Local invasion of gastric cancer: CT findings and pathologic correlationusing 5-mm incremental scanning, hypotonia and water filling

OBJECTIVE: Our purpose was to assess the accuracy of CT with drug-induced hypotonia and water filling in revealing the depth of tumor invasion of the gastric wall, according to the T factor of TNM classification, and to verify the capability of this technique in differentiating diffuse from intestinal gastric cancer. SUBJECTS AND METHODS: Forty patients (age range, 35-78 years) with histologically proven gastric tumors underwent CT, in the prone position, with drug-induced hypotonia and water filling. The images were prospectively reviewed by two radiologists who were asked to assess the depth of tumor invasion in the gastric wall. The thickening of the hypodense layer and the contrast enhancement of lesion were measured. RESULTS: CT correctly assessed gastric wall invasion in 77% and 82% of cases for observers A and B, respectively; overstaging was 20% and 15%, respectively; and understaging occurred in 3% of cases for both observers. Diagnostic sensitivity for serosal invasion was 100% for both observers; specificity was 80% and 87%, respectively. Substantial agreement between the observers was obtained (kappa = .6). Diffuse and intestinal cancers could be differentiated by CT in 92% of cases, considering the thickening of the hypoattenuating layer of the gastric wall (diffuse cancer: 7 +/- 1.2 mm; intestinal cancer: 1.4 +/- 0.4 mm) and contrast enhancement (diffuse cancer: 85 +/- 8.2 H; intestinal cancer: 51 +/- 3 H). CONCLUSION: CT with patients in a drug-induced hypotonia and in a prone position, and using water filling, is a promising technique for evaluating the depth of tumor invasion and for differentiating intestinal from diffuse gastric cancer