Time-Resolved Imaging of Contrast Kinetics (TRICKS) Magnetic Resonance Angiography (MRA) Can Replace Diagnostic Angiography in Infra-Geniculate Arterial Occlusive Disease

Matthew Mell, MD, Girma Tefera, MD, David Siepman, MD, Frank Thornton, MD and William Turnipseed, MD
Surgery, University of Wisconsin, Madison

Objective: The diagnostic accuracy of MRA in the infrapopliteal arterial segment is not well defined. The purpose of this study was to evaluate the clinical utility and diagnostic accuracy of TRICKS MRA compared to contrast angiography (CA) in planning for percutaneous interventions of popliteal and infrapopliteal arterial occlusive disease.
Methods: Patients who underwent percutaneous lower extremity interventions for popliteal or tibial occlusive disease were identified for this study. Pre-procedual TRICKS MRA was performed using 1.5 Tesla MRI scanners (GE Healthcare, Waukesha WI) with a flexible peripheral vascular coil (Medical Advances Inc, Milwaukee WI), using Time-Resolved Imaging of Contrast Kinetics (TRICKS) technique with gadodiamide injection. Contrast angiogram (CA) was performed using standard digital subtraction technique in angiography suite with a 15 inch image intensifier. CA was considered the gold standard.The MRA and CA images were then evaluated in a blinded fashion by a radiologist and a vascular surgeon. The popliteal artery and tibio-peroneal trunk were evaluated separately while the tibial arteries were divided into proximal, mid, and distal segments. Each segment was interpreted as either normal (0-49% stenosis), stenotic (50-99% stenosis), or occluded (100%). Lesion morphology based on TASC classification was also evaluated. We calculated percent agreement between the studies as well as sensitivity and specificity of MRA. The clinical utility of pre-procedural MRA was also assessed in terms of identifying arterial access site as well as predicting technical success of the percutaneous treatment.
Results: 150 arterial segments in 30 limbs of 27 patients were available for comparison. When evalueated by TASC classification, TRICKS MRA correlated with CA in 83% of the time for popliteal and 88% in the infrapopliteal segments. MRA correctly identified hemodynamically significant stenotic disease of the popliteal artery with a sensitivity and specificity of 94% and 92%, and of the tibial arteries with a sensitivity and specificity of 100% and 84% respectively. When evaluating for stenosis vs. occlusion, MRA interpretation agreed with CA 90% of the time. Disagreement occurred in 15 arterial segments, most commonly in distal tibioperoneal arteries. MRA mis-diagnosed occlusion for stenosis in 11/15 segments, and stenosis for occlusion in 4/15 segments. Arterial access was accurately planned based on pre-procedural MRA findings in 29 of 30 patients. MRA predicted technical success 83% of the time. Five technical failures were due to inability to cross arterial occlusions, all accurately identified by MRA.
Conclusion: TRICKS MRA is an accurate method of evaluating patients for popliteal and infrapoplitial arterial occlusive disease, and it can be used for planning percutaneous intervention.