Brain kinetics of the new selective serotonin transporter tracer [123I]ADAM in healthy young adults

Recently, the tracer (123)[-2-([2-({dimethylamino}methyl)phenyl]thio)-5-iodophenylamine ([I-123]ADAM) has been developed for selective imaging of serotonin transporters (SERTs) with single photon emission computed tomography (SPECT). The Purpose of this study was to develop an [I-123]ADAM SPECT protocol for clinical studies in young adults. Methods: We examined the time course of [123 I]ADAM binding to central SERTs, in eight healthy young volunteers up to 6 h postinjection. Results: We found that the time of peak-specific [I-123]ADAM binding was highly variable among subjects, but specific binding in the SERT-rich (hypo)thalamus peaked within 5 h postinjection in all subjects. Moreover, in this brain area, binding ratios of specific to nonspecific binding did not significantly change between 3 and 6 h postinjection, and peaked 5 h postinjection. Conclusions: Five hours postinjection may be optimal for single-scan [I-123]ADAM SPECT studies in humans, but more work is needed to assess the accuracy of the 5-h tissue ratio as a measure of SERT in the brain. (c) 2006 Elsevier Inc. All rights reserved.