Background
The role of serotonin in many neuropsychiatric diseases necessitates the development of reliable measures of serotonin receptor binding in humans. In this study we assessed the reproducibility of [18F]altanserin for measurement of 5-HT2A receptors in humans.
Methods
Six healthy men aged from 33 to 67 years were investigated with PET-[18F]altanserin using a bolus-infusion schedule to obtain steady state of tracer in blood and tissue. Each person was PET scanned twice with an interval of 2–14 days. Binding potential (BP) data were obtained for [18F]altanserin in three automatically defined brain regions: Frontal cortex, cingulate and striatum. Two different outcome measures were evaluated: BP1 (Cvoi – Cref)/Cplasma) and BP2 ((Cvoi – Cref)/Cref).
Results
Both BP1 and BP2 showed higher reproducibility in brain areas with high 5-HT2A receptor binding. For the BP1 measurements the mean variability of the difference (100×ABS(test – retest)/(mean test and retest)) was: Frontal cortex (5.4%), cingulate (6.1%) and striatum (17%). For BP2 the variability was: Frontal cortex (7.6%), cingulum (10.2%) and striatum (19.7%). Intraclass correlation between test and retest for same regions was for BP1: 0.85, 0.69, and 0.04 and for BP2 0.91, 0.87, and 0.63.
Conclusion
These data suggest that PET imaging with [18F]altanserin permits calculation of reproducible measures of 5-HT2A receptor in areas with high tracer binding and supports feasibility of continuing using [18F]altanserin in evaluation of mental diseases.