Biograph truepoint

All patients underwent whole-body ¹⁸F-FDG PET/CT scans using a Siemens Biograph TruePoint PET/CT scanner (Siemens AG, Munich, Germany). After 6 h of fasting, PET/CT scan was carried out at 50~60 min after intravenous administration of 3.70~5.55 MBq/kg of ¹⁸F-FDG, with radiochemical purity >95% (Nanjing Jiangyuan Andike Positron Research and Development Co., Ltd., Nanjing, Jiangsu, China). Blood glucose level was monitored before scanning to ensure that the mentioned level was less than 11.0 mmol/l. The CT parameters were as follows: 120 kV, 80 mA, and PET acquisition was performed at 1 min per bed position for body and 2.5 min per bed position for head. All PET/CT images were interpreted by two experienced nuclear physicians retrospectively using a standard workstation (Syngo MMWP; Siemens AG, Munich, Germany). Focal or diffuse FDG uptake above background in a location mismatched with normal anatomy or physiology was interpreted as abnormal and indicative of a lymphoma lesion. The maximum standardized uptake values (SUV_max) were determined on PET scans.

The baseline ¹⁸F-FDG PET/CT studies performed at our institution were
acquired with the protocol described below. All of the baseline scans were
performed within the last 30 days prior to percutaneous ablation.
Patients were required to fast for 6 h prior to the injection of
¹⁸F-FDG, in order to achieve a blood glucose level below 140 mg/dL.
All patients received ¹⁸F-FDG at a dose of 7.77 MBq/kg (0.21 mCi/kg)
while resting in a dark, quiet room.
Whole-body PET/CT scans were acquired 60 min after ¹⁸F-FDG injection.
The images were acquired on a high-resolution imaging platform (Biograph
TruePoint; Siemens Medical Solutions, Knoxville, TN, USA) with lutetium
oxyorthosilicate crystal detectors, 16-slice CT detectors, and a spatial
resolution of 4.2 mm. The image post-processing was performed with Syngo
MultiModality Workplace software (Siemens Medical Solutions). The PET images
were acquired after the CT images (5 min per bed position). Images were
submitted to iterative reconstruction in the axial, coronal, and sagittal
planes, CT being used for attenuation correction. The maximum SUV
(SUV_max), was calculated for each lesion. Two experienced nuclear
medicine physicians and a radiologist analyzed the images. Discordant findings
were reviewed by a third experienced nuclear medicine physician.

All subjects underwent PET/CT scans using 18F-FDG within 2 weeks before surgery with the protocol of PET/CT scanning used at our institution. Before imaging, patients fasted for 6 h and their blood glucose levels were as tested, below 7 mmol/L. The recommended intravenously injected dosage for 18F-FDG was 5.55 MBq/kg and a standard 60 min post-injection rest allowed before PET/CT scanning. FDG-PET/CT scans were performed on a PET/CT scanner (Biograph Truepoint, Siemens). The data acquisition procedures were as follows: The scan covered the trunk from skull base to midthigh. Attenuation correction was performed using a low-dose helical CT protocol (90 mAs, 110 kV, 0.9 pitch) under normal breathing. Immediately after CT scanning, a PET emission scan that covered the identical transverse field of view was obtained. The PET images, including axial, sagittal and coronal images, were reconstructed using the true X method, and postfiltered with a 5.0 mm full width at half maximum (FWHM) in a matrix of 168. SUV = (activity/unit volume)/(injected dose/total body weight). The maximum SUV (SUV max) was defined as the peak SUV on one pixel with the highest counts within region of interest. Images of PET/CT were reviewed by two nuclear medicine doctors experienced in PET/CT image reading.

All patients fasted for at least 6 h before the PET/CT study. Scanning began 60 minutes after the intravenous injection of ¹⁸F-FDG (370–555 MBq). None of the patients had a blood glucose level greater than 130 mg/dL before the injection. No intravenous contrast agent was administered. Studies were acquired on combined PET/CT inline systems, either Biograph Duo or Biograph TruePoint (Siemens Medical Solutions, Knoxville, TN, USA). The first scan, a whole-body image from the orbitomeatal line to the upper thigh, was performed 1 h after ¹⁸F-FDG injection. Six to eight bed positions were used and the acquisition time was 2 min per bed position. CT began at the orbitomeatal line and progressed to the proximal thigh (120 kV, 50 mAs, and 5 mm slice thickness; 130 kV, 80 mAs, and 5 mm slice thickness) and was followed by a PET over the same body region. CT data were used for attenuation correction and images were reconstructed using a standard ordered-subset expectation maximization algorithm (OSEM two iterations, eight subsets). Axial spatial resolution was 6.5 or 4.5 mm at the center field of view. All PET/CT images were reviewed with fusion software (syngo; Siemens Medical Solutions, Knoxville, TN, USA) that provided multiplanar reformatted images and displayed PET images with attenuation correction, CT images, and PET/CT fusion images.