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

Abstract 

Recently, the tracer ¹²³I-2-([2-({dimethylamino}methyl)phenyl]thio)-5-iodophenylamine ([¹²³I]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 [¹²³I]ADAM SPECT protocol for clinical studies in young adults.

Methods

We examined the time course of [¹²³I]ADAM binding to central SERTs in eight healthy young volunteers up to 6 h postinjection.

Results

We found that the time of peak-specific [¹²³I]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 [¹²³I]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.

Keywords: Serotonin transporter imaging, SPECT, [¹²³I]ADAM, Human, Brain kinetics