Two Decades of CT Colonography Prove Safety and Efficacy for Colorectal Cancer Screening, Study Finds

A new 20-year analysis from the University of Wisconsin School of Medicine & Public Health confirms that CT colonography (CTC), a noninvasive imaging method for colorectal cancer (CRC) screening, is a safe and effective tool for early detection and prevention—offering valuable benchmarks for institutions considering implementation.

Published in the American Journal of Roentgenology and led by Drs. Perry J. Pickhardt, Max V. Golden, and David H. Kim, the study reviewed over 15,000 CTC exams performed from 2004 through 2024, providing one of the largest and longest-running datasets of its kind in the United States.

“This extensive experience shows that CT colonography offers a balanced approach—combining the safety of a noninvasive test with the diagnostic strength to detect polyps and cancers before they progress,” said lead author Dr. Pickhardt.

Key Findings: Accuracy, Safety, and Prevention

Among 9,168 asymptomatic screening patients, 15.9% had polyps ≥6 mm, and 4.0% had advanced adenomas—known precursors to CRC. Adenocarcinoma was detected in 0.2% of these cases. Critically, the positive predictive value (PPV) for polyps confirmed at follow-up colonoscopy was 91.6%, demonstrating high diagnostic accuracy.

In terms of safety, there were no cases of colonic perforation or major complications reported throughout the entire study. Additionally, CTC identified previously unsuspected extracolonic malignancies in 0.4% of exams and abdominal aortic aneurysms (AAA) in 0.3%—offering added clinical value beyond colorectal screening.

Utilization Decline and a Path Forward

Despite these strong outcomes, researchers observed a steady decline in CTC use over the study period. Annual CTC volume for primary screening dropped from a peak of over 1,500 in 2005 to just 72 in 2023. Researchers cited a lack of Medicare coverage—only recently approved in 2025—as a primary barrier, along with low awareness among referring providers and concerns over radiation or incidental findings.

“CT colonography has long been underutilized, even though it balances sensitivity and cost-effectiveness better than stool-based or endoscopic options in many cases,” said Dr. Kim, a co-author of the study.

The study’s authors stress the importance of establishing dedicated CTC programs with consistent protocols and quality assurance to ensure high diagnostic accuracy and patient management. The publication includes standardized benchmarks—such as C-RADS categorization rates and extracolonic findings—that practices can adopt when launching new screening efforts.

A Model for Nationwide Implementation

The timing of this study is particularly significant, as CMS’s recent decision to reimburse screening CTC is expected to catalyze broader adoption across the U.S. healthcare system.

“This dataset offers a road map for scaling safe and effective CTC programs nationwide,” said Dr. Pickhardt. “We hope this helps close the screening gap, particularly for patients who prefer a noninvasive option.”

The study was conducted at the University of Wisconsin and supported by internal programmatic resources. Dr. Pickhardt disclosed advisory roles with Nanox-AI, Bracco, GE HealthCare, and ColoWatch, and Dr. Kim is a shareholder in Elucent LLC. All conflict-of-interest disclosures were managed according to institutional policies.