Cardiac-gated two-dimensional phase-contrast MR angiography of lower extremity occlusive disease.

Abstract

The purpose of this study was to evaluate our capability to use coronally acquired, cardiac-gated two-dimensional phase-contrast MR angiography (MRA) to correctly detect and grade arteriosclerotic lesions from the aortic bifurcation to the popliteal artery. One hundred fifteen patients with a total of 253 arteriosclerotic lesions proven by intraarterial digital subtraction angiography were examined prospectively by two-dimensional phase-contrast MRA. MRA was performed from the aortic bifurcation to the popliteal trifurcation. Imaging parameters were TR/TE, 83/9 msec; flip angle, 11 degrees; matrix, 256 x 192; acquisitions, two; slice thickness, 80 mm; and field of view, 320 mm. ECG gating was used routinely and eight to 10 phases were acquired during the cardiac cycle. Velocity encoding was set to 30 cm/sec in the iliac arteries and to 20 cm/sec in the femoral and popliteal arteries. Detected stenoses were graded in the following manner: 1% to less than 50% stenosis, group 1; 50% to less than 75% stenosis, group 2; 75% to less than 100% stenosis, group 3; and total occlusion, group 4. All arteriosclerotic lesions were revealed by MRA. Two hundred seventeen of 253 lesions were also graded correctly. Sensitivity was 95%, specificity was 90%, positive predictive value was 90%, and negative predictive value was 96%. The weighted kappa index was (.92). Sensitivity and specificity for occlusions were both 100%; for high-grade stenoses, 94% and 91%, respectively; for moderate stenoses, 84% and 94%, respectively; and for mild stenoses, 79% and 100%, respectively. Two-dimensional phase-contrast MRA can provide MR angiograms with high sensitivity and specificity for high-grade stenoses in a reasonable amount of time in patients with peripheral artery occlusive disease.