Incidental Extracolonic Findings at CT Colonography

Purpose: To determine the frequency of extracolonic findings at computed tomographic (CT) colonography and the effect of these findings on subsequent patient treatment and cost.

Materials And Methods: Conventional transverse CT colonographic scans in 264 consecutive patients were evaluated independently by two radiologists. Extracolonic findings were classified as having high, moderate, or low clinical importance. The effect of CT findings on patient treatment was assessed with chart review. The cost of additional examinations was calculated by using 1999 Medicare reimbursements.

Results: Thirty (11%) patients had highly important extracolonic findings, which resulted in further examinations in 18 (7%) patients, including ultrasonography in 10, CT in 13, and intravenous pyelography in one. Six patients underwent surgery because of incidentally discovered CT colonographic findings. Two patients with findings of moderate or low importance underwent additional imaging. A total of $7,324 was required for work-up for extracolonic findings (mean of an additional $28 per examination). Three extracolonic malignancies were overlooked at CT colonography.

Conclusion: Additional work-up of extracolonic CT colonographic findings was relatively infrequent but was often worthwhile when performed for lesions classified as highly important. The evaluation of extracolonic structures at CT colonography has definite limitations with regard to solid organs but can help detect serious disease without substantially increasing the cost per patient.