Positron CT of epilepsy

Positron CT was performed in two epileptic patients. Positron emitting isotopes of 11C, 13N and 18F were made at National Institute of Radiological Sciences using cyclotrone. Device of Positron CT is ''POSITOLOGICA'' which has a ring of unequally spaced 64 bithmus germanate detectors arranged in a circle, and the ring rotates contineouslly. Case 1. This is a 49 year-old man who had five years' history of convulsive seizures. CT scan reveals progressive right hemispheric atrophy, and high density area in right frontal lobe but was not enhanced with contrastmedia. Positron CT of 13NH3 shows decreased accumulation of 13N in right frontal lobe and the area surrounding the sylvian fissure. Case 2. Thirtythree year old man was found unconscious 3 years ago and convulsive seizure was noted 3 months before the Positron CT. Positron CT of 13NH3 and 18FDG reveals decreased uptake in left temporo-occipital region. Area of decrease of 18FDG is smaller than that of 13NH3. It seems that the area of decreased glucose metalism is smaller than the area of decreased perfusion. This finding of decreased uptake of 13NH3 and 18FDG in interictal state is same as report of Kuhl et al. But there are reports that cerebral blood flow is increased while interictal state measured by 133Xe method. And it is mentioned that epileptogenic focus is fluctuating state functionally and metabolically. Positron CT of epileptic patient is valuable in diagnosis and therapy, especially surgical procedure was intended. (J.P.N.)