MRA FLOW QUANTIFICATION IN PATIENTS WITH A SYMPTOMATIC INTERNAL CAROTID-ARTERY OCCLUSION

Background and Purpose Flow measurements in the collateral arteries of patients with internal carotid artery (ICA) occlusions may be importa nt to estimate the risk of future stroke. Quantitative flow measuremen ts in cerebropetal vessels can be reliably assessed by means of magnet ic resonance angiography (MRA). Methods Fifty-four patients with trans ient or minor ischemic neurological deficits and an angiographically p roven ICA occlusion and 16 control subjects underwent two-dimensional phase-contrast MRA quantitative flow measurements through the common c arotid arteries, basilar artery, ICAs, and middle cerebral arteries (M CA). Results Patients with a unilateral ICA occlusion and a 0% to 69% stenosis of the contralateral ICA had increased flow in the contralate ral ICA (P<.005) and in the basilar artery (P<.005) compared with cont rol subjects. Even patients with a 70% to 99% stenosis contralateral t o the ICA occlusion had increased flow in the ICA (P<.05) as well as i ncreased flow in the basilar artery (P<.001). Total cerebropetal flow was not significantly different between these patients and control sub jects. Patients with bilateral ICA occlusions had an increased flow in the basilar artery (P<.001), while the total cerebropetal flow was le ss than in control subjects (P<.001). In all patients, how was decreas ed in the ipsilateral MCA (P<.001) and in the contralateral MCA (P<.05 ). Conclusions The contralateral ICA is the main supplying artery in p atients with an ICA occlusion. Total cerebropetal flow decreases only when both ICAs are occluded. In patients with symptomatic ICA occlusio ns, an open contralateral ICA is probably important to retain the cere bral blood flow within normal limits.