99mTc-hexamethylpropylene amine oxime SPECT and X-ray CT in acute cerebral ischaemia

Early diagnosis of acute cerebral ischaemia is still unsatisfactory, because X-ray computed tomography (CT) does not reveal the site and extent of hypoperfusion within the first 24 h. Single photon emission computed tomography (SPECT) using 99mTc-hexamethylpropylene amine oxime (HMPAO) may offer earlier information, since the distribution of HMPAO follows the actual cerebral perfusion pattern. We therefore investigated 53 patients suffering from acute cerebral ischaemia (10 with transient ischaemic attacks, 9 with prolonged ischaemic reversible neurological deficits, 34 with completed stroke). SPECT and CT examinations were performed on days 1, 3, and 14. On day 1, SPECT revealed hypoperfused areas in 42 patients, whereas CT showed hypodensities only in 5. The sensitivity of SPECT was higher in cortical compared with subcortical ischaemia. In patients suffering from reversible neurological deficits SPECT normalized in the follow-up, corresponding to clinical improvement. In completed stroke, SPECT demonstrated variable perfusion patterns with hypo-, normo-, and hypoperfused areas on day 3 and especially on day 14. In contrast to CT, HMPAO SPECT leads to early diagnosis of cerebral ischaemia, in particular within the cerebral cortex.