TC-99M-BICISATE RELIABLY IMAGES CBF IN CHRONIC BRAIN DISEASES BUT FAILS TO SHOW REFLOW HYPEREMIA IN SUBACUTE STROKE - REPORT OF A MULTICENTER TRIAL OF 105 CASES COMPARING XE-133 AND TC-99M-BICISATE (ECD, NEUROLITE) MEASURED BY SPECT ON SAME-DAY

A multicenter study was performed in seven European centers comparing Tc-99m-bicisate with Xe-133 as a means of evaluating bicisate as a tra cer of CBF distribution in humans. The same type of single photon emis sion computed tomography (SPECT) instrument (Tomomatic) was used in al l centers. A total of 115 cases were collected, and of these 105 were considered technically adequate, comprising 18 normal subjects, 18 sen ile dementia, eight epilepsy, one brain tumor, eight chronic head trau ma, and 52 stroke cases. As expected, bicisate gave better spatial res olution than Xe. Agreement between the results of the two methods was noted in 98 cases, but not in the remaining 7, all belonging to the st roke group. These seven all suffered from a subacute stroke (11-23 day s after onset), and the disagreement in all cases consisted of bicisat e showing low count rate in the area of the infarct and Xe a normal or elevated flow (luxury perfusion) as sign of spontaneous thrombolysis with reperfusion; in fact, these seven cases comprised all the reperfu sion cases in the series. The results validate bicisate as a tracer of CBF in normal humans and in chronic brain diseases. Only in a subgrou p of subacute stroke cases does bicisate not follow CBF, as it fails t o show reperfusion hyperemia. This suggests the usefulness of bicisate in stroke cases, particularly in the subacute phase, where other SPEC T methods often present difficulties due to reflow masking the size an d the severity of the lesion.