Surveillance of Peripheral Arterial Bypass Grafts with Three-Dimensional MR Angiography

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Abstract
OBJECTIVE. The purpose of this study was to use contrast-enhanced three-dimensional MR angiography to assess the patency of peripheral arterial bypass grafts of the lower extremity. SUBJECTS AND METHODS. The study included 39 patients with 45 lower limb grafts. Twenty-eight were saphenous vein grafts, 13 were expanded polytetrafluoroethylene, and two were Dacron grafts. Digital subtraction angiography correlation was available for 30 patients (31 grafts). MR angiography was performed on a 1.5-T system with a multichannel quadrature phased array peripheral vascular coil. The scanning delay was determined with a test bolus technique, using half-time to maximum signal intensity in the graft. Arterial imaging was accomplished with two three-dimensional MR angiography acquisitions with gadopentetate dimeglumine administered using an automated injector. The pelvic and femoral arteries were imaged, the MR table was repositioned, and the lower limb arteries were imaged. The three-dimensional MR angiography sequence used the following parameters: TR/TE, 5.2/1.5 msec; inversion time, 28 msec; flip angle, 30°. The proximal anastomosis, graft, and distal anastomosis were characterized as normal, stenosed, occluded, or ectatic or aneurysmatic. RESULTS. Sensitivity and specificity values for MR angiography regarding the assessment of grafts were 100% for 87 evaluable segments for which digital subtraction angiography correlation was available: stenosis (n = 10), occlusions (n = 9), ectasia or aneurysms (n = 8). Six segments could not be assessed because of the presence of intravascular stents or metallic clips. CONCLUSION. Contrast-enhanced three-dimensional MR angiography is well suited for the characterization of arterial grafts, for planning subsequent vascular interventions, and for excluding further lesions.