MONOAMINE-OXIDASE-B SINGLE-PHOTON EMISSION TOMOGRAPHY WITH [I-123] RO-43-0463 - IMAGING IN VOLUNTEERS AND PATIENTS WITH TEMPORAL-LOBE EPILEPSY

Imaging of monoamine oxidase of subtype B (MAO B) is of interest in va rious neurological diseases. In the past non-invasive assessment of MA O B has only been possible with positron emission tomography (PET) lig ands. Given the limited availability of PET, 3 single-photon emission tomography (SPET) ligand would be desirable. In this study SPET imagin g with the new MAO B inhibitor [I-123]Ro 43-0463 was performed in five volunteers and nine patients with temporal lobe epilepsy (TLE). In tw o volunteers a second study was performed 12 h following blockade with deprenyl. In the TLE patients the tracer was administered as bolus (n = 4) or as prolonged infusion (n = 5). The regional uptake pattern co rrelated well with the known distribution of MAO B. In the two blockin g studies ligand uptake was substantially reduced compared with baseli ne. In the TLE patients increased uptake was found in the ipsilateral mesial temporal lobe and, surprisingly, in the ipsilateral putamen. Th is study indicates the potential of the new SPET ligand [I-123]Ro 43-0 463 to map MAO B concentration in the human brain. The new finding of in creased MAO B in the putamen of TLE patients needs further studies to elucidate its exact pathophysiology.