Biograph mct 64 system

Glucose metabolism was assessed by ¹⁸F-FDG PET/CT imaging using the Biograph mCT (64) system (Siemens Healthcare, Germany). As described [10 (link), 12 (link)], the patients fasted for at least 6 h but had free access to water until the start of the imaging process. Whole-body position was monitored 50 min after intravenous administration of FDG (3.7–4.1 MBq/kg) and lasted for about 15 min. The PET/CT images were acquired following the manufacturer’s protocol. The metabolic parameters of the ¹⁸F-FDG PET images were evaluated by two experienced nuclear medicine physicians who were blinded to the final clinical diagnosis. Briefly, a region of interest (ROI) was placed around the primary tumor, and then FDG uptake in the lesions was determined from the PET images to calculate the maximum and mean SUV (SUV_max and SUV_mean). SUV is defined as tissue concentration (Bq/g) × lean body mass (g)/injected dose (MBq)). A SUV_max threshold of 2.5 was used to define the metabolic tumor volume (MTV) (cm³), while total lesion glycolysis (TLG) is obtained by multiplying SUV_mean by MTV (TLG = ΣMTV × SUV_mean) [30 (link), 31 (link)]. In addition, the MTV and TLG were defined semi-automatically using an SUV-based platform as previously described [12 (link)].

PET/CT imaging of ¹⁸F-FDG was used to assess glucose metabolism. Referring to previous studies [27 (link), 29 (link)], patients fasted for 6–8 h before intravenous injection of ¹⁸F-FDG (3.7–4.1 MBq/kg). After 50 min of drug injection, PET/CT imaging was performed with Biograph mCT 64 system (Siemens Healthcare, Germany). Experienced nuclear medicine doctors draw the region of interest (ROI) around the tumor, and automatically calculate and record the maximum and mean standardized uptake value (SUVmax and SUVmean), total lesion glycolysis (TLG) and metabolic tumor volume (MTV) of each ROI through the system.