Virtual colonoscopy

Computed tomographic colonography in preoperative evaluation of colorectal tumors: a prospective study

Background

This study aimed to assess the usefulness of computed tomographic colonography (CTC) in preoperative evaluation of colorectal tumors and the entire bowel including endoscopically inaccessible regions.

Methods

Colonoscopy and CTC were performed for 49 patients. The tumor and the entire colon were assessed, and the results were compared with colonoscopy. The extraluminal findings of CTC were compared with contrast-enhanced computed tomography (CT) of the abdomen and the pelvis in 33 patients. All these patients had undergone surgery. A comparison of results for tumor node metastasis classification between CTC, CT, and histopathology was performed.

Results

Exploration of the entire colon was possible for 89.8% of the patients using CTC and 49.0% of the patients using colonoscopy. Bowel cleansing was assessed as worse with CTC. In the evaluation of tumor location and morphologic type, CTC was congruent with colonoscopy. Colonoscopy enabled approximate tumor size and volume to be evaluated for only 59.2% (29/49) and 30.6% (15/49) of patients, respectively, whereas CTC enabled evaluation of all 48 (100.0%) visualized tumors. Wall thickening, outer contour, and suspected infiltration of surrounding tissues and organs are impossible to determine with colonoscopy but can be determined with CTC. Using CTC, two additional tumors were found proximate to occlusive masses in endoscopically inaccessible regions.

Conclusion

Computed tomographic colonography is a useful method for diagnosing colorectal tumors. It allows the clinician to diagnose tumor, determine local tumor progression, and detect synchronous lesions in the large bowel including endoscopically inaccessible regions.