Imaging Analysis of Gastric Tumors

All data were transferred to GE AW 4.6 workstation (GE Healthcare, Milwaukee, WI, USA), and interpreted by two radiologists with 6 and 10 years of experience in gastrointestinal radiology. Data analysis was carried out independently using GSI Viewer software (GE Healthcare, Milwaukee, WI, USA) with a standard soft-tissue window (WL 40 and WW 400). Regions of interest (ROI) were drawn on the solid part of the tumor (about two-thirds of the area), with the exclusion of peripheral fat, visible vessel, calcification and cystic/necrotic areas. A circular ROI was placed into the aortic arch within the same CT slice, after the exclusion of calcified atherosclerotic plaque. Subsequently, the thickness of tumour was measured and recorded. In order to reduce the individual variation between patients, IC value was normalized by dividing the IC of lesion to that of aorta (nIC=IClesion/ICaorta) [12 (link)]. All IC values were repeatedly measured three times, and the average value was then calculated. Similarly, ROI of the three gastric regions (fundus, body and antrum) was measured for three times, and their average values were calculated.