VASODILATORY RESPONSES AND MAGNETIC-RESONANCE ANGIOGRAPHY - EXTRACRANIAL AND INTRACRANIAL INTRAVASCULAR FLOW DATA

This study measured the responses of both extracranial (internal carot id arteries) and intracranial (middle cerebral/angular, basilar arteri es) intravascular arterial volume flow rates to acetazolamide using ph ase-contrast magnetic resonance angiography. Twenty-eight newly studie d patients were subdivided into four groups: Group l-Nonocclusive, asy mptomatic (n = 7, or 14 carotid and middle cerebral/angular artery sid es); Group II-unilateral carotid transient ischemic attacks, nonhemody namic (embolic), varying stenoses (n = 11); Group Ill-unilateral carot id transient ischemic attacks, hemodynamic, varying stenoses (n = 5); and Group lV-unilateral carotid occlusion, asymptomatic (n = 5). The d ata were separated into nonischemic and ischemic sides so as to illust rate group differences based on vasodilatory responses to acetazolamid e. For example, the percent change in volume flow rates over baseline values for the ischemic-side middle cerebral arteries of Group III was significantly the lowest of all of the vasodilatory responses (-25 +/ - 11% vs 40 +/- 14% for group II ischemic middle cerebral/angular arte ry sides, p = 0.008). Group III patients also had significantly lower standing blood pressures (p = 0.012), higher number of transient ische mic attacks (p = 0.008), and shorter duration of events (p = 0.013). D eterminations of volume flow rate continue to assist in determining th e degree of hemodynamic compromise of a particular vascular territory.