1. CTA or MRA for PVD Screening: Advantages and Limitations of Both
Michael H. Wholey, MD, MBA
Interventional Radiology
Christus Santa Rosa
San Antonio, TX
Monday Feb 6, :10-8:20 AM

2. Michael H. Wholey, MD Consulting Fees: Covidien
My presentation will include off-label discussions:
Carotid stents and embolic protection are off-label.

3. CTA or MRA for PVD Screening: Advantages and Limitations
Financial Responsibilities
Consultant:
Covidien
Boston Scientific
Founder:
Wholey and Wholey, LLC

4. Peripheral Vascular Disease:
Screening Tests
Non-Invasive Diagnostic Tests
Ankle Brachial Index (ABI)
Arterial Color Doppler (Duplex) Ultrasound
Arterial Segmental Pressures
Arterial Pressure Volumes (PVR)
CTA
MRA
Angiography
The Judgment of Paris, Peter Paul Rubens,

5. Lower Extremity: Epidemic

6. Symptoms of PAD Critical Limb Ischemia Asymptomatic Claudication
Acute Limb Ischemia
Amputation
-Rest Pain
-Tissue Loss
---Ulceration
---Gangrene

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

8. CTA or MRA Scan Lower Extremities
Should be used as a screen for patients with abnormal ABI, Segmental Pressures and/or Physical Exam.

9. Another View for Lower Extremity Intervention F/U:
Patients presenting with CLAUDICATION
American College of Radiology ACR Appropriateness Criteria®

10. MRA for PAD Benefits: No Radiation Less Nephrotoxicity
Easy to read and manipulate images
Do not have problems caused with calcium artifacts

11. MRA Lower Extremities: Bolus Chasing
Bolus-chasing method material in which vessels are imaged sequentially as contrast flows distally. Multiple overlapping fields of view are used, and images are obtained in the coronal or sagital planes (usually in 3 coronal stations). This technique also uses subtraction to improve the resultant vascular images by suppressing the background and reducing the volume averaging.
-Occluded Left SFA
-Diseased Bilateral Post Tibials

12. MRA Bolus Chasing Bolus-chasing MRA is rapidly evolving
Technology revolution that made equipment widely available,
Improvements in technical capabilities (eg, increased field strengths, dedicated coils, increased SNRs, decreased repetition times, improved bolus-detection techniques, MR SmartPrep technique)

13. MRA vs DSA 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%

14. MRA for PAD: Disadvantages
-Contraindications:
Implanted pacemakers
Defibrillators
Surgical aneurysm clips
Renal Dysfunction
-Difficulties in Interpretation
MRA also takes longer to perform than a CT angiogram
More Expensive
Requires multiple segments
Difficulties in Performing
Limited on visualization of small vessels
Overestimation of stenosis
Metal stents
Disrupt the MRA images.

15. 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

16. CTA: Ability to see whole body
Guidewire exited the right common iliac and caused Type B Dissection

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

18. CTA: Pelvic Pathology Persistent Femoral Sciatic Artery
-35 yr old pt s/p PTCA with claudication
-Allows quick overview of multiple diseased segments
-Allows for intervention planning

19. CTA: Femoral Disease
Closure device complication in diseased cfa

20. 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.

21. 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

22. 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

23. CTA Benefits and Drawbacks? CTA (Abdomen, Pelvis, Bilateral Lower Legs)
Able to rotate with axial, coronal and sagital images easily
Able to scan larger segments
Easier to schedule
Able to see surrounding pathology
Drawbacks
Artifacts from calcium
No measure of flow

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

25. 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% or 90%

26. Simple Technologies Available
Effective Follow Up
Good Clinic Personnel
Home Health Care
Podiatry Visits
Skype/JPEGS
Pt in remote clinic following recent catheterization. Distal Embolization

27. Conclusions Screening for PAD:
-Obtain Non invasive Arterial Duplex or Segmental Pressures first, if abnormal
-Obtain CTA or MRA
Very similar in results compared to DSA
Useful to see immediate disease
Help to plan intervention
Replacing diagnostic angiograms

28. Conclusions
Future is very bright for CTA/MRA