Poststenotic signal attenuation on 3D phase-contrast MR angiography: a useful finding in haemodynamically significant carotid artery stenosis

We performed blinded visual evaluation of MR angiography (MRA) films in 44 patients with unilateral carotid artery stenosis to determine whether a flo w gap and poststenotic signal attenuation on 3 D-PC MRA were useful signs o f severe carotid artery stenosis. Although nine patients with a flow gap al one had Various degrees of stenosis ranging from 22.2 to 77.3 % without any decrease in regional cerebral blood flow (rCBF), 13 patients with both a f low gap and poststenotic signal attenuation had severe stenoses of 80 % or more, with a definite decrease in baseline rCBF. The presence of both a flo w gap and poststenotic signal attenuation on 3D-PC MRA appeared to be a rel iable marker of severe carotid artery stenosis with a decrease in rCBF.