Optima ct540

All CT examination was performed using two multidetector CT scanners (Somatom Perspective, Siemens, Germany, and Optima CT 540, GE, America), using the following parameters: tube voltage = 120 kVp, tube current (regulated by automatic dose modulation), 30–75 mAs, pitch = 1–1.25 mm, matrix = 512 × 512, slice thickness = 5 mm, and FOV = 350 mm × 350 mm.
Image reconstruction was done at a slice thickness of 1–1.25 mm. All were the initial CT scans at the time of patients’ admission and are performed as non-contrast studies. Two experienced radiologists (20 years of experience) independently reviewed all the scans, and they were blinded to the patients’ clinical and laboratory data.

Chest CT scans were performed with a single inspiratory phase in one commercial multi-detector CT scanner (Optima CT540, GE Healthcare, U.S.A.). Patients were instructed on breath-holding to minimize the motion artifacts. CT images were acquired by the protocol of tube voltage, 100–120 kVp; effective tube current, 110–250 mAs, detector collimation, 0.625 mm; slice thickness, 1 mm; slice interval, 0.8 mm. Based on the raw data, the CT images were reconstructed by iterative reconstruction technique if possible.
The image analysis and grading were performed by three experienced radiologists, including Wei Chen, Zhihan Yan and Chongyong Xu, who have 10 to 15 years of experience in thoracic radiology, respectively. The final scores and grading were determined by consensus. The distribution of lung abnormalities was recorded as mild (axial CT shows peripheral and subpleural ground glass attenuation, Fig. 1a), moderate (the high-density shadow of plaques involving multiple lung lobes (≥ 3), CT shows ground glass, cloud flocculent or paving stone like changes, at least 2 lung lobes show pulmonary consolidation, local pulmonary fibrosis, and air bronchograms sign can be seen, Fig. 1b), or severe (CT showed diffuse consolidation [minimum of 80% of pulmonary or involving of 4 lobes] or cord like changes, and fibrosis was formed, Fig. 1c).Fig. 1

CT grading of COVID-19

All CT examination was performed using two multidetector CT scanner (Somatom Perspective, Siemens, Germany and Optima CT 540, GE, USA), using the following parameters: tube voltage = 120 kVp, tube current (regulated by automatic dose modulation) 30–75 mAs, pitch=1–1.25mm, matrix = 512 × 512, slice thickness = 5 mm, and FOV = 350 mm × 350 mm.
The patients were in the supine and headfirst position and received scanning with breath held. No contrast was administered. All images were transmitted to the post-processing workstation and reconstructed using high-resolution and conventional algorithms at a slice thickness of 1–1.25 mm.
Three experienced radiologists (20 and15 years of clinical experience in chest imaging) reviewed all the scans; they were blinded to the patients’ clinical and laboratory data. The final decisions were established by consensus.