REPRODUCIBILITY OF THE DISTRIBUTION OF CARBON-11-SCH-23390, A DOPAMINE D-1 RECEPTOR TRACER, IN NORMAL SUBJECTS

The reproducibility of [C-11]SCH 23390 in PET was studied in 10 normal human subjects. Methods: The scan-to-scan variation of several measur es used in PET data analysis, including the radioactivity ratio, plasm a-input Logan total distribution volume (DV), plasma-input Logan DV ra tio (DVR) and tissue-input Logan B-max/K-d values, was determined. Res ults: There were significant correlations among the radioactivity rati o, plasma-input DVR and tissue-input B-max/K-d. With the cerebellum as the reference region, these three measures also had high reliability (86%-95%), high between-subject s.d. (7.7%-11.3%) and small within-sub ject s.d. (2.3%-3.6%), indicating that they are comparable and useful measures for the assessment of dopamine D-1 receptor binding. Conclusi on: The radioactivity ratio and the tissue-input BmaxKd may be preferr ed methods for the evaluation of dopamine D-1 receptor binding because these two methods do not require arterial blood sampling and metaboli te analysis. Our results show that cerebellum is a reliable reference region for SCH 23390. When the Logan plasma-input function method is u sed in data analysis for SCH 23390, DVRs rather than total DV values s hould be used because of the poor reliability of the DV values and the ir lack of correlation with other measures. Carbon-11-SCH 23390 is thu s a reliable and reproducible ligand for the study of dopamine D-1 rec eptor binding by PET.