TC-99(M)-HMPAO SPET AND H-1-MRS (PROTON MAGNETIC-RESONANCE SPECTROSCOPY) IN PATIENTS WITH ISCHEMIC CEREBRAL INFARCTION

Brain Tc-99(m)-HMPAO single photon emission tomography (SPET) and H-1- MRS (proton magnetic resonance spectroscopy) were used to determine co rrelations between alterations in regional cerebral blood flow (rCBF) and changes in neuronal metabolites in 21 patients (28 examinations) w ith ischaemic cerebral infarction examined in different phases. rCBF w as determined semi-quantitatively using Lassen's linearization algorit hm. SPET provided evidence of the hypoperfused site of necrosis within a few hours after the acute event and alterations in rCBF were detect ed in both the infarcted and diaschistic areas at all stages. H-1-MRS was used to monitor the concentration of the following metabolites: N- acetyl-aspartate (NAA), creatine and phosphocreatine (CR+PCr), compoun ds containing choline (Cho) and lactate (Lac). A significant correlati on was found between reduction in rCBF and a fall in NAA and Cr+PCr in both the acute and chronic phases, but not during 'luxury perfusion' in the subacute phase. The presence of LAC in the infarcted area up to 9 months post-ictus was totally unexpected. Simultaneous SPET and H-1 -MRS thus provides additional information regarding the physiopathogen esis of cerebral ictus by clarifying the relation between alterations in rCBF and biochemical neuronal changes. We believe that NAA and Cr+P Cr concentrations are the best expression of agreement between flow an d metabolism in infarcted areas, particularly with regard to hypoperfu sed areas not clearly detectable by magnetic resonance imaging in the early post-ictus stage.