OPTIMIZED INTERICTAL HMPAO-SPECT IN THE EVALUATION OF PARTIAL EPILEPSIES

Interictal blood flow single photon emission computed tomography (SPEC T) has been considered to be of limited value in the investigation of patients with partial epilepsies. Newer SPECT technologies using brain dedicated multiple detector systems have not been fully evaluated. To study the usefulness of an optimized SPECT technique, we scanned 40 e pilepsy patients and ten normal subjects. Interictal [Tc-99m]hexamethy lpropylene amine oxime (HMPAO) SPECT scans were acquired using the GE/ CGR Neurocam triple-headed brain-dedicated system. The results of a qu alitative analysis of the scans were compared to EEG and optimised MRI findings. Eight of the normal subjects and one of 40 patients had nor mal SPECT scans. There was a comparable concordance of lateralization between SPECT, MRI and EEG; The majority of our patients had mesial te mporal pathology on MRI. Perfusion abnormalities extending beyond the mesial temporal area were common and did not simply relate to structur al abnormalities. Quantification of blood flow in multiple brain regio ns revealed that hypoperfusion did not occur at random. Perfusion in t he mesial temporal lobe was related to perfusion in anatomically and f unctionally related ipsilateral and contralateral brain regions. These hypoperfused areas probably reflect dysfunctioning areas which are re lated to the epileptogenic process.