PET/CT scans were acquired after a single FDG injection. Patients fasted for 6 hours before the 18F-FDG injection (serum glucose level <180 mg/dL). FDG dose was corrected for body mass index at all centers. The scan was obtained from the subcranial region to the upper thigh (torso) 60 to 90 minutes after the injection. A low-dose CT acquisition without contrast enhancement (NE CT) was initiated first, followed by PET acquisition. Then, the CE CT scans were collected. Iterative reconstruction was done using ordered-subset expectation maximization software. The attenuation was corrected by NE CT. NE PET/CT was not performed at one institution, and CE PET/CT was used for attenuation correction in these patients (n=14).
The PET/CT machines used in this study were as follows: the Biograph TruePoint 40 PET/CT scanner (Siemens Medical Solutions, Knoxville, TN, USA) or the Biograph 16 PET/CT scanner (Siemens Medical Solutions), the Discovery ST PET/CT instrument (GE Medical Systems, Milwaukee, WI, USA), the Discovery ST PET/CT instrument (GE Medical Systems), the Discovery VCT PET/CT instrument (GE Medical Systems), and the Gemini TF (Philips-ADAC Medical Systems, Cleveland, OH, USA). The workstations used for reconstruction were the Syngo multimodality workplace, Exeleris Advanced Workstation 4.4 (GE Medical Systems).
The PET/CT machines used in this study were as follows: the Biograph TruePoint 40 PET/CT scanner (Siemens Medical Solutions, Knoxville, TN, USA) or the Biograph 16 PET/CT scanner (Siemens Medical Solutions), the Discovery ST PET/CT instrument (GE Medical Systems, Milwaukee, WI, USA), the Discovery ST PET/CT instrument (GE Medical Systems), the Discovery VCT PET/CT instrument (GE Medical Systems), and the Gemini TF (Philips-ADAC Medical Systems, Cleveland, OH, USA). The workstations used for reconstruction were the Syngo multimodality workplace, Exeleris Advanced Workstation 4.4 (GE Medical Systems).