Efforts to expand CT colonography (CTC) screening in the U.S. could use deliberate measures to establish dedicated centers and prevent uneven performance or inconsistent patient management during initial rollouts, say researchers reporting 20-year programmatic results.
The team led by Perry Pickhardt, MD, from the University of Wisconsin School of Medicine and Public Health in Madison, analyzed data from nearly 12,000 patients and over 15,000 colorectal cancer screening (CRC) examinations performed there between April 2004 and March 2024. The group’s summary, correlation with subsequent optical colonoscopy findings, and benchmarks were published July 23 in the American Journal of Roentgenology (AJR).
First, the findings support CTC screening as a safe, noninvasive test for CRC prevention and detection with additional extracolonic assessment, according to the group.
- Of 15,431 screening exams (6,258 women, 5,302 men; mean age, 56 years), 9,168 were performed for primary asymptomatic screening.
- A polyp ≥ 6 mm was detected in 15.9% of examinations, and polyp detection had a positive predictive value of 91.6%.
- Also, 0.2% of examinations detected histologically confirmed adenocarcinoma, yet 4% detected histologically confirmed advanced adenoma — a CRC precursor, according to the authors.
- Additionally, CTC detected in this group unsuspected extracolonic malignancies in 0.4% of examinations and abdominal aortic aneurysm in 0.3% of examinations.
- No major complications occurred after any examination, the authors noted.
Furthermore, distributions of C-RADS colorectal and extracolonic categories, positive predictive values, and most frequent histologic results may provide benchmarks for practices seeking to establish a center of excellence for CTC screening, added Pickhardt and colleagues Max Golden, MD, and David Kim, MD.
Notably, the screening-focused CTC program adopted a range of measures for standardization and quality assurance. The group described dedicated coordinators handling the intake (including the handling of insurance issues), preparation, initial post-test disposition, and follow-up of patients undergoing CTC examinations.
Additionally, training and performance measures include participating technologists who perform CTC examinations and radiologists, and case results are documented in a comprehensive clinical CTC database.
The radiologists conducted their interpretations using dedicated software (V3D Colon, Viatronix) with a 3D-2D hybrid approach for polyp detection, according to the report.
“These 20-year programmatic results can provide benchmarks for practices seeking to start CTC screening programs,” Pickhardt and colleagues said.
While the team highlighted the potential for boosted CTC utilization rates following a national Medicare reimbursement decision in January 2025, they also acknowledged low utilization and an overall lack of CTC screening uptake.
Annual volume of CTC examinations performed for primary evaluation substantially decreased from a maximum of 1,589 in 2005 to 72 in 2023, with a minimum of 70 in 2020, the group reported.
Likewise, annual volume of examinations performed for asymptomatic screening decreased from a maximum of 1,532 in 2005 to a minimum of 53 in 2023.
Annual volume of initial examinations performed for symptomatic evaluation also decreased, from a maximum of 57 in 2005 to a minimum of 19 in 2023, while the number of exams performed after incomplete optical colonoscopy varied from a minimum of 65 in 2005 to 80 in 2023, with a maximum of 111 in 2008.
“While the study institution has performed relatively large volumes of CTC examinations, CTC has overall played a very small role in CRC screening in the adult U.S. population to date,” Pickhardt and colleagues said.
They cited that stool DNA testing (Cologuard) had a likely prominent impact on CTC volumes in the later portion of the study period, as did a lack of buy-in and awareness from gastroenterologists and other primary care providers, according to the group.
However, “through proper technique, CTC screening can provide noninvasive CRC prevention that is lacking with stool-based tests, avoid the complications associated with primary [optical colonoscopy] screening, and provide the unique additional benefit of extracolonic evaluation,” Pickhardt et al concluded. “Efforts are warranted to address decreasing utilization.”
Read the complete study here.