Because the CT data in this study were collected over a long period, various CT techniques were used. CT scans were obtained using 4-channel (Lightspeed Qx/i, GE Healthcare, Milwaukee, WI, USA; n = 2), 16-channel (Lightspeed 16, GE Healthcare or Sensation 16, Siemens Healthineers, Erlangen, Germany; n = 1611), 64-channel (Definition AS, Siemens Healthineers; n = 564), and 128-channel (Definition Flash, Siemens Healthineers; n = 41) scanners. Non-enhanced CT images were obtained at beam collimations of 4 × 2.5 mm (Lightspeed Qx/i), 8 × 2.5 mm (Lightspeed 16), 16 × 1.5 mm (Sensation 16), 24 × 1.2 mm (Definition AS), and 64 × 0.6 mm (Definition Flash); at a spiral pitch of 1 to 1.5; at tube voltages of 120 kVp (n = 1672) and 100 kVp (n = 546); and at tube currents of 200 mAs (GE scanners) or variable mAs (Siemens scanners) with an automatic exposure control (Care Dose 4D, Siemens Healthineers; maximum effective dose, 200 mAs). Axial images were reconstructed at section thicknesses of 3 mm (n = 45) and 5 mm (n = 2173), with no gaps. The mean interval between CT and liver biopsy was 0.4 ± 0.7 days (range, 0–3 days), with 1710 (74.8%) subjects undergoing CT scanning and liver biopsy on the same day.
Definition as
Manufactured by GE Healthcare
Sourced in United States, Japan
Definition AS is a laboratory equipment product by GE Healthcare. It is used for spectral analysis of chemical samples. The core function of Definition AS is to measure the absorption or emission spectra of materials, providing data on their chemical composition and properties.
Automatically generated - may contain errors
Lab products found in correlation
Lightspeed qx i, by GE Healthcare (1 mentions)
Sensation 16, by GE Healthcare (1 mentions)
Lightspeed 16, by GE Healthcare (1 mentions)
Care dose 4d, by Siemens (1 mentions)
Definition as, by Siemens (1 mentions)
Sensation 16, by Siemens (1 mentions)
Definition flash, by Siemens (1 mentions)
Somatom definition flash, by GE Healthcare (1 mentions)
Lightspeed vct, by GE Healthcare (1 mentions)
Sensation 64, by GE Healthcare (1 mentions)
Somatom sensation 16, by GE Healthcare (1 mentions)
Definition flash, by GE Healthcare (1 mentions)
Discovery 690, by GE Healthcare (1 mentions)
Ge discovery st, by GE Healthcare (1 mentions)
Ge revolution 256, by GE Healthcare (1 mentions)
Minitrace cyclotron, by GE Healthcare (1 mentions)
4 protocols using definition as
1
Multi-Modal CT Imaging Protocol for Liver Biopsy
2
Multidetector CT Imaging Protocol for Contrast-Enhanced Studies
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All of the CT images were acquired from one of the following three multidetector CT scanners: a 64-multidetector-row CT scanner (Siemens Definition AS or SOMATOM Definition Flash; a Light Speed VCT (GE Healthcare, Milwaukee, WI, USA) or Siemens Healthcare, Erlangen, Germany) was used. Patients were required not to eat or drink anything for 4–6 h before the examination. The scanning parameters included 120 kv tube voltage, 150–250 mA tube current, 64 × 0.625 mm detector collimation, 350 × 350 mm field of view, 5 mm section thickness, and 1–1.5 mm reconstruction interval. After finishing the unenhanced CT, a peripheral intravenous dose of 120 ml of nonionic iodinated contrast agent (dose 1.8 mL/kg, injection rate 2.5–3.0 mL/s) was given to the patients at the rate of 3–4 ml/s. An axial CT scan of the arterial and venous phases was initiated 25–30 s and 65–80 s after the contrast agent injection, respectively. All of the CT images were collected during an inspiratory breath hold.
3
Standardized Hip Imaging Protocol
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Imaging of the hips was acquired helically in the supine position on five different clinical whole-body multi-detector CT machines (Siemens SOMATOM Sensation 16, Sensation 64, Definition Flash, Definition AS+, and a GE Medical Systems Discovery 690). The acquisition protocol involved imaging inclusively from the superior margin of the acetabuli to the lesser trochanters. All acquisitions were processed with a standard smooth-edge body kernel and reconstructed with axial slice separation ranging from 0.75 to 1.5 mm, equivalent to slice thickness in all cases. In-plane pixel spacing varied from 0.59 to 0.78 mm, with field of view consistently 512 by 512 pixels. Peak kV was routinely 120 kV. When available from the fully anonymised metadata, recorded exposure ranged from 67-274 mAs, varying due to routine use of dose limiting.
4
Multimodal Imaging Protocol for Chest Diagnostics
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All the patients underwent unenhanced chest CT with a multidetector CT scanner (TOSHIBA Aquilion, Tokyo, Japan; SIEMENS Definition AS+, Munich, Germany; GE Revolution 256, GE HealthCare, Chicago, IL, USA; NMS NEuViz 128, Shenyang, China; GE Discovery ST). The CT protocol included the following parameters: tube voltage of 120 kVp, the field of view (FOV) of 320 mm by a matrix of 512×512 and the tube-current with automated modulation. Lung images were reconstructed with a slice thickness of 1.0 mm and were observed at both the lung window (level, −600 HU; width, 1,500 HU) and mediastinal window (level, 40 HU; width, 350 HU).
PET/CT imaging was performed using a GE Discovery ST-8 PET/CT scanner. 18F-FDG was produced and synthesized by the GE Mini Trace cyclotron via an automatic synthesis module, with a radiochemical purity of 95% or greater. Patients were fasted for a minimum of 6 hours before being injected 18F-FDG, at a dose of 3.70–5.55 MBq/kg. The whole body PET scans were acquired in 2-D mode and ranged from the head down to the root of the thigh. The obtained PET data were reconstructed using an ordered subset expectation maximization algorithm (6-bed positions; 3.5 minutes/bed; 128×128 matrix). All images were exported in DICOM format for feature extraction and further analysis.
PET/CT imaging was performed using a GE Discovery ST-8 PET/CT scanner. 18F-FDG was produced and synthesized by the GE Mini Trace cyclotron via an automatic synthesis module, with a radiochemical purity of 95% or greater. Patients were fasted for a minimum of 6 hours before being injected 18F-FDG, at a dose of 3.70–5.55 MBq/kg. The whole body PET scans were acquired in 2-D mode and ranged from the head down to the root of the thigh. The obtained PET data were reconstructed using an ordered subset expectation maximization algorithm (6-bed positions; 3.5 minutes/bed; 128×128 matrix). All images were exported in DICOM format for feature extraction and further analysis.
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