Biograph 6 pet ct scanner

After histopathological confirmation of prostate cancer, all patients underwent ⁶⁸Ga-PSMA-11-PET/CT for further staging. One hour (±10 min) after intravenous injection of ⁶⁸Ga-PSMA-11, synthesized as previously described^{19 (link)}, scans were performed on a Biograph 6 PET/CT Scanner (Siemens, Erlangen, Germany). Initially, a CT scan (130 keV, 80 mAs; CareDose) without contrast medium was acquired. Corrected for dead time, scatter and decay, statistic emission scans were performed from the vertex to the proximal leg, requiring eight bed positions with 3 min per bed position. Image reconstruction was performed using CT-based attenuation correction with the ordered subset expectation maximization algorithm including four iterations with eight subsets and Gaussian filtering to an in-plane spatial resolution of 5 mm at full-width at half-maximum. Circular regions of interest were drawn in transaxial slices into areas with increased uptake and automatically adapted to a three-dimensional volume of interest with e.soft software (Siemens, Erlangen, Germany) at a 50% isocontour to calculate standardized uptake values (SUVs).

Patients were advised to limit their physical activity on the day prior to the examination. Patients fasted for a minimum of four hours prior to imaging. Patients' blood glucose levels were measured before FDG injection. FDG was injected intravenously at a mean dose of 370 MBq/70 kg body weight. Patients were also kept as still as possible in a quiet room during FDG injection and during the postinjection waiting period of 60 minutes and advised to be quiet. Biograph 6 PET/CT scanner (Siemens Medical Systems, Knoxville, TN) was used for the imaging procedure. First CT scan and then PET scan were performed. Although they vary according to the height of the patients, CT and PET images were obtained at an average of seven bed positions (from vertex to proximal thigh). Imaging began with the head. The arms were placed down below the navel during the imaging of head and neck tumors and above the head during the imaging of other types of tumors. The CT component of the integrated scanner was 6-slice. Energy level of the CT imaging was 130 KV and 80 mAs. Slice thickness was set to 6 mm. The detector crystal in the PET scanner was LSO. PET emission scans were acquired for 3 min/bed position in 128 × 128 matrix. TrueD software program was used to evaluate the images.

⁶⁸Gallium was eluted from a ⁶⁸Ge/⁶⁸Ga radionuclide generator (GalliaPharm, Eckert & Ziegler Radiopharma, Berlin, Germany), and the radiolabeling of PSMA-11 (ABX GmbH, Radeberg, Germany) followed an established protocol [13 (link)]. In the control group, the mean injected activity was 131 ± 18 MBq for the first scan (PET 1) and 134 ± 23 MBq for the second scan (PET 2), yielding no significant differences in comparison (p = 0.372). Image acquisition was initiated 63 ± 14 min (PET 1) and 63 ± 16 min (PET 2) after injection (p = 0.913), respectively. The median time interval between PET 1 and PET 2 was 12 (IQR 8–20) months. In the RLT group, baseline PET/CT (pre RLT PET) was performed with a mean injected activity of 131 ± 25 MBq;, the mean activity for post-RLT scans (post RLT PET) was 130 ± 26 MBq (p = 0.883). Injection-to-acquisition time was 64 ± 16 (pre RLT PET) and 66 ± 18 min (post RLT PET) (p = 0.636), respectively. Median time from the last treatment cycle to post RLT PET was 8 (IQR 6–12) weeks. Whole-body images were acquired from vertex to mid-thigh. A Biograph 6 PET/CT scanner (Siemens, Erlangen, Germany) was used, with decay, scatter, and attenuation correction performed in accordance with the joint EANM and SNMMI consensus statement [14 (link)].

Radiolabeling of PSMA-11 followed an established protocol [13 (link)]. ⁶⁸Gallium was obtained from a ⁶⁸Ge/⁶⁸Ga radionuclide generator (GalliaPharm, Eckert & Ziegler Radiopharma, Berlin, Germany). [⁶⁸Ga]Ga-PSMA-11 was administered by intravenous injection and target activity per patient was 1.8–2.5 MBq/kg body weight. Whole-body images (vertex to mid-thigh) were acquired 61 ± 12 min after tracer injection and PET acquisition time was 4 min per bed position. CT data were acquired for attenuation correction and anatomical localization using an X-ray tube voltage of 130 kV with a modulated tube current (CARE Dose 4D, Siemens, Erlangen, Germany). Acquisitions were carried out on a Biograph 6 PET/CT scanner (Siemens, Erlangen, Germany), with decay, scatter, and attenuation correction performed in accordance with the procedure guidelines set out by the joint EANM and SNMMI consensus statement [14 (link)].