Use of technetium-99m hexamethylpropylene amine oxime SPET for the study of cerebral blood flow reactivity after acetazolamide infusion in patients with Behcet's disease

The purpose of this study was to characterise the nature of the baseline pe rfusion defects found in patients with Behcet's disease using hexamethylpro pylene amine oxime single-photon emission tomography in conjunction with ac etazolamide test (Acz SPET). Eleven patients underwent both baseline and Ac t SPET. Regions of interest (ROIs) were drawn on the areas with decreased p erfusion (D-ROI) and, in the same section, on areas with normal perfusion ( N-ROI). The ROIs were then repositioned on the corresponding section on Act SPET. The mean ROI counts were then transformed into a perfusion index val ue (PIV) with reference to the global brain counts. In total we found 24 D- ROIs (17 in the cortical and 7 in subcortical grey matter). The influence o f Act infusion was selectively registered in the D-ROIs, where PIVs changed from 1.23+/-0.17 (baseline SPET) to 1.63+/-0.23 (Acz SPET) (P<0.001). No s ignificant difference was seen in the N-ROIs (1.46+/-0.21 and 1.40+/-0.17, respectively, on baseline SPET and Act SPET). Our results demonstrate that Act infusion increases the regional cerebral blood flow within baseline gre y matter perfusion defects. This finding suggests that baseline perfusion a bnormalities could reflect a disconnection rather than local vasculitic inv olvement.