ABSTRACT
UNLABELLED: 123I-ADAM is a novel radioligand for imaging of the brain serotonin transporters (SERTs). Traditionally, the analysis of brain receptor studies has been based on observer-dependent manual region of interest definitions and visual interpretation. Our aim was to create a template for automated image registrations and volume of interest (VOI) quantifications and to show that an automated quantification method of 123I-ADAM is more repeatable than the manual method. PATIENTS, METHODS: A template and a predefined VOI map was created from 123I-ADAM scans done for healthy volunteers (n = 15). Scans of another group of healthy persons (HS, n = 12) and patients with bulimia nervosa (BN, n = 10) were automatically fitted to the template and specific binding ratios (SBRs) were calculated by using the VOI map. Manual VOI definitions were done for the HS and BN groups by both one and two observers. The repeatability of the automated method was evaluated by using the BN group. RESULTS: For the manual method, the interobserver coefficient of repeatability was 0.61 for the HS group and 1.00 for the BN group. The introobserver coefficient of repeatability for the BN group was 0.70. For the automated method, the coefficient of repeatability was 0.13 for SBRs in midbrain. CONCLUSION: An automated quantification gives valuable information in addition to visual interpretation decreasing also the total image handling time and giving clear advantages for research work. An automated method for analysing 123I-ADAM binding to the brain SERT gives repeatable results for fitting the studies to the template and for calculating SBRs, and could therefore replace manual methods.
Subject(s)
Cinanserin/analogs & derivatives , Automation/methods , Cinanserin/analysis , Humans , Image Processing, Computer-Assisted , Iodine Radioisotopes/analysis , Observer Variation , Reference Values , Reproducibility of Results , Tomography, Emission-Computed, Single-Photon/methodsABSTRACT
[(123)I]ADAM [2-((2-((dimethylamino)methyl)phenyl)thio)-5-iodophenylamine (ADAM)] has recently been shown to be a very promising imaging ligand for the detection of serotonin transporters (SERT) in human brain, because of its high specificity for SERT. [(123)I]ADAM has previously been used only for animal studies. In this work, we investigated the radiation dosimetry and biodistribution of [(123)I]ADAM based on whole-body scans in healthy human volunteers. Following the administration of 196+/-20 MBq (range 157-220 MBq) [(123)I]ADAM, serial whole-body images were performed up to 24 h. Estimates of radiation absorbed dose were calculated using the MIRDOSE 3.0 program with a dynamic bladder model. Twelve source organs were considered in estimating absorbed radiation doses for organs of the body. The highest absorbed organ doses were found to the lower large intestine wall (8.3.10(-2) mGy/MBq), kidneys (5.2.10(-2) mGy/MBq), urinary bladder wall (4.9.10(-2) mGy/MBq) and thyroid (4.3.10(-2) mGy/MBq). The effective dose was estimated to be 2.2.10(-2) mSv/MBq. The results suggest that [(123)I]ADAM is of potential value as a tracer for single-photon emission tomography imaging of serotonin receptors in humans, with acceptable dosimetry and high brain uptake.
