Signa tof pet mr

Nervous system-related drugs were stopped for more than 12 h before scanning. The precursor of APN-1607 was obtained from APRINOIA Therapeutics (Suzhou, China). According to the method described before (Weng et al., 2020 (link)), ¹⁸F-APN-1607 was prepared on an ¹⁸F-multifunction synthesizer (GE TRACERlab FxFn), and the radiochemical purity was >95%. ¹⁸F-APN-1607 was administrated intravenously (3.7–5.5 MBq/kg) under the green light-emitting diode light (510 nm) illumination. Resting for 60 min, the PET scanning was completed with hybrid PET/MR (3.0 T, SIGNA TOF-PET/MR, GE Healthcare). During 20 min PET acquisition, the 3D T1-weighted imaging [three-dimensional gradient echo sequence, flip angle = 12°, time of echo (TE)/time of repetition (TR) = 2.6/6.9 ms, bandwidth = 50 kHz, FOV = 24 cm × 24 cm, matrix = 384 × 384] was obtained simultaneously. The PET data were reconstructed using the ordered subsets expectation maximum (OSEM) algorithm (FOV = 30 cm × 30 cm, matrix = 192 × 192, filter cutoff = 3.0 mm, subsets = 28, iterations = 3), and the time-of-flight (TOF) technique was utilized for the reconstruction. The PET attenuation correction for PET/MR was atlas-based MRI attenuation correction, combined with Dixon water-fat separation methods.

After PET/CT acquisition, all patients underwent a neck PET/MR (3.0 T, signa TOF-PET/MR, GE Healthcare, Milwaukee, WI, USA) scan around 120 min after ¹⁸F-FDG injection. Head and neck coil and field of view (FOV) were used for PET/MR scanning. The scanning sequence included axial fast spin echo T1 weighted imaging (FSE T1WI), axial, sagittal, and coronal FSE T2WI, and finally axial DWI. PET scanning used 3D acquisition, with about 15 min per bed. The scanning parameters were T1WI (turn angle = 142°, echo time [TE]/repeat time [TR] = 13.2/640 ms, bandwidth = 41.67 KHz, FOV = 24 cm × 24 cm, matrix = 256 × 192), T2WI (turn angle = 142°, echo time [TE]/repeat time [TR] = 161/3054 ms, bandwidth = 50 KHz, FOV = 22 cm × 22 cm, matrix = 288 × 288), DWI (echo time [TE]/repeat time [TR] = 191/2500 ms, bandwidth = 250 KHz, FOV = 24 cm × 24 cm, matrix = 96 × 96, b = 600). The time of flight (TOF) technique and OSEM algorithm were used to reconstruct the PET data with the following parameters: FOV = 30 cm × 30 cm, matrix = 192 × 192, filter cutoff = 3.0 mm, subset = 28, iteration = 3. PET attenuation correction was based on atlas MR attenuation correction combined with the Dixon water–fat separation method.

All patients underwent ¹⁸FDG-PET and MRI brain imaging simultaneously in a hybrid PET/MR scanner (3.0 T, SIGNA TOF-PET/MR, GE Healthcare). The ¹⁸F-FDG was produced in our center by a Minitrace cyclotron (GE Healthcare, USA) and automatic synthesizer (PAT Biotechnology Company, Beijing, China). The radiochemical purity was > 95%.
All participants fasted for at least 6 h and stopped any drugs that could affect brain glucose metabolism for at least 12 h before the ¹⁸F-FDG injection. The intravenously injected dose was 0.1 mCi/kg (3.7 MBq/kg) after ensuring the blood glucose level was ≤ 200 mg/dL. The scan began 40 min post ¹⁸F-FDG injection, during which the subject rested in a quiet and dimly lit room. The total scanning time for PET was 15 min, and the 3D T₁WI (three-dimensional gradient echo sequence, flip angle = 12°, time of echo [TE]/time of repetition [TR] = 2.6/6.9 ms, bandwidth = 50 KHz, FOV = 24 cm × 24 cm, matrix = 384 × 384) sequence was simultaneously acquired.
The PET data were reconstructed using the ordered subsets expectation maximum (OSEM) algorithm with TOF technique. The parameters were as follows: FOV = 30 cm × 30 cm, matrix = 192 × 192, filter cutoff = 3.0 mm, subsets = 28, iterations = 3. The PET attenuation correction was atlas-based MRI attenuation correction, combined with Dixon water-fat separation methods [27 (link)].