Hrrt pet scanner

Radiosynthesis of [¹¹C]UCB-J was modified on the basis of Nabulsi et al. [37 (link)], as described in detail in the Supplementary file. All participants were scanned with a high-resolution research tomography (HRRT) PET scanner (CTI/Siemens, Knoxville, TN, USA). Following a six-min transmission scan, a 120 min PET scan was started at the time of intravenous [¹¹C]UCB-J bolus injection (over ~20 sec). PET data were acquired in 3D list mode and reconstructed into 40 frames (8 × 15 s, 8 × 30 s, 4 × 60 s, 5 × 120 s, 10 × 300 s, 5 × 300 s) using a 3D OP-OSEM algorithm with modelling of the point-spread-function [38 (link), 39 (link)], and attenuation corrected using the HRRT maximum a posteriori transmission reconstruction method (MAP-TR) [40 (link)]. Each image frame consisted of 207 planes of 256 × 256 voxels of 1.22 × 1.22 × 1.22 mm³.

The PET acquisition and quantification has been described in detail elsewhere [28 ]. Briefly, all patients were scanned with a High-resolution Research Tomography (HRRT) PET scanner (CTI/Siemens, Knoxville, TN, USA) for 120 min after an intravenous 20 s bolus injection of [¹¹C]-SB207145, and a 6 min transmission scan. The PET data was reconstructed into 38 time frames (6 × 5 s, 10 × 15 s, 4 × 30 s, 5 × 2 min, 5 × 5 min, and 8 × 10 min) and motion correction was performed with Air.5.2.5 [39 ], aligning each PET frame to the first 5 min frame (frame 26). All patients were MR-scanned using a Siemens 3-Tesla Prisma scanner, and T1 weighted MRI images were co-registered with the PET images to acquire anatomical information using SPM8. ROIs were automatically extracted using the pvelab software package [40 ] and delineated on each subject’s MRI. Correct co-registration of PET and MR images and ROI placement were visually quality checked in three planes by a trained investigator. Mean time activity curves for hemisphere weighted grey matter volumes were used in the kinetic modelling and the simplified reference tissue model with cerebellum (excluding vermis) as reference region [41 , 42 ] yielded non-displaceable binding potential (BP_ND) as outcome measure.

T1-weighted magnetic resonance (MR) images were acquired using a 3T Siemens Magnetom Trio or Verio MR scanner. All participants were examined using a HRRT PET scanner (Siemens Molecular Imaging, USA), with an approximate in-plane spatial resolution of 2mm [14 ]. A six-minute transmission scan was performed prior to each PET measurement to correct for signal attenuation. The radioligand [¹¹C]DASB, which binds selectively to 5-HTT, was prepared as described earlier [15 ]. In each PET experiment, a saline solution containing [¹¹C]DASB was injected into an antecubital vein as a bolus. The cannula was then flushed with saline. Emission data were acquired continuously for 90 min and subsequently binned into 36 consecutive time frames using the following frame definitions: six 10 s, three 20 s, six 30 s, five 1 min, five 2 min, eight 5 min, and three 10 min frames.