Ge discovery ct750 hd scanner

Computed tomography scans were obtained for all patients included in the study with the GE Discovery CT 750 HD scanner, USA (GE Healthcare, Milwaukee, USA) using the following parameters: 120 kV tube voltage, 264 mAs tube current, slice thickness of 5 mm, field of view (FOV) of 240 × 240, and matrix of 512 × 512.
The hyperdense middle cerebral artery sign (HMCAS) can be defined qualitatively as any artery that appears denser than adjacent or equivalent contralateral arteries (6 (link), 7 (link)). However, quantitative definitions [>43 Hounsfield units (HU) or >1.2-fold the density of a normal contralateral vessel] have also been proposed (8 (link), 9 (link)). Other signs include assessment of the difference in density of obscuration of the lentiform nucleus and insular ribbon sign between the affected and healthy side (10 (link)). All image variables were measured independently by two neuroradiologists with extensive experience who were blinded to symptoms or side effects. Cases of disagreement between two observers were settled by consensus (Figure 1).
MCI was defined as infarction area ≥20 cm² or lesions involving more than two lobes (11 (link), 12 (link)).

After fasting for 8 h, patients were asked to consume 1000 mL of warm water and then injected with 20 mg of scopolamine (Specifications: 10 mg/mL; Hangzhou Minsheng Pharmaceutical Group Co., Ltd. Hangzhou, China) 10 min prior to examination. Patients were placed in the supine position, and scanned on GE Discovery CT750 HD scanner (GE Healthcare, Milwaukee, WI, USA) with gemstone spectral imaging (GSI) mode. Dual-energy CT images were acquired using a single x-ray source switches rapidly between 80 kVp and 140 kVp at less than 5 millisecond speed. The other acquisition parameters were as follows: 5 mm slice thickness, 40 mm detector coverage, 0.984 helical pitch, 630 mA tube current, 0.6 s rotation time, 512 × 512 matrix, and 40 × 40 cm field of view. AP and PP contrast-enhanced CT scans were performed with 40 and 70 s delays, respectively, after intravenous injection of 85–110 mL (1.5 mL per kg of body weight) iodinated contrast material (Ultravist 370, Bayer Schering Pharma, Berlin, Germany) at a rate of 3.0 ml/s through pump injector (Ulrich REF XD 2060-Touch, Ulrich Medical, Ulm, Germany). Contrast-enhanced CT images were reconstructed by using a standard kernel and 2.5 mm section thickness. The value of CT dose index volume (CTDIvol) for dual energy spectral mode in the abdomen was 23.84 mGy.

All patients underwent dual-energy CT examinations in gemstone spectral imaging (GSI) mode (GE Discovery CT750 HD scanner; GE Healthcare, Princeton, NJ, USA). DECT scans were from the skull base to the aortic arch level and in the head-foot direction. The DECT scan parameters were as follows: 64×0.625-mm detector collimation; 0.8-sec tube rotation time; 0.984 pitch; 1.25-mm-thick sections; 1.5-mm-thick section increments; rapid switching of high (140 kVp) and low (80 kVp) tube voltages; 360-mA tube current. For contrast-enhanced scans, patients were injected with 1.6 mL/kg of nonionic iodinated contrast medium (300 mg I/mL) by a pump injector at a rate of 3.5 mL/s into the antecubital vein. Images of arterial and venous phases were performed after 25- and 55-sec delays, respectively.
Iodine maps of both arterial and venous phases at a 1.5-mm slice thickness can be autogenerated by DECT.

NCECT examinations were conducted in the supine position with the arms up after deep inspiration. The CT data were acquired from one of the two scanners: Somatom Definition flash (Siemens Medical Solutions, Germany) and GE Discovery CT750 HD scanner (GE Healthcare, USA). The scanning parameters are detailed in Supplementary Table S1. Subsequently, the CECT was performed at 35 to 60s after injecting a dose of 80–100 ml nonionic IV contrast material (350 mg/ml, Omnipaque, GE Healthcare) mixed with isotonic saline into the ulnar vein using a high-pressure syringe at a rate of 3.0–4.0 ml/s.
The clinical and radiographic features were reviewed by two radiologists (H.W. and D.B.M.) with more than 10 years of experience in chest CT interpretation in a blinded fashion. We used the electronic caliper in our picture archiving and communication system to measure the maximum diameter of PSNs (nodule_max) and the maximum diameter of the corresponding solid component (solid_max). The consolidation-to-tumor ratio (CTR) was subsequently determined by dividing the solid_max by the nodule_max. Any discrepancies in describing the radiographic features were settled by consensus reading.

CT examinations were performed with one of the two scanners: GE Discovery CT750 HD scanner (GE Healthcare, USA) and Somatom Definition flash (Siemens Medical Solutions). All patients were asked to hold the breath at the end of inspiration. NCECT images were acquired in the supine position. The details of the scanning parameters were as follows: tube voltage 120kVp, tube current 120-200 mA, collimation 0.6 or 0.625 mm*64, rotation time 0.33 or 0.5 s/rot, SFOV 50 cm, slice thickness of reconstruction 1or 1.25 mm, slice interval of reconstruction 1or 1.25 mm, reconstruction algorithm STND and Medium sharp, matrix 512 × 512. After NCECT scanning, a dose of 80–100 ml non-ionic IV contrast material (350 mg iodine/ ml, Optiray, Mallinckrodt) was injected into the antecubital vein at a rate of 3.0–4.0 ml/s using a powerful automated injector. The CECT scanning was performed at 35 to 60 s after the injection.