Objective: Contrast-enhanced CT colonography has the potential to detect local recurrence, metachronous disease, and distant metastases in patients with a history of invasive colorectal cancer. The purpose of our study was to determine whether colonic anastomoses prohibit adequate colonic distention on contrast-enhanced CT colonography and to estimate the performance of contrast-enhanced CT colonography in detecting recurrent colorectal carcinoma.
Materials and methods: Fifty patients with a history of resected invasive colorectal carcinoma underwent contrast-enhanced CT colonography and colonoscopy. Colonic distention was graded for different colonic segments. Two radiologists evaluated for the presence of local recurrence, metachronous disease, and metastatic disease. Results were compared with colonoscopy, histology, and clinical follow-up.
Results: Most patients had adequate colonic inflation (37/50, 74%). Eleven of 13 patients with inadequate distention had collapse in the sigmoid colon, usually associated with ileocolic anastomoses. Contrast-enhanced CT colonography detected local recurrences with an accuracy of 94% (95% confidence interval, 83-99%). The accuracy of contrast-enhanced CT colonography for metachronous lesions greater than or equal to 1 cm was 92% (95% confidence interval, 80-98%), but there was only one such lesion, which was missed on initial colonoscopy. Stool, granulation tissue, and inflammation can mimic the CT appearance of local recurrence or metachronous disease and account for false-positive examinations. Contrast-enhanced CT colonography identified five patients with metastatic disease.
Conclusion: Suboptimal sigmoid distention can be seen on contrast-enhanced CT colonography, predominantly in patients with right hemicolectomies. Contrast-enhanced CT colonography is a promising method for detecting local recurrence, metachronous disease, and distant metastases in patients with prior invasive colorectal carcinoma. The technique can also serve as a useful adjunct to colonoscopy by detecting local recurrences or metachronous disease that are endoscopically obscure or by serving as a full structural colonic examination when endoscopy is incomplete.