Technetium-99m HMPAO SPET in acute supratentorial ischaemic infarction, expressing deficits as millilitre of zero perfusion

Abstract

A comparative interim analysis was performed of clinical parameters, computed tomographic (CT) scan results and technetium-99m hexamethylpropylene amine oxime single-photon emission tomography (SPET) findings obtained within 12 h of acute supratentorial ischaemic infarction. First, 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 perfusion, 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 of Mountz represents a workable, accurate virtual parameter, with the assumption that the contralateral brain region remains uninvolved. Interobserver reproducibility in 12 SPET studies, with lesions varying between 6 and 369 cc, showed a correlation coefficient r of 0.99. In practice, because of inconstant distribution of activities in the brain, the method can only be applied slice by slice and not on the total global volume. While the mean delay since the onset of symptomatology was approximately 7 h for both SPET and CT scan, SPET showed lesions concordant with the clinical neurological findings in 100% and CT scan in only 48%. One could hypothesize that SPET examinations performed later would show larger functional defects, because of the development of additional functional changes secondary to biochemical alterations. However, in this regard no statistically significant differences were found between two subproups, taking the median of delay before SPET examination as cut-off.(ABSTRACT TRUNCATED AT 250 WORDS)