Biograph mmr system

Participants underwent a PET-MRI acquisition on the Siemens mMR Biograph system. Because the pilot study group scans showed that [¹⁸F]F13640 activity curves slowly continued to vary even at later time points, suggesting that there may be further changes beyond 90 min. A PET-MRI acquisition of almost 4 h was tested to observe kinetics for a longer period. For the comfort of the subjects, the acquisition was carried out in two parts. In part 1 (PET1), list-mode PET data were acquired for 90 min directly after the injection of [¹⁸F]F13640 (150 MBq + 1 MBq/kg ± 10%) (PET1, [0; 90] min. post injection). Subjects were then taken out of the camera for a break. One hour later, for part 2 (PET2), subjects had a second PET-MRI scan for 75 min (PET2; [150; 225] min. post injection). Participants performed this PET-MRI protocol twice (test and retest sessions) 1 to 9 weeks apart.
During PET1, a 3D T1 MPRAGE MRI was acquired in sagittal orientation, with a matrix size of 256 × 256 × 176 and a voxel size of 1 mm iso. TR/TE was 3300/2.45 ms, TI 1100 ms, and flip angle 8°. A quicker T1 MPRAGE MRI was acquired at the beginning of PET2 to accurately register data from the two sessions (sagittal acquisition, matrix size 256 × 256 × 176, voxel size 1 mm iso, TR/TE 1800/2.34 ms, TI = 850 ms, flip angle 8).

[¹¹C]yohimbine was synthesized as previously described [29 (link)]. The radiochemical purities of syntheses used for the study were greater than 95%, with corresponding molar activities of 70 ± 29 GBq/μmol at the end of synthesis. All subjects received an intravenous bolus injection of 370 MBq ± 10% of [¹¹C]yohimbine. List-mode PET data were acquired, during the 90 min from the injection of the tracer, simultaneously with 3T MRI data (Dixon T1, anatomic MPRAGE T1) on a Siemens mMR Biograph system.

All PET-MRI scans were performed with a Biograph mMR system (Siemens, Erlangen, Germany), which consists of an MRI-compatible PET detector integrated with a 3.0-T whole-body MRI scanner. The PET component provided an axial field of view (FoV) of approximately 26 cm and a transverse FoV of 59 cm with a sensitivity of 13.2 cps/kBq, which was obtained utilizing a three-dimensional (3D) acquisition technique. Patients were administered an intravenous injection of 2 MBq/kg body weight [⁶⁸Ga]Ga-PSMA-11 60 min prior to the start of the PET-MRI acquisition. A partial body PET scan was obtained from skull base to thighs with four bed positions (5 min sinogram mode each). PET images were reconstructed using 3 iterations and 21 subsets. Dixon-VIBE sequences were used for attenuation correction based on MRI, which included in-phase, opposed-phase, and fat-saturated as well as water-saturated images. For patients with BCR and mCRPC, the exact MRI sequences within these integrated PET-MRI scans were mentioned in a previously published study by Grubmüller et al. [16 (link)]. For patients with primary PCa, the detailed MRI sequences were reported in another previously published study [17 (link)].