Temporal lobe epilepsy visualized with PET with 11C-L-deuterium-deprenyl -: analysis of kinetic data

Objectives - The purpose of the study was to develop a simplified method for the acquisition and analysis of data from positron emission tomography (PET) using the ligand C-11-L-deuterium-deprenyl. This is motivated by an increased interest in methods to characterize gliosis in neurodegenerative diseases and epilepsy, which can be defined due to an increased expression of the enzyme MAO-B. Methods - Seven patients with temporal lobe epilepsy were investigated with PET. The tracer kinetics in different brain structures was recorded and analyzed using different models with and without a plasma input function. The derived values were correlated to literature values of H-3-deprenyl binding in frozen sections from normal human brains. Results - A good correlation was seen between in vivo binding and in vitro data, with the correlation being equally good irrespective of whether metabolite corrected plasma or modified cerebellar uptake values were used as input function. The epileptic lobe was, compared to non-epileptic, characterized by a lower initial distribution and an enhanced late accumulation of the tracer. With the applied method, it was possible to correctly identify the epileptic side in all 6 unilateral patients and 1 probable bilateral case. Conclusions - PET with C-11-L-deuterium-deprenyl gives a good correlation between calculated in vivo binding and MAO-B activity. The analysis can be simplified and blood sampling avoided if modified cerebellar time-activity data is used as a reference. Separate images of distribution volume and MAO-B binding can be generated.