Usefulness of early-phase helical CT for detecting recurrent rectal cancer.

PURPOSE: To evaluate the usefulness of dynamic enhancement of helical CT in the detection of local recurrence of resected rectal cancer. MATERIALS AND METHODS: In 142 patients with a history of curatively resected T2 or T3 rectal cancer, follow-up plain CT indicated that they had a loco-regional recurrent tumor; consequently, they underwent follow-up pelvic helical CT providing accurate early-phase contrast enhancement in the lower pelvic region. The patients were divided into four groups according to the grade of contrast enhancement of the suspected mass-like lesion before and after contrast enhancement, and the correlation between groups and results obtained by biopsy and/or surgery were assessed. If no correlation was found, patients were followed up for a period lasting from 400 days to two years. As of June 2002, results had been obtained for 80 patients, and correlation between these results and grouping by contrast enhancement ratio was analyzed. RESULTS: All patients in the highest-grade group (n=10) had local recurrence. When only the highest-grade group was considered positive, there were no false positives and only one false negative. CONCLUSION: Our results suggest that early-phase contrast enhancement is useful for accurately detecting recurrent rectal cancer. This can be easily achieved using the SmartPrep function, and should be used to distinguish recurrent tumors from postsurgical scar tissue, because these two tissue types do not exhibit similar enhancement patterns.