PET Imaging of Tau Tracer APN-1607

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.