EVALUATION OF THE ACETAZOLAMIDE TEST - VASOREACTIVITY AND CEREBRAL BLOOD-VOLUME

Background and Purpose We evaluated the potential usefulness of the ac etazolamide test by investigating whether acetazolamide vasoreactivity reflected the change in resting cerebral blood volume caused by compe nsatory vasodilation due to a decline in cerebral perfusion pressure. Methods We measured resting and acetazolamide-activated cerebral blood flow with a stable xenon-enhanced CT system and resting cerebral bloo d volume with the subtraction technique using contrast-enhanced CT in 30 patients with various diseases. These parameters were measured in t he anterior, middle, and posterior cerebral arterial territories of bo th hemispheres separately. We evaluated the statistical relationships between resting cerebral blood volume and vasoreactivity in these thre e territories, and the significance of the correlations was tested by ANOVA/ANCOVA to adjust for the double entries. Results Significant neg ative linear relationships were demonstrated between the resting cereb ral blood volume and the change in cerebral blood flow, expressed as a percentage induced by acetazolamide activation, for the anterior (r=- .607, P=.0004), middle (r=-.551, P=.0015), and posterior (r=-.523, P=. 0078) cerebral arterial territories and between the resting cerebral b lood volume and the increase in cerebral blood flow (absolute values) for the anterior (r=-.512, P=.0164) and middle (r=-.523, P=.0001) but not the posterior (r=-.571, P=.0563) cerebral arterial territories. Co nclusions The acetazolamide test appears to be useful for the investig ation of compensatory vasodilation: the vasoreactivity can be calculat ed as the increased cerebral blood flow expressed as a percentage or a n absolute value, which both reflect cerebral blood volume directly.