Dynamic contrast-enhanced MR angiography from the distal aorta to the ankle joint with a step-by-step technique

OBJECTIVE, The aim of this study was to visualize the arteries from the dis tal aorta to the ankle joint and to determine the accuracy of MR angiograph y for detecting stenoses and occlusions. SUBJECTS AND METHODS. Twenty-four patients with peripheral arterial occlusi ve disease underwent digital subtraction angiography and were examined on a 1.5-T MR scanner. The transit time for contrast material was determined wi th a test bolus injection. A T1-weighted three-dimensional gradient-echo se quence with short TR and TE was used for a dynamic measurement at the level of the iliac arteries, the upper leg, and the lower leg arteries. For each level a single dose of gadolinium was injected into an antecubital vein wi th an MR power injector. Maximal-intensity-projection reconstructions were calculated after subtraction of the first measurement at each level. Two ex perienced MR radiologists who were unaware of the digital subtraction angio graphy results interactively evaluated both the MIP reconstructions and the single slices on a workstation, first independently and then in a consensu s interpretation. RESULTS. With digital subtraction angiography, 80 hemodynamically significa nt stenoses and 39 occlusions were detected. For the stenoses and occlusion s, a sensitivity of 100% was found for MR angiography. The specificity for the assessment of stenoses and occlusions was 98% and 94%, respectively for the iliac arteries; 98% and 93%, respectively, for the upper leg arteries: and 94% and 95%: respectively, for the lower leg arteries. Most false-posi tive findings of occlusion were due to metal stents present in the iliac (n = 3) and upper leg (n = 4) arteries. CONCLUSION. The MR imaging technique that we used revealed the arteries fro m the distal aorta to the ankle and proved to be reliable at showing arteri al stenoses and occlusions.