• Perry J Pickhardt, Loredana Correale, Lia Morra, Daniele Regge, and Cesare Hassan.
• 1 Department of Radiology, University of Wisconsin School of Medicine and Public Health, E3/311 Clinical Science Center, 600 Highland Ave, Madison, WI 53792-3252.
• AJR Am J Roentgenol. 2018 Jul 1; 211 (1): 25-39.

ObjectiveThe purpose of this study was to perform a systematic review and meta-analysis of published studies on CT colonography (CTC) in which extracolonic findings were assessed.Materials And MethodsA systematic review of studies of screening CTC and of CTC to evaluate symptoms (1994-June 2017) was conducted to estimate the rate of extra-colonic findings and associated additional workup recommendations. The primary outcome was potentially important extracolonic findings, defined as CT Colonography Imaging Reporting and Data System (C-RADS) category E4 or as having high clinical importance (if C-RADS was not used). Secondary outcomes included likely unimportant extracolonic findings (i.e., C-RADS category E3 or similar). Random-effects and meta-regression analyses were used to generate pooled estimates and to explore risk factors for extracolonic findings related to various cohort characteristics.ResultsPrimary data were acquired from 44 studies (49,676 patients). The pooled rate of potentially important extracolonic findings was 4.9% (95% CI, 3.7-6.4%) with a high degree of heterogeneity (I2 = 95%). This estimate progressively declined over time (9% per year since 2006) and was significantly related to the reporting system (lower for C-RADS than for low, moderate, high clinical significance reporting). C-RADS-specific meta-analysis (32,746 patients) showed rates of potentially significant extracolonic findings in 2.8% (95% CI, 1.9-3.5%) of the cohort without symptoms and 5.2% (95% CI, 3.5-7.6%) of the cohort with symptoms and in 5.7% (95% CI, 3.3-9.8%) of seniors (≥ 65 years) versus 2.3% (95% CI, 1.2-4.5%) of those younger than 65 years. The overall pooled rates of recommended workup were 8.2% (95% CI, 6.6-10.1%) for all extracolonic findings and 4.0% (95% CI, 2.7-5.9%) for potentially important extracolonic findings.ConclusionWith use of the more robust C-RADS classification, potentially important extracolonic findings at CTC occur in less than 3% of cohorts without symptoms. For all extracolonic findings, the rate of suggested or recommended additional workup is approximately 8% but decreases to 4% for potentially important extracolonic findings.

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