Biograph truepoint 64

[¹¹C]acetate was prepared according to a well-established method [27 (link)]. All PET/CT scans were obtained using combined PET/CT scanner (Siemens Biograph TruePoint 64). According to the routine protocol all patients were asked to fast for at least 6 h before the examination and then received an intra-venous injection of [¹¹C]acetate of 8 MBq/kg of body weight. After 20 min patients were scanned from thorax and abdomen. PET images were reconstructed using the TruX algorithm, with four iterations per 21 subsets, a 5-mm-slice thickness and a 168 × 168 matrix. Helical CT acquisitions were performed with 4 D care dose protocol and the following parameters: a tube current of 230 effective mAs, a tube voltage of 120 kVp, a collimation of 24 × 1.2 mm, a pitch of 0.813, and a scanning time of 0.5 s per rotation. For review, the CT images were reconstructed with a section thickness of 5 mm in 3-mm increments.
PET, non-enhanced CT and fused PET/CT images were generated and reviewed on the computer by a specialized physician, and co-registered images were displayed on special workstation system using Hybrid Viewer (HERMES Medical solutions, Stockholm, Sweden).

PSMA 11 PET/CT was performed from the vertex to the upper thighs using a 64-row, multidetector hybrid system (Biograph TruePoint 64; Siemens, Erlangen, Germany), with an axial FoV of 216 mm, a PET sensitivity of 7.6 cps/kBq, and a transaxial PET resolution of 4–5 mm (full-width at half-maximum). PET was performed 60 min after intravenous administration of 2 MBq/kg body weight ⁶⁸Ga-PSMA^HBED-CC conjugate 11 with 4 min per bed position, four iterations/21 subsets, slice thickness 5 mm and matrix size 168 × 168, using the point-spread function-based reconstruction algorithm TrueX. CT maps were used for PET attenuation correction. Venous-phase contrast-enhanced CT was performed after intravenous injection of 100 ml of a tri-iodinated, non-ionic contrast medium at a rate of 2 ml/s, with tube voltage 120 kV, tube current 230 mAs, collimation 24 × 1.2 mm, slice thickness 3 mm at a 2-mm increment, and matrix size 512 × 512.

Amyloid-PET scans were obtained with a Biograph Truepoint 64 PET/CT scanner (Siemens, Erlangen, Germany). All patients underwent PET scanning at rest after intravenous injection of 370 MBq. Amyloid-PET data were first qualitatively analysed by a trained physiologist using a binary method of interpretation for relating “positive” or “negative” scans to neuropathologically defined categories of Aβ plaque density. Structural MRI was also acquired, and FLAIR-weighted images and PET images were co-registered to individual volumetric T1-weighted images. After PET/MRI co-registration, ImcCalc of Statistical Parametric Mapping (SPM12, Wellcome Department of Cognitive Neurology, London, UK) was used to derive standardised uptake value (SUV) PET maps as SUV = AC/(radiotracer dose/BW). AC represents activity concentration in a given voxel [kBq/ml], radiotracer dose is the injected tracer dose corrected for residual activity in the syringe [MBq] and BW is the body weight [kg]. SUV maps were calculated in the grey matter (GM) of anterior cingulate gyrus, frontal lobe, parietal lobe, posterior cingulate gyrus, precuneus, temporal lobe, and of the average of these six regions (GM mean). The whole cerebellum was the reference region for the SUV relative ratio (SUVR). For the GM mean, we applied the validated threshold for amyloid-PET SUVR (1.11) [24 (link), 25 (link)].

All patients fasted for 6 h before undergoing ¹⁸F-FDG-PET/CT, which involved the injection of 4.44 MBq/kg of ¹⁸F-FDG. In all cases, the fasting serum glucose level was below 180 mg/dL. The studies were performed in a 64-slice PET/CT scanner (Biograph TruePoint 64; Siemens Medical Solutions, Knoxville, TN, USA) 60 min after radiotracer injection. The CT parameters included 5 mm axial reconstruction, with a tube voltage of 120 kV or automatic tube voltage selection (CARE Dose 4D; Siemens Healthcare, Forchheim, Germany). The PET images were acquired from the head to upper thighs in three-dimensional mode with 90 s/bed position, without contrast administration.