TC-99M HMPAO SPET IN ACUTE SUPRATENTORIAL ISCHEMIC INFARCTION, EXPRESSING DEFICITS AS MILLILITER OF ZERO PERFUSION

A comparative interim analysis was performed of clinical parameters, c omputed tomographic (CT) scan results and technetium-99m hexamethylpro pylene amine oxime single-photon emission tomography (SPET) findings o btained within 12 h of acute supratentorial ischaemic infarction. Firs t, the applicability for SPET semiquantification in this study of the ''method of Mountz'', simultaneously accounting for extent and degrees of hypoperfusion by expressing deficits as millilitre of zero perfusi on, was considered. Next, the relative contributions of perfusion SPET and CT scan in the acute stage of ischaemic infarction were compared in 27 patients (mean age 68.8 years). Finally, the correlation of SPET lesions with clinical parameters at onset was evaluated. The method o f Mountz represents a workable, accurate virtual parameter, with the a ssumption that the contralateral brain region remains uninvolved. Inte robserver reproducibility in 12 SPET studies, with lesions varying bet ween 6 and 369 cc, showed a correlation coefficent r of 0.99. In pract ice, because of inconstant dis tribution of activities in the brain, t he method can only be applied slice by slice and not on the total glob al volume. While the mean delay since the onset of symptomatology was approximately 7 h for both SPET and CT scan, SPET showed lesions conco rdant with the clinical neurological findings in 100% and CT scan in o nly 48%. One could hypothesize that SPET examinations performed later would show larger functional defects, because of the development of ad ditional functional changes secondary to biochemical alterations. Howe ver, in this regard no statistically significant differences were foun d between two subproups, taking the median of delay before SPET examin ation as cut-off. Finally, when com paring the volumes of SPET lesions during the acute stage with clinical parameters, a statistically sign ificant correlation (P<0.01) was found with the Orgogozo Scale scores describing the neurological deficit, but not with the Glasgow Coma Sca le or Frenchay Aphasia Screening Test scores obtained on admittance.