1. Michael Wholey, MD, MBA San Antonio, Texas
CTA,MRA Vascular Diagnosis: Important Basic Facts with Aortoiliac and Lower Extremities
CRT 2011 Washington DC
CTA,MRA Vascular Diagnosis: Important Basic Facts with Aortoiliac and Lower Extremities
Michael Wholey, MD, MBA
San Antonio, Texas
Michael Wholey, MD, MBA
San Antonio, Texas

2. CTA,MRA Vascular Diagnosis: Important Basic Facts
No Financial Responsibilities
I wish I had some to report.

3. CTA Patient Preparation
Sedation
Labs
Creatinine
IV Access
18-20 Gauge access into antecubital fossa
Cardiac Meds
(if coronary CTA done conjointly)

4. Contrast Administration for CTA
For most CTA applications, we administer 100 of iohexol 350 mgI/mL (Omnipaque,) or iodixanol 320 mgI/mL(Visipaque), typically injecting at 4 mL/sec. In many cases, particularly peripheral runoff studies, we use a saline push.
Repeat CT (no contrast) scan beginning at knees

5. MIP (Maximum Intensity Projection) Volume Rendering
The set of tubes simulates vessels in a volume. With a MIP, all the vessels are visible, but their relationships to one another are not clear, as they are in the volume rendering.

6. Advances in MRA: Using Image Subtraction
Courtesy Univ Wisconsin Dept Radiology

7. MRA in runoff vessels 2D TOF method with extremity coil
ACR Rapid technology assessment
Baum et al JAMA 1995; 274:875
Multicenter trial (n=155 pts)
MRA distinguishes patent segments
Sensitivity MRA 85% DSA 83%
Specificity MRA 81% DSA 81%
MRA changed treatment plans 13%
Courtesy Univ Wisconsin Dept Radiology

8. Which to Chose CTA vs MRA?
Able to scan larger segments
Easier to schedule
Able to see surrounding pathology
Artifacts from calcium
No measure of flow
MRA
No Radiation
Less Nephrotoxicity
Requires several segments
More expensive
Flow artifacts
Contraindicated in pacemaker, implants

9. Try to order an MRI on a Patient with elevated creatinine ?
FDA describes the risk for NSF following exposure to a GBCA in patients with acute or chronic severe renal insufficiency (glomerular filtration rate <30 mL/min/1.73 square meters) and patients with acute renal insufficiency of any severity due to the hepato-renal syndrome

10. Pitfalls of CTA
A major pitfall is that although imaging vessel calcification is an advantage of CT, beam hardening artifacts remain difficulties, especially dense medial calcifications found in diabetic patients.
What is the degree of stenosis: 60% 70% 80% 90%

11. Benefits of CTA/MRA Assessment of Incidental Findings
Incidental Renal Cell Carcinoma found on routine CTA Abdomen in two pts

12. Benefits of CTA/MRA Assessment of Incidental Findings
Awareness of significant vascular findings
Pre-planning for intervention
Major decisions in patient management

13. Aortic CTA

14. Aortic Occlusion
What would you do with this renal artery ?
Aorta occluded just inferior to left renal artery which has high grade stenosis.

15. Abdominal Aortic Aneurysms
Diagnosis of AAA
Planning for stent management
 Sent for Open Surgery

16. Renal CTA/MRA

17. Comparison of Ultrasound, CTA and Gd Enhanced MRA for RAS
Test
Sensitivity
Specificity
Positive Predictive Value
Negative Predictive Value
Doppler U/S
75%
90%
60%
95%
CTA
94%
93%
71%
99%
MRA
98%
N=132 renal arteries compared with DSA
Rountas Ren Fail. 2007;29(3):

18. Renal MRA
Renal/abdominal MRA can detect renal artery stenoses with 94% sensitivity and 92% specificity
-MRA may miss stenoses caused by fibromuscular dysplasia, which have a characteristic beaded appearance in CTA or angiograms.
-if an accessory artery is very small, there is a risk that it may be missed by MRA.
-May miss distal disease
A bolus of gadolinium contrast agent is administered intravenously and images are acquired in a series of four to six 20 second breath-holds

19. Renal stenosis What do we learn: Plaque Morphology Lesion Length
Calcification, Soft Tissue
Lesion Length
Vessel Diameter
Vessel Location and Angle

20. Renal CTA: Use in Renal Stenting
s/p 5.5 x 15 BMS

21. Lesion Pathology: FMD Renal Stenosis
Allowed for treatment PTA plans

22. Distal Renal Disease How Common is it?
Calcified plaque in main and in segmental branches

23. Lower Extremity

24. MRA Lower Extremities Benefits of MRA :
-Easy to read with little manipulation
-drawback (soft tissues not well seen)
-Occluded Left SFA
-Diseased Bilateral Post Tibials

25. Lower Extremity: Epidemic

26. Again, do not forget incidentals
Arteriovenous fistula probably from heart cath, by a cardiologist…not a radiologist.

27. Information obtained from CTA
Pt with pulsatile mass behind knee
-Embolization performed afterwards
Pt with large mass left groin and hx fem-fem graft
-Large pseudoaneurysm

28. Interesting Below the Knee Case
HISTORY:
68 year old female with hx of CAD, PVD with non healing foot ulcer. Long Hx DM.
Abnormal LE Doppler with diseased infrapopliteal
CTA: Severe disease of the popliteal and proximal anterior tibial and occluded tibial peroneal trunk
3-D MPR

29. Angiogram Left Leg
Popliteal Artery
Anterior Tibial

30. Intervention
Laser
PTA 3 x 120 mm
Final
Cross with 0.014” Wire

31. CTA Lower Extremities
History:
-Patient with SFA stent placed one year ago.
-Patient returning with increased claudication of the right leg. Arterial Segmental pressures with decreased waveform right leg.
Intervention:
-Findings: in-stent restenosis of the stent
-Treatment: plan on PTA or removing plaque.

32. Benefits of Infrapopliteal CTA
CTA Shows moderate peroneal disease but severe anterior tibial
Based upon CTA findings , able to see anterior tibial, cross and PTA the vessel

33. Conclusions
Future is very bright for CTA/MRA