MR angiography of tibial runoff vessels: imaging with the head coil compared with conventional arteriography

We compared peripheral vascular MR angiography done with a standard transmit-receive head coil with conventional arteriography for identifying and evaluating runoff vessels below the knee.

We examined 55 legs in 31 symptomatic patients with both conventional contrast angiography and gradient-echo two-dimensional time-of-flight MR angiography. Both legs of patients were placed in a standard transmit-receive head coil for MR angiography and were imaged simultaneously. For evaluation of stenoses, images of vessels were divided into 10 segments, and each segment was graded on a four-point scale.

In the 393 native vascular segments evaluated, the sensitivity of MR angiography in identifying normal vessels was 95% and the specificity was 98%. In detecting segmental occlusion, MR angiography was 98% sensitive and 97% specific. Sensitivity and specificity for stenoses greater than 75% were 98% and 96%, respectively, and for stenoses greater than 50%, they were 98% and 95%, respectively. Interpretative discrepancies were found in 35 vessel segments in 18 legs; none was of clinical relevance. Of all vessel segments shown as occluded by conventional angiography, 1% appeared patent on MR angiograms. No vessel segments shown as normal on MR angiograms were found to be occluded on conventional angiograms.

When performed simultaneously on both legs of symptomatic patients, 2D time-of-flight MR angiography with a standard transmit-receive head coil provides a time-efficient and highly sensitive and specific means of evaluating below-knee runoff.