Abstract
1122
Objectives: Due to the involvement of dopamine in a variety of cognitive tasks and degenerative diseases, there has been considerable interest in measuring the extrastriatal distribution of dopamine receptors with PET. A technique suitable for mapping the distribution of the dopamine transporters (DAT) would permit a corresponding evaluation of the presynaptic dopamine reuptake system. We report an initial study using 11-C Altropane and quantitative mapping of binding potential (BP). Methods: We studied a cohort of 12 normal subjects, comprised of 6 men and 6 women with ages from 18.6-28.6 yr. Subjects received an IV injection of 5 mCi of 11C-labeled Altropane with specific activity > 800 mCi/μM. Dynamic imaging was performed for 60 min with an ECAT HR+ operating in the 3D mode. Parametric maps of BP were based on the simplified reference region method, computed using ridge regression with spatial constraint, as described by Zhou et al. The parametric maps were spatially normalized into a stereotactic coordinate system, using deformable image registration (SPM99) and a custom raclopride template. Mean BP for the cohort and its standard error were computed voxel-by-voxel as three dimensional image arrays. BP was sampled at specific voxels in structures known to be involved with the dopaminergic system. Results: [table] Conclusions: Spatial distribution of BP generally follows the trends expected of a dopaminergic tracer. With a cohort of 12 subjects, the SEM is well controlled, suggesting that this agent and method can be used to assess the integrity of the extrastriatal distribution of the DAT.
- Society of Nuclear Medicine, Inc.