PET/CT Imaging Protocol for Tau Deposition

The day prior to the imaging study, water consumption was encouraged to induce more rapid clearance of the radioisotope. Subjects were injected with 370 ± 37 MBq of ¹⁸F-AV-1451 intravenously. Imaging was delayed for 80–100 min following injection to allow for uptake of the radiotracer. PET/CT scans were then acquired on the GE Discovery RX or Discovery 690XT (General Electric Healthcare; Waukesha, WI, USA) cameras. CT images were reconstructed in a transaxial slice orientation with a slice thickness of 3.75 and interval of 3.27 or 1.96 mm depending on the scanner. Forty-seven or seventy-nine slices were obtained again dependent on the scanner and interval used. For CT imaging, kVp was 120 and mA was 35–40. On PET, four frames of 5 min each were obtained to correct for patient motion and were summed. A 3D OSEM iterative algorithm was used for reconstruction and a 5.0 mm post-filter was applied. Attenuation correction was measured using the CT obtained prior to PET. MRIs were performed at 3 T using an eight-channel phased array coil on all participants. MRI methods have been previously described [37 (link)].