Preoperative T staging of colorectal cancer by CT colonography.

PURPOSE: This study was designed to estimate the accuracy of CT colonography for the assessment of T stage in colorectal cancer.

METHODS: CT colonograms obtained from 246 lesions were reviewed by 3 investigators. Intestinal wall deformity on shaded-surface display and rough appearance around the intestine were studied to assess their relations to T stage. Intestinal wall deformity was classified into arc type, trapezoid type, and apple-core type, defined as a trapezoidal wall deformity involving > or = 50 percent of the circumference of the lumen.

RESULTS: As for intestinal wall deformity, the rate of arc type was higher in Tis/T1 than in T2 (74 percent: 17/23 vs. 24 percent: 8/34, P < 0.0001); the rate of trapezoid type was 17 percent (4/23) in Tis/T1, 59 percent (20/34) in T2, and 15 percent (28/189) in T3/T4 (Tis/T1 vs.T2, P < 0.0001; T2 vs. T3/T4, P < 0.0001); and the rate of apple-core type was lower in T2 than in T3/T4 (18 percent: 6/34 vs. 81 percent: 154/189, P < 0.0001). Arc type, trapezoid type, and apple-core type were primarily associated with T1, T2, and T3/T4, respectively. When these criteria were used, the overall accuracy for T stage was 79 percent. Rough appearance was specific for T3/T4, but insensitive.

CONCLUSIONS: CT colonography can provide important information for the preoperative assessment of T stage in colorectal cancer.