RT Journal Article SR Electronic T1 SPECT of Serotonin Transporters Using 123I-ADAM: Optimal Imaging Time After Bolus Injection and Long-Term Test–Retest in Healthy Volunteers JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 1301 OP 1309 VO 46 IS 8 A1 Ana M. Catafau A1 Víctor Pérez A1 María M. Penengo A1 Santiago Bullich A1 Mónica Danús A1 Dolors Puigdemont A1 Juan C. Pascual A1 Iluminada Corripio A1 Jordi Llop A1 Javier Perich A1 Enric Álvarez YR 2005 UL http://jnm.snmjournals.org/content/46/8/1301.abstract AB 123I-ADAM (2-([2-([dimethylamino]methyl)phenyl]thio)-5-123I-iodophenylamine) has been recently proposed as a new serotonin transporter (SERT) ligand for SPECT. The objective of this study was to characterize 123I-ADAM in healthy volunteers. 123I-ADAM distribution in the normal brain, pseudoequilibrium interval after a single injection, normal specific uptake values, and long-term test–retest variability and reliability were investigated. Methods: Ten healthy volunteers underwent 2 SPECT sessions under the same conditions 47.6 ± 24.0 d apart. Scans were sequentially acquired from the time of 123I-ADAM intravenous injection up to 12 h after injection. Regions of interest (ROIs) for cerebellum (C), midbrain, thalamus, striatum, mesial temporal region, and cortex were drawn on MR images and pasted to corresponding SPECT slices after coregistration. Specific uptake ratios (SURs) at pseudoequilibrium and the simplified reference tissue model (SRTM) methods were used for quantification. SURs were obtained as ([region − C]/C) at each time point. Test–retest variability and reliability (intraclass correlation coefficient [ICC]) were calculated. Results: The highest 123I-ADAM specific uptake was found in the midbrain and thalamus, followed by the striatum and mesial temporal region. Quantification results using SUR and SRTM were correlated with R = 0.93 (test) and R = 0.94 (retest). SURs remained stable in all regions from 4 to 6 h after injection. Using SUR, test–retest variability/ICC were 13% ± 11%/0.74 in midbrain, 16% ± 13%/0.63 in thalamus, 19% ± 18%/0.62 in striatum, and 22% ± 19%/0.05 in mesial temporal region. Conclusion: 123I-ADAM accumulates in cerebral regions with high known SERT density. The optimal imaging time for 123I-ADAM SPECT quantification is suggested to be from 4 to 6 h after a single injection. Long-term test–retest variability and reliability found in the midbrain are comparable to that reported with other 123I-labeled SPECT ligands. These results support the use of 123I-ADAM SPECT for SERT imaging after a single injection in humans.