CORRELATION OF CINE MR VELOCITY-MEASUREMENTS IN THE INTERNAL CAROTID-ARTERY WITH COLLATERAL FLOW IN THE CIRCLE OF WILLIS - PRELIMINARY-STUDY

The velocity-phase relationship intrinsic to phase-contrast magnetic r esonance (MR) angiography permits the quantitative and qualitative ass essment of blood flow. The ability to measure velocity and vessel cros s-sectional area allows noninvasive assessment of volume flow rate (VF R) in the internal carotid artery (ICA). Phase-contrast techniques als o demonstrate flow direction. Using two-dimensional cine phase-contras t angiography, the authors evaluated VFR in the ICA and collateral flo w about the circle of Willis in 15 patients with ischemic neurologic s ymptoms. The VFR in each carotid artery was correlated with the degree of stenosis and presence or absence of abnormal circle of Willis coll ateral flow. There was a correlation between a decrease in VFR and abn ormal circle of Willis collateral flow. In addition, a correlation bet ween severe stenosis and a decrease in VFR was found. In patients with ischemic neurologic symptoms without severe stenosis (< 70% diameter stenosis), no decrease in VFR was seen. It is hoped that flow quantifi cation and directional flow imaging with phase-contrast angiography wi ll help further characterize carotid artery occlusive disease by enabl ing assessment of VFR changes associated with ischemic neurologic symp toms. This study also supports the hypothesis that two mechanisms hemo dynamic and embolic-play a role in ischemic neurologic symptoms.