Reproducibility of in vivo brain measures of 5-HT2A receptors with PET and[F-18]deuteroaltanserin

The test/retest reproducibility of brain measures of 5-HT2A receptors with positron emission tomography (PET) and [F-18]deuteroaltanserin was examined in a group of eight healthy human subjects. PET measures of 5-HT2A recepto rs were obtained under an equilibrium paradigm, with a 40-min PET acquisiti on starting approximately at 300 min (308 +/- 11 min) after bolus plus cons tant infusion of the radiotracer. Three brain outcome measures were obtaine d at equilibrium, V-3 (ratio of specific brain uptake to free parent plasma concentration of radiotracer), V-3' (ratio of specific brain uptake to tot al parent plasma concentration) and RT (ratio of specific to non-displaceab le brain uptakes). V-3' and RT had high test/retest reproducibility, as mea sured by mean intra-sudject% change for cortical brain areas of 14.1 and 11 .0%, respectively. They also had high reliability, as measured by mean intr a-class correlation coefficients (ICC) for cortical brain areas of 0.86 and 0.88, respectively. V-3 had low test/retest reproducibility, due to high v ariability in the measures of free parent tracer in plasma. This study supp orts the feasibility of equilibrium imaging of 5-HT2A receptors with PET an d [F-18]deuteroaltanserin. The equilibrium imaging, method with [F-18]deute roaltanserin allows a single acquisition and blood measurement to provide a n image whose pixel values equal a receptor volume of distribution. Since t he single image pixel values are proportional to receptor densities, the im ages can be used in pixel-by-pixel statistical methods, such as SPM, to ass ess the distribution and density of 5-HT2A receptors in neuropsychiatric di sorders. (C) 2001 Published by Elsevier Science Ireland Ltd.