Iodine-122-labeled amphetamine derivative with potential for PET brain blood-flow studies

The positron emitter 122I (t1/2 3.6 min) was collected from a xenon-122/iodine-122 (122Xe/122I) generator and incorporated into an amphetamine analog, 2,4-dimethoxy-N,N-dimethyl-5-[122I]iodophenylisopropylamine (5-[122I]-2,4-DNNA). The remote synthesis was achieved in 3 min with a 50% radioincorporation yield and a product radiopurity of greater than 98%. 5-[122I]-2,4-DNNA was injected into a beagle dog and a brain section imaged with positron emission tomography (PET). The uptake and retention of 5-[122I]-2,4-DNNA was compared to that of 82Rb+ in the same animal. Dynamic PET activity data were obtained 0-20 min postinjection of 5-[122I]-2,4-DNNA and showed rapid uptake by brain and good cerebral/extracerebral tissue distinction. A whole-body scan of a dog was also obtained with 5-123I-2,4-DNNA showing uptake in brain, lung, and other body organs. The feasibility of incorporating 122I into an extracted brain perfusion agent for use with PET is demonstrated.