Measurement of cortical dopamine D1 receptor binding with [11C]SCH 23390:: A test-retest analysis

[C-11]SCH 23390 is a standard ligand for positron emission tomography (PET) studies on striatal dopamine D-1 receptors. Its usefulness for cortical D-1 receptor quantification in human PET studies has been questioned but has not been addressed previously. The authors tested the reproducibility of [C-11]SCH 23390 binding potential (BP) in cortical areas in five healthy volunteers using three-dimensional PET. Measurement of D-1 receptor BP was reproducible in basal ganglia, as well as in all cortical areas studied (intraclass correlation coefficients between 0.81 and 0.92). The absolute variability in cortical areas was 9.21% +/- 0.07%. The reproducibility or cortical D-1 receptor BP measurement with [C-11]SCH 23390 is equal to that observed with a more recent D-1-ligand, [C-11]NNC 112. [C-11]NNC 112 produces slightly higher specific-to-nonspecific binding ratios but has markedly slower kinetics resulting in a need for a longer scan time. These aspects should be considered when designing studies on the cortical D-1-like receptors.