PET studies with [11C]raclopride were performed using an Eminence SET-3000GCT/X (Shimadzu Corp., Kyoto, Japan). This scanner provides 99 planes with a 26-cm axial field of view, and the intrinsic spatial resolution was 3.4 mm in-plane and 5.0 mm full-width at half maximum (FWHM) axially (25 (link)). A 10-min transmission scan was acquired before an emission scan using a 137Cs line source for subsequent attenuation correction. [11C]raclopride was administered by the dual-bolus method or bolus-infusion method, and emission data were acquired in three-dimensional mode. The list-mode data were rebound to sinograms and reconstructed by filtered back-projection using a Gaussian filter (cutoff frequency, 0.3 cycle/pixel). The reconstructed in-plane resolution was 7.5 mm in FWHM and the voxel size of the reconstructed images was 2.0 × 2.0 × 2.6 mm. The head movement of each frame was corrected by frame-by-frame image realignment with attenuation correction using a resliced μ-map, as reported previously (26 (link)).
T1-weighted magnetic resonance (MR) images were acquired with a GE 3.0-T Excite system (slice thickness 1.0 mm; matrix, 256 × 256; field of view, 25 × 25 cm).
T1-weighted magnetic resonance (MR) images were acquired with a GE 3.0-T Excite system (slice thickness 1.0 mm; matrix, 256 × 256; field of view, 25 × 25 cm).