Mct40

All patients underwent PET–CT using integrated PET–CT scanners (Biograph Truepoint or mCT40, Siemens Healthineers; Gemini TF scanner, Philips Healthcare; Discovery STE, General Electric Healthcare). Patients fasted for at least 6 h, and FDG (5.18 MBq/kg) was administered intravenously. Images were acquired approximately 60 min after injection. Patients were examined in the supine position with the arm down. A CT scan (40 mA and 120 kVp) was performed for attenuation correction without contrast enhancement, and PET images were acquired from the skull base to the toe. The CT images were reconstructed using a 512 × 512 matrix in combination with a 50-cm field of view and a 3-mm slice thickness.

Pretreatment whole-body PET/CT was acquired on a Siemens mCT40 PET/CT scanner (Siemens Healthineers, Erlangen, Germany). Patients were positioned supine with images obtained from the top of the skull to the upper thighs. Iodinated oral contrast material was administered for bowel opacification; no intravenous iodinated contrast material was used. Patients were injected with 300–400 MBq (4–5 MBq/kg) of ¹⁸Fluoride-Fluorodeoxyglucose (¹⁸F-FDG) after having fasted for 6 h, and PET/CT scanning was performed after approximately 60 min. Overall, five to nine bed positions were obtained, depending on patient height, with an acquisition time of 2–3 min per bed position. The CT settings were as follows: 120 kV; 3.0 mm slice width; 2.0 mm collimation; 0.8 s rotation time; and 8.4 mm feed/rotation. A PET emission scan using time of flight with scatter correction was obtained, covering the identical transverse field of view. The PET parameters were as follows: image size: 2.6 pixels; slice: 3.27; and a 5-mm full width at half-maximum (FWHM) gaussian filter type. Overall, patient data has been acquired as published by our group previously (27 (link)).

PET was usually performed within 1 week prior to starting the first cycle of chemotherapy using integrated PET/CT scanners (Gemini, Philips, Cleveland, OH, USA; Biograph True or mCT40, Siemens, Hoffmann Estates, IL, USA). After fasting for at least 8 hours, ¹⁸F-FDG (5.18 MBq/kg) was injected, and images were acquired 1 hour later. PET scans were then obtained from the mid-thigh to the skull base, and images were reconstructed using the ordered subset expectation maximum iterative reconstruction algorithm. The SUV was calculated as tissue concentration of radioactivity (kBq/mL) divided by injected dose per weight (kBq/g). To measure the SUVmax of the circular region of interest (ROI), which was defined as the peak SUV in the pixel with the highest count within the ROI, and SUVmax was automatically measured using an analysis software package (Syngo.via, Siemens).