Biograph hi rez

All patients underwent [18F]FDG-PET scans performed with PET cameras manufactured by GE Healthcare medical systems (GE Healthcare, Chicago, IL): GE Discovery PET/CT 690 (PD cohort: PD-LDR and PD-HDR, 256×256 matrix with a voxel size of 1.95 mm) and STE scanner (DLB, MSA and iRBD, 128×128 matrix with a pixel size of 1.95 mm). The [18F]FDG PET scans of 112 HC subjects were obtained using either a GE Discovery ST, GE Discovery STE, Siemens Biograph Hi-rez or Siemens ECAT EXACT HR + PET scanner (see (Caminiti et al., 2021 (link), Presotto et al., 2017 (link))). The [18F]FDG-PET acquisition procedures fulfilled the European Association of Nuclear Medicine guidelines (Varrone et al., 2009 (link)). Before radiopharmaceutical injection, subjects fasted for at least 6 h to ensure that the measured blood glucose level was <120 mg/dL. Subjects underwent a 3D PET scan (time interval between injection and scan start ranged from 30 to 45 min; scan duration ranged from 10 to 15 min) after the injection of [18F]FDG (185–250 MBq: usually, 5–8 mCi via a venous cannula). Reconstruction of all images was performed using an ordered subset-expectation maximisation algorithm (OSEM, 28 subsets, 2 iterations, 2-mm post-filter). For all clinical groups, CT scans were used for attenuation correction.

Eleven PET/CT scanners were used for the robustness study: n. 2 Discovery ST (S1, S2) [17 (link)], n. 1 Discovery STE (S3) [18 (link)], n. 2 Discovery 600 (S4, S5) [19 (link)], and n. 1 Discovery 690 (S6) [20 (link)] (GE Healthcare, Milwaukee, WI), n. 1 Biograph HI-REZ (S7) [21 (link)] and n. 1 Biograph TRUEV (S8) [22 (link)] (SIEMENS Medical Solutions, Knoxville, TN), n. 1 Gemini XL (S9) and n. 2 Gemini TF (S10, S11) [23 (link)] (Philips Medical Systems, Cleveland, OH). The technical characteristics and physical performances of the PET/CT scanners were derived from factory data and/or previous publications and are reported in Table 1.