations
landmark above umbilicus 11

19. Overlap Common Femoral Bifurcation
Position for Overlap at Critical Sites
Overlap Trifurcation
Overlap Common Femoral Bifurcation

20. Bolus Chase Positioning
2D TOF
P 60
P 20
P 45
A 25
A 30
Internal iliac
Ankle
Popliteal
Common femoral

21. Selecting Imaging Parameters
Slice thickness = 3 (2-5) mm
# of slices = 28 (20-40)
Frequency = 256
Phase = 160 ( )
Phase FOV = 0.8 (1-0.6)
Bandwidth = 31 (31 or 62)

22. 3D Gadolinium Bolus Chase MRA
Breathhold 1st station
Use oxygen liberally
Scan delay ~ 10 sec 15

23. Image Post Processing Digital subtraction: pre from post
Complex Fourier Subtraction
Do not subtract MIPs
MIP subtracted source images
Reformat into lateral & oblique projections
Subvolume MIPs for selected regions
renal arteries
mesenteric arteries
common femoral bifurcations
regions of greatest interest
Examine pulsatility artifact on 2D TOF images 16

24. Oblique views obtained by reformatting data on computer even after patient leaves
Oblique MIP
Coronal MIP

25. Popliteal Artery Aneurysm
Male>>> female
Risk of complications
thrombosis => high
emboli => high
rupture => low
Associated with other aneurysms

26. Patient could not straighter knee
2D Projection MRA

27. Peripheral Vascular MRA
Year # Patients Technique Sensitivity Specificity
Owen (NEJM) D TOF superior to DSA
Baum (JAMA) D TOF 82 84
Prince (Radiology) D Gd 94 98
Snidow (Radiology) D Gd
Hany (Radiology) D Gd
Ho (Radiology) Bolus chase 93 98
Meaney (Radiology) Bolus Chase
Yamashita (JMRI) D Gd 96 83
Lee (Radiology) D Gd 94 91
Winchester (JMRI) D Gd 90 98
Link (Radiology) D Gd
(post stent)

28. Reporting

32. Useful Descriptors Descriptor Meaning Occluded
Severe stenosis > 75% narrowing
Moderate stenosis %
Mild stenosis < 50% narrowing
Normal normal
Widely patent wide open: +/- tortuosity
+/- atherosclerotic irregularity
Ectatic  diameter < 50% more than normal
Aneurysmal  diameter > 50% over normal

33. Useless Descriptors Descriptor Meaning
Stenotic “I think there is a stenosis”
Patent “I see the artery”

34. MRA Summary No Ionizing Radiation No Contrast Injection necessary
If Contrast  No nephrotoxicity
Reformat to obtain an view
Anatomy and Physiology
High Accuracy
Tremendous Future