Discovery ct750 hd scanner

The Discovery CT750HD scanner (GE Healthcare, Waukesha, WI, US) was used for scanning. The following scanning parameters in the GSI mode were used: tube voltage of 140 kV and 80 kV and 0.5-ms instantaneous switch; tube current, 0–600 mA automatic modulation; collimation thickness, 0.625 mm; rotation speed, 0.8 s; and helical pitch, 1.375. The total CT dose index volume used in this study was 18.28 mGy, 69.5% lower than the CT dose index volume of 59.89 mGy used for average conventional head scanning at our institution. An automated injector was used to inject an iodinated nonionic contrast agent (iopamidol 300; Bracco, Milan, Italy) at 2.8 mL/s and 1.5 mL/kg through the right ulnar vein. The scan’s venous phase delay time was 50 s.

A breath-hold CT scan was performed with patients immobilized using a Vac-Lok^™ Cushion in supine with their arms overhead. CT images were acquired during the end-expiratory phase with the breathing command. Multidetector CT was performed on a 64-slice GE Discovery CT 750HD scanner (GE Healthcare, Waukesha) with a slice thickness of 2.5 mm with no interslice gap.No intravenous contrast is used for these CT scans, and the whole procedure generally took about 20 min.

CT scans were performed on a Discovery CT750 HD scanner (HDCT, GE Healthcare, Milwaukee, WI, USA). All patients underwent abdomen contrast-enhanced spectral CT from the diaphragm to the edge of the kidney. The spectral CT scan protocol included helical pitch of 0.984:1, rotation speed of 0.5 s, and 50 cm Display Field of View (DFOV). The nonionic contrast media (ioversol, 320 mgl/ml) at the dose of 1.0 ml/kg was injected with a power injector at a rate of 3.0 ml/s through median cubital vein. Arterial phase scanning with an automatic tracking technique with automated scan-triggering software (SmartPrep, GE Healthcare, Milwaukee, WI, USA) started 8 s after the trigger threshold (100 HU) was reached at the level of the celiac trunk (He et al., 2014 (link)). The portal venous phase scanning and later delay phase scanning started for 30 and 120 s, respectively, after the beginning of the arterial phase scanning.

All patients underwent dual-phase contrast-enhanced CT scans using the Discovery CT750 HD scanner (GE Healthcare, Milwaukee, WI, USA) in gemstone spectral imaging (GSI) mode. The CT scan parameters were as follows: tube voltage, 80 kVp and 140 kVp instantaneous (< 0.5ms) switching; tube current, 375 mA; beam pitch, 0.984:1; rotation time, 0.7 s; matrix, 512×512; scanning field, 50 cm; slice thickness, 5mm; and slice spacing, 5mm. Scanning range was from lung tip to lung bottom. The non-ionic contrast agent iohexol (300 mgI/ml, Yangtze River Pharmaceutical Group, Jiangsu, China) was injected through the median cubital vein using a high-pressure syringe (XD8000, Ulrich, Germany) at a dose of 1.3–1.5 mL/kg and an injection rate of 3.5–4.0 ml/s. Arterial phase (AP) and venous phase (VP) scans were performed 30 s and 60 s after contrast injection using automatic tracking technology. Moreover, 60% ASiR-V iteration was used to reconstruct images at the end of the scan with a reconstructed slice thickness of 1.25 mm and reconstructed slice spacing of 1.25 mm.

All patients underwent non‐contrast thoracic CT scans on a 64‐slice GE Discovery CT750 HD scanner with a standardized protocol. The following imaging settings were used: tube voltage: 120 kVp; automated tube‐current modulation (TCM); slice thickness: 1.25 mm; pitch factor: 1.375; rotation time: 0.4 s; noise index: 14; and scan‐range encompassing the lung apices to the adrenal glands. The images were reconstructed with a filtered back projection (FBP) algorithm, a 512 × 512 matrix, 5‐mm slice thickness and interval, and a 36‐cm display FOV. The CT reconstructed image series was automatically transferred to a Picture Archiving and Communication System in Digital Imaging and Communications in Medicine (DICOM) format.

All patients underwent CT examinations (non-enhanced and dual-phasic contrast-enhanced scans) on a Discovery CT750HD scanner (GE Healthcare, WI). The non-enhanced scanning was performed first with the conventional helical mode at a tube voltage of 120kVp; tube current, 180mA; helical pitch, 1.375. A 80–100ml (1.35 ml/kg of body weight) nonionic iodinated contrast material (Iopamidol, 370 mg/ml; Shanghai Bracco Sine Phamaceutical Co. Ltd., China) was administrated at a rate of 4.0ml/s by using a power injector, and the dual-phasic enhancement scan delay times were 35 seconds at AP and 90 seconds at VP after the beginning of contrast medium injection. The contrast-enhanced scans were carried out with the dual energy spectral CT mode with fast tube voltage switching between 80kVp and 140kVp on adjacent views during a single rotation. The other DECT parameters were the following: tube rotation time, 0.6 seconds; tube current, 600mA; helical pitch, 1.375; field of view, 500mm; collimation, 40mm; and slice thickness and interval for axial images, 5mm/5mm. Two types of images were obtained from the reconstruction of DECT imaging automatically with GSI viewer software (GE Healthcare) for each patient: the iodine-based and water-based material decomposition images and a set of monochromatic images at energies ranging from 40 to 140keV.