Redistribution of cerebropetal blood flow in patients with carotid artery stenosis measured non-invasively with fast cine phase contrast MR angiography

The purpose was to evaluate the blood flow redistribution in the neck vessels of patients with internal carotid artery (ICA) stenosis. Eighty-six patients with ICA stenosis underwent contrast-enhanced magnetic resonance angiography (CEMRA) and fast 2D phase contrast (2D-PC) sequence to measure the mean blood flow (MBF) of ICA, basilar artery (BA) and middle cerebral artery (MCA). CEMRA revealed 53 severe stenoses, 45 moderate stenoses and 3 occluded vessels. Patients with a unilateral severe ICA stenosis had a significantly reduced MBF of the ICA compared to the control group; the MBF reduction of the severely stenosed ICA was less conspicuous if associated with a controlateral severe stenosis. The MBF of the BA increased significantly in the presence of the bilateral severe ICA stenosis and in the ICA occlusion. The MBF of the MCA was unchanged in the presence of various degrees of ICA stenosis. Measurement of MBF with fast PC MRA permits cerebropethal blood flow assessment and gives additional information in grading ICA stenosis. The reduced MBF of a severe ICA stenosis has to be considered with caution since it depends also on the status of the controlateral ICA and may be considered a confident parameter only in case of unilateral carotid stenosis.