ASSESSMENT OF CEREBROVASCULAR REACTIVITY BY DYNAMIC SUSCEPTIBILITY CONTRAST-ENHANCED MR-IMAGING

In patients with cerebrovascular disease the acetazolamide (ACZ) test is performed to evaluate the decrease in cerebral perfusion pressure ( CPP) through the investigation of the vasomotor reactivity (VMR). This latter is currently assessed with ACZ with several methods. Recently, magnetic resonance imaging (MRI) techniques have been developed that are sensitive to stimulus-induced changes in ii blood flow. Dynamic su sceptibility contrast material-enhanced gradient-echo MRI techniques ( DSC-MRI) might be an attractive tool to assess VMR. We aimed to test t he ability of DSC-MRI in the assessment of VMR. Relative hemodynamic p arameters rCBV, MTT, and rCBF were evaluated at baseline after the fir st injection of gadopentetate dimeglumine and 10 min after the intrave nous administration of ACZ (1 g) with a second bolus of contrast agent . Assessment of hemodynamic parameters was performed over the whole he misphere and also within regions of interest. The significances of the mean differences, before and after ACZ, were assessed with repeated-m easures ANOVA with two within factors: laterality (right-left) and ACZ . DSC-MRI with ACZ test was performed in ten healthy controls (aged 51 .4+/-16.2 years). The cerebral hemispheric ratio for the three paramet ers (cerebral blood volume (CBV), mean transit time (MTT), and cerebra l blood flow (CBF)) ranged between 1.01 and 1.03. The mean gray matter -to-white matter ratio for CBV, CBF and MTT were 2.44, 2.41 and 1.05, respectively. As the laterality effect was not significant, left and r ight hemispheric values were averaged. A significant increase of all h emodynamic parameters was observed after ACZ (P<0.01-0.001). The same changes for CBV, CBF and MTT were observed after ACZ according to the regions of interest (P<0.006-0.015). DSC-MRI is a non-invasive method which enables the assessment of VMR. This technique may be added to an y conventional MRI in order to detect a hemodynamic impact of an ICA s tenosis. Therefore, it might be useful in determining the appropriate management when the indication for surgical versus medical therapy is in question. (C) 1997 Elsevier Science B.V.