Vasodilatory response of border zones to acetazolamide before and after endarterectomy - An echo planar imaging-dynamic susceptibility contrast-enhanced MRI study in patients with high-grade unilateral internal carotid artery stenosis

Background and Purpose-The importance of hemodynamic changes related to a h igh-grade internal carotid artery (ICA) stenosis remains a matter of contro versy. Areas between the vascular territories of major cerebral arteries, n amely, the border zones, may be selectively vulnerable to hemodynamic alter ation. The aim of this study was to search for any hemodynamic impact of ca rotid endarterectomy (CEA) on vasodilatory response, in particular, within the border zones, by means of multislice dynamic susceptibility contrast MR I. Methods-Thirteen patients with a high-grade unilateral ICA stenosis (>80%) were examined. Relative regional cerebral blood volume (rrCBV) was determin ed separately for white matter, gray matter, and anterior and posterior bor der zones by the acetazolamide test. A vasomotor reactivity index was evalu ated from the rrCBV values, Values from the ipsilateral hemisphere were com pared with contralateral ones, before and after CEA. Results-Before CEA, rrCBV values in the anterior border zones were signific antly (P<0.05) higher in the ipsilateral hemisphere than in the contralater al hemisphere. A decrease in vasomotor reactivity indexes was also observed in the lesion side, but the difference from the contralateral side was not statistically significant. In posterior border zones, no differences in rr CBV or vasomotor reactivity were found between the ipsilateral and the cont ralateral hemispheres. After CEA, the rrCBV asymmetry in the anterior borde r zones cleared. Conclusions-High-grade ICA stenosis with efficient primary collateral pathw ays may have an early limited hemodynamic impact within border-zone areas. The favorable course of these abnormalities after surgery suggests an addit ional benefit of CEA at this stage.