Is intravenous contrast necessary for detection of clinically significant extracolonic findings in patients undergoing CT colonography?

Abstract

To determine whether intravenous contrast (IVC) is necessary for detection of extracolonic findings (ECFs) in patients undergoing CT colonography (CTC). We performed a retrospective review of CT findings in 179 cases of CTC studies performed over 18 months where both pre-contrast (NECT) and post-contrast (CECT) scans were performed in the prone and supine positions, respectively, in the same patients. All ECFs were recorded on a per patient basis and graded according to the colonography reporting and data system classification. There was no significant change in E grade for the cohort (p = 0.171) between the NECT and CECT scans. On the CECT scans, additional findings were detected in 49.1% of patients. Overall, there were 27/179 (15.1%) patients graded E3 and 18/179 (10.1%) patients graded E4 on the CECT study. Compared with the NECT study, there was a decrease of 12.9% of patients graded E3 and no change in the number of patients graded E4. With IVC administration, additional ECFs are detected in nearly half of all patients. However, there was no increase in the number of patients with clinically significant lesions. The risk-benefit ratio of routine IVC administration for CTC in symptomatic patients thus requires further evaluation. This study reviews the utility of IVC in CTC and is thus relevant to current clinical practice at many institutions.