18f fdg

Clinical grade [¹⁸F]-FDG was obtained from the Johns Hopkins PET Center Radiopharmacy, supplied by PETNET Solutions (Siemens Healthcare, Malvern, PA, USA). Injectate was assayed using a sodium iodide CRC-15 dose calorimeter and a calibration factor of 439 (Capintec, Ramsey, NJ, USA). Standard [¹⁸F]-FDG uptake studies were preformed. Briefly, mice were anesthetized with isoflurane and injected intravenously via the retro-orbital sinus with 100 μCi of tracer diluted to a final volume of 150 μL in isotonic saline. Following a 2 h uptake period under continuous isoflurane anesthesia, animals were killed and tissues were collected. Tissue activity was assessed by gamma-counting, using an energy set ±50 keV from the 511 keV photopeak (Wizard^{2 (link)}, PerkinElmer, Waltham, MA). [¹⁸F]-FDG levels were normalized to the weight of resected tissue and expressed as the percent injected dose per gram tissue weight (%ID·g⁻¹).

All patients fasted for at least 6 h. Blood glucose concentration was confirmed to be <7.1 mM in each patient prior to administering ¹⁸F-FDG. ¹⁸F-FDG was purchased from Tianjin Atom High Science Isotopes Medicine Co., Ltd. The radiochemical purity of ¹⁸F-FDG was 98%, which was tested by the manufacturer. At 1 h post-intravenous injection of ¹⁸F-FDG [5.55 MBq/kg (0.15 mCi/kg)], whole-body PET/CT examination was performed using a Biograph mCT 64 system (Siemens Healthineers) in the supine position. CT images were acquired from the skull base to the upper thigh area for attenuation map and lesion localization (94–140 mAs, 120 kVp, 5-mm wide section). A 3.0-mm thick section was reconstructed for attenuation correction followed by subsequent image fusion. PET images of the same area were acquired following CT scans in 3-dimensional mode, with 6–7 bed positions. Images were reconstructed using an iterative algorithm and were transported to a dedicated workstation (syngoMMWP VE40A; Siemens Healthineers) and analyzed using the syngo TrueD software (TRUED_SYSLATEST_VE10A40; Siemens Healthineers).