Assessment of cerebral perfusion and cerebrovascular reserve in insulin-dependent diabetic patients without central neurological symptoms by means ofTc-99m-HMPAO SPET with acetazolamide

The detection of subclinical abnormalities in cerebral blood flow could be of great value in identifying diabetic patients at risk of stroke. The aim of this study was to assess the contribution of semiquantified post-acetazo lamide technetium-99m hexamethylpropylene amine oxime single-photon emissio n tomography (Tc-99m-HMPAO SPET) in 15 diabetic patients with no clinical h istory of central neurological disease. After baseline Tc-99-HMPAO SPET, a second SPET scan was acquired after activation of the cerebrovascular reser ve (CVR) with an injection of I g of acetazolamide (post-ACZ SPET). Semiqua ntitative analysis was made in 16 regions of interest (ROIs) drawn for each of the three supratentorial slices selected, and in two ROIs in the infrat entorial slice. The CVR was calculated in each ROI by subtracting the decay -corrected baseline images from those obtained in the post-ACZ SPET and exp ressed as the percent increase in the average counts between the two scans. Baseline perfusion and CVR values in the study group were compared with th e corresponding values in a control group. Of 750 cortical ROB studied, 332 showed a decreased CVR (44.3%). The baseline perfusion SPET study showed h ypoperfusion in 65 ROIs (8.6%) and hyperperfusion in 56 (7.4%). Of the 65 h ypoperfused regions, 66.2% had a normal CVR and 33.8% had a decreased CVR, whereas of the 56 hyperperfused regions. 51.8% had a CVR within normal limi ts and 48.2% showed a decreased CVR. In conclusion, in comparison with base line Tc-99-HMPAO SPET, the ACZ activation test provided additional informat ion in the study of cerebrovascular impairment, and allowed characterisatio n of the subclinical abnormalities in the population studied. The technique may therefore prove useful in evaluating future preventive strategies for stroke in diabetic patients.