Usefulness of hydrogel-CT for detecting and staging of rectosigmoid colon cancer

To demonstrate the usefulness of hydrogel-CT for detecting and staging of rectosigmoid colon cancer.Fifty-four patients with rectosigmoid colon cancers underwent routine CT without (n=27) and with (n=27) rectum distension using a sonographic gel. Rectum distensibility and tumor visualization were evaluated. T and N stages on CT independently recorded by two radiologists were correlated with pathologic staging. Staging accuracies were compared using Fisher's exact test. Diagnostic performances in differentiatingT3 from ≥T3 and N0 from ≥N1 were evaluated using areas under the receiver operating characteristic curves (AZ).Rectum distensibility (3.52) and tumor visualization (3.70) were significantly more scored in the distended group than in the control group (1.44 and 2.04) (P0.0001). Pathologic and CT staging were more correlated in the distended group in both reviewers. Accuracy for staging was higher in the distended group (T: 50-85.2%/N: 59.3-92.6%) than in the control group (T: 45.5-62.5%/N: 33.3-59.3%) without statistical significance except N staging for reviewer 2 (P=0.0091). AZ values for T and N staging in the distended group (T: 0.827-0.989/N: 0.858-0.980) were also higher than in the control group (T: 0.817-0.907/N: 0.544-0.654).Hydrogel-CT can provide better diagnostic performance for T and N staging of rectosigmoid colon cancer.