Simultaneous [99mTc]TRODAT-1 and [123I]ADAM Brain SPECT in Nonhuman Primates

Purpose  This study examined the feasibility of simultaneous dopamine and serotonin transporter imaging using ¹²³I]ADAM and ^99mTc]TRODAT-1 single photon emission computed tomography (SPECT). Procedures  Simultaneous ¹²³I]ADAM (185 MBq) and ^99mTc]TRODAT-1 (740 MBq) SPECT was performed in three age-matched female Formosan rock monkeys. An asymmetric energy window was used for dual, and symmetric energy windows were used for single-isotope imaging. Oral fluoxetine (20 mg) and intravenous methylphenidate HCl (1 mg/kg) were given 24 h and 10 min, respectively, before dual-isotope SPECT to test imaging specificities of ¹²³I]ADAM and ^99mTc]TRODAT-1. Results  Comparable image quality and uptake ratios between dual- and single-isotope SPECT scans were found. Dual-isotope SPECT in fluoxetine-pretreated monkeys showed decreased uptake of ¹²³I]-ADAM, but not of ^99mTc]TRODAT-1. Dual-isotope SPECT in methylphenidate-pretreated monkeys showed decreased ^99mTc]TRODAT-1 uptake without affecting ¹²³I]-ADAM uptake. Conclusion  Simultaneous ¹²³I]-ADAM and ^99mTc]TRODAT-1 SPECT appears promising in nonhuman primates and may provide a suitable preclinical model with further clinical implications.