Iodine-123 labelled PE21 for dopamine transporter imaging: influence of age in healthy subjects

The iodine-123 labelled selective ligand N-(3-iodoprop-2E-enyl)-beta P-carb omethoxy-3 beta-(4-methylphenyl)nortropane ([I-123]PE2I) has been developed and has been shown to be suitable for single-photon emission tomography im aging of the dopamine transporter. In this study the influence of age on li gand binding was investigated in 16 healthy males with an age range of 23-7 5 years. Single-photon emission tomography (SPET) imaging was performed wit h a triple-headed gamma camera. A simplified reference region model, in whi ch the input function was derived from the non-displaceable cerebellar comp artment, was used to calculate the volume of distribution in the striatum. The volume of distribution was shown to decline with age (-0.4%/year; P<0.0 05), The results were in agreement with in vivo and in vitro findings of a decline in dopamine transporter binding with age. The findings confirm the suitability of [I-123]PE2I for SPET imaging in clinical routine but emphasi ze the necessity of using age-matched controls in patient studies.