18F-ADAM PET in healthy and drug-naive depressant subjects

Abstract

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Objectives: Serotonin transporters (SERT) play a major role in modulating serotonergic neuronal function. The study was undertaken to image central SERT using 18F-ADAM PET in healthy and drug naïve depressant subjects. Methods: Four healthy and 4 drug-naïve major depressant subjects (based on DMS-IV criteria) were studied. Each subject received a dynamic imaging for 2 h after 18F-ADAM (185 MBq) intravenous bolus injection, using a 3D mode PET scanner (EXACT HR+, Siemens, USA). Except for visual inspection, the distribution volume ratios (DVR) and binding parameters (Logan plot) of the raphe nucleus (RN), thalamus (TH), striatum (ST), frontal (FR) and occipital (OC) regions in reference to cerebellum were measured in reference to the corresponding dedicated brain computerized tomography. Results were expressed as mean ± SD. Results: By visual inspection, there were discernable uptake of 18F-ADAM in the RN, TH, ST, FR and OC of the controls and less uptake in naïve patients. Averaged DVR of the RN, TH, ST, FR and OC at 1h post-injection were 3.1 ± 0.6, 2.3 ± 0.3, 2.6 ± 0.5, 1.5 ± 0.1 and 1.4 ± 0.2 in the controls, and 1.78 ± 0.1, 1.64 ± 0.1, 1.6 ± 0.2, 1.0 ± 0.2 and 0.9 ± 0.1 in the naïve patients (43, 35, 30, 31 and 36% decrease compared to the controls; p< 0.05 respectively). The Logan plot also showed a comparable pattern with 50, 34, 28, 29 and 38% decrease compared to the controls. No major side effect was found during and 8 wk after imaging. Conclusions: The brain distribution of 18F-ADAM in humans appears correlated with the known distribution of SERT. Our results suggest that the 18F-ADAM PET might be a useful tool in assessing status of human brain SERT.