PET imaging of functional 5-HT1A receptors with [18F]F13640: From PET kinetics modeling to static Standardized Uptake Values Ratio
Résumé
Purpose: F13640 is a highly selective serotonin 5-HT 1A receptor ligand with agonist properties identied as a PET radiopharmaceutical candidate. In previous work, we showed the possibility to use long dynamic PET acquisition (225 min) combined with simplied kinetic modelling for [ 18 F]F13640 quantication. In this work, we assessed the feasibility of static acquisition and quantication using standardized uptake value ratio (SUVR) as an alternative. Methods: Test-retest PET-MRI scans of 225 min were conducted in eight healthy male volunteers. For 17 brain regions, distribution volume ratios (DVR) were calculated from the whole kinetics using Logan plot modelling method with the cerebellum white matter as reference region. For the same regions, SUVR were also calculated from static images, for four 20-minute and four 10-minute time-intervals at various time of uptake. Reliability between SUVR and DVR measures were studied, and test-retest parameters were assessed between PET sessions for each time-interval. Results: Reproducibility of measures of SUVR compared to DVR were excellent, whatever the time interval (p < 0.001). For the 20-min. time-intervals, SUVR 150-170 showed the best reproducibility and correlation parameters (R 2 = 0.95 ± 0.03, intercept = 0.06 ± 0.02, slope = 0.95 ± 0.01). As well, for the 10-min. time-intervals, SUVR 150-160 showed the best correlation (R 2 = 0.94 ± 0.03, intercept = 0.07 ± 0.02, slope = 0.94 ± 0.01). SUVR reproducibility between test-retest sessions was also excellent for each time-interval. These results were valid for pooled regions as well as at regional level. Conclusion: This study conrms the feasibility of static acquisitions to facilitate clinical use of the [ 18 F]F13640 radiopharmaceutical to image functional 5-HT 1A receptors. This involves off-camera injection, 10 to 20 mins static acquisition duration, and quantication using SUVR, while improving patient comfort.