Stargate scanner

¹⁸F-THK5351 and ¹¹C-Pittsburgh compound B (PiB) were manufactured at the Cyclotron and Radioisotope Center of Tohoku University using a semiautomated system developed in-house. The injectable solutions of ¹⁸F-THK5351 and ¹¹C-PiB were obtained with a radiochemical purity of >95% and specific activity of 357 ± 270 and 240 ± 48 GBq/μmol. PET imaging was performed using an Eminence STARGATE scanner (Shimadzu, Kyoto, Japan). After rapidly injecting 185-MBq ¹⁸F-THK5351 or 296-MBq ¹¹C-PiB, PET images were obtained for 20 min (4 scans × 300 s) from 40 to 60 min or 50–70 min postinjection and used for further analysis. In addition, a 3D volumetric acquisition of a T1-weighted gradient echo sequence produced a gapless series of thin axial sections using a spoiled gradient recall sequence (echo time/repetition time, 3.4/7.2 ms; flip angle, 9°; acquisition matrix, 240 × 256; 1 excitation; field of view, 25.6 cm; slice thickness, 0.8 mm) of a Vantage Titan™ 3T scanner (Canon Medical Systems, Otawara, Japan).

PET imaging was performed using an Eminence STARGATE scanner (Shimadzu, Kyoto, Japan). After injecting 185 MBq of [¹⁸F]THK-5117 or 296 MBq of [¹¹C]PiB, dynamic PET images were obtained for 90 min or 70 min, respectively. MR scans were performed in all subjects. T1-weighted and T2-weighted MR images were obtained using a SIGNA 1.5-Tesla machine (General Electric, Milwaukee, WI). [¹⁸F]THK-5117 PET images from 60 to 80 min post-injection were used for the following analysis.