Utility of the gastric window in computed tomography for differentiation of early gastric cancer (T1 stage) from muscularis involvement (T2 stage)

Objective To analyze the diagnostic value of using the gastric window in computed tomography for differentiation of early gastric cancer (T1 stage) from muscularis involvement (T2 stage). Materials and methods All patients with pathologically confirmed T1 stage and T2 stage gastric cancer and who underwent endoscopic resection or gastrectomy at our institution from January 2011 to November 2018 were examined. Each patient received an enhanced CT scan of the abdomen before the operation. T staging of tumors based on the CT scans was performed independently by two radiologists using the gastric window (width 150–200 HU, level 80–100 HU) and the abdominal window (width 350–400 HU, level 50 HU). Results Use of the gastric window to diagnose stage T1 EGC led to an accuracy of 88.9% for observer1 and 91.5% for observer2; use of the abdominal window led to an accuracy of 53.6% for observer1 and 51.6% (38/106) for observer2. Use of the gastric window to diagnose stage T2 led to an accuracy of 85.6% for observer1 and 82.4% for observer2; use of the abdominal window led to an accuracy of 52.3% for both observer1 and observer2. For observer1, use of the gastric window had a diagnostic accuracy of 69.2% for stage T1a and 62.5% for stage T1b; for observer2, the diagnostic accuracy was 65.1% for stage T1a and 67.0% for stage T1b. A Kappa test indicated moderate and substantial inter-observer agreement for T staging with gastric window ( κ = 0.598, P < 0.001) and abdominal window ( κ = 0.745, P < 0.001). Conclusion Use of the gastric window in computed tomography provided more accurate staging for T1 and T2 stages of gastric cancer than the conventional abdominal window.