Light speed 16

Patients in our hospital (hospital 1) underwent preoperative chest CT examinations with four types of CT machines from three vendors, including the Toshiba Aquilion16 row, GE Light Speed VCT64 row, Philips Ingenuity 64 row, and Brilliance iCT 128 row CT machines. In the external cohort, patients from hospital 2 were assessed with American Light Speed 16, Light Speed VCT64 row, and Dutch Philips iCT 256-row CT machines. Hospital 3 utilized the SOMATOM Definition Flash and SOMATOM Drive 64-row CT machines from Germany. The patients were instructed to lie in the supine position during the scan, which covered the entire lung field. The parameters were set as follows: tube voltage was set to 120 kVp, with a tube current of 150–250 mAs or automatic tube current regulation. The scanning slice thickness and slice increment were 5 mm, while the reconstruction slice thickness and slice increment were 1 mm in hospital 1 and hospital 2 and 1.3 mm in hospital 3. The lung algorithm or standard algorithm reconstruction was selected, and non-contrast enhanced images were used for analysis.

CT images were acquired from the Picture Archiving and Communication System of our institution and were saved in Digital Image and Communication in Medicine format. Because our institution is an academic medical center with many patients referred from several affiliated hospitals, imaging data were obtained from different scanners (Siemens SOMATOM Definition, SOMATOM Definition AS, SOMATOM Definition Flash, and Sensation 64; GE Medical System Optima CT 660, Discovery CT 750 HD, BrightSpeed S, and LightSpeed 16; Philips Brilliance 64; Toshiba Aquilion, Aquilion ONE, and Aquilion PRIME). The contrast-enhanced CT images were obtained after intravenous iodine contrast injection and reconstructed using a 5 mm slice thickness without gap.