Biograph mct flow system

The radiosynthesis of [¹⁸F]PM‐PBB3 and [¹¹C]PiB is described in the Supporting Information (eMethods in Appendix S1).³⁶, ³⁷ PET scans were performed with a Biograph mCT flow system (Siemens Healthcare; matrix size 200 × 200 × 109; voxel size [mm] 2 × 2 × 2 for [¹⁸F]PM‐PBB3 and [¹¹C]PiB ligands) and a discovery MI (GE Medical Systems; matrix size 128 × 128 × 89; voxel size [mm] 2 × 2 × 2.8 for [¹¹C]PiB ligand). PET images were reconstructed using a filtered back‐projection algorithm with a Hanning filter (6.0 mm full width at half maximum). Detailed PET scanning protocols were described previously.¹², ³⁸ Each participant received 90‐ to 110‐minute PET scans (frames: 4 × 5 or 2 × 10 minutes) after intravenous injection of [¹⁸F]PM‐PBB3 (186 ± 8.4 MBq) and 50‐ to 70‐minute PET scans (frames: 4 × 5) after intravenous injection of [¹¹C]PiB (526 ± 72.0 MBq) within 3 months.

After intravenous rapid bolus injection of [¹¹C]HMS011, three-dimensional dynamic images were acquired in a PET camera for 120 min with 39 frames of increasing duration from 10 s to 5 min (10 s × 6, 20 s × 3, 1 min × 5, 3 min × 4, and 5 min × 20). All PET studies were performed with a Biograph mCT flow system (Siemens Healthcare, Erlangen, Germany), which provides 109 sections with an axial field of view of 16.2 cm. The intrinsic spatial resolution was 5.9 mm in-plane and 5.5 mm full-width at half-maximum axially. Images were reconstructed using a filtered back projection algorithm with a Hanning filter (6.0 mm full-width at half-maximum). All PET images were corrected for attenuation based on CT images, for random using the delayed coincidence counting method, and for scatter using the single-scatter simulation method. A head fixation device was used to minimize the subject’s head movement during the PET measurements.
MR images were acquired with a 3-T scanner, MAGNETOM Verio (Siemens Healthcare, Erlangen, Germany). Three-dimensional volumetric acquisition of a T1-weighted gradient echo sequence produced a gapless series of thin sagittal sections (TE = 1.95 ms, TR = 2300 ms, TI = 900 ms, flip angle = 9°, acquisition matrix = 256 × 256 × 250, voxel size = 1 × 1 × 1 mm). None of the subjects exhibited apparent structural abnormalities in MR images.