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

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

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

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

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.

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

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

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

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

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%

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

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

Aortic CTA

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

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

Renal CTA/MRA

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):295-302

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

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

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

Lesion Pathology: FMD Renal Stenosis Allowed for treatment PTA plans

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

Lower Extremity

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

Lower Extremity: Epidemic

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

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

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

Angiogram Left Leg Popliteal Artery Anterior Tibial

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

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.

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

Conclusions Future is very bright for CTA/MRA