The main target of MPH in the brain is the dopamine transporter (DAT) [6]. There is now an exquisitely sensitive methodology to measure DAT occupancy using C-11 Altropane and Positron Emission Tomography (PET) [7]. The time course of decay of the C-11 Altropane permits repeated imaging, thus allowing documentation of the pharmacokinetics of DAT receptor occupancy. A group at Massachusetts General Hospital has previously documented the central nervous system pharmacokinetics of several psychiatric drugs using similar techniques [8-12].