Results from the CT Colonography Reporting and Data Systems (C-RADS) could establish baseline values for CT colonography (CTC) screening, according to a study published in the June American Journal of Roentgenology.

Established in 2005, C-RADS was created to classify CTC findings and apply the advantages of structured reporting to colorectal cancer screening. “Standardized reporting systems for screening examinations promote quality and consistency in diagnostic performance and offer a means for providing quality improvement and enhanced patient care for clinical screening programs,” wrote the study’s lead author, B. Dustin Pooler, MD, of the University of Wisconsin School of Medicine and Public Health in Madison, and colleagues.

Although C-RADS has become the standard for reporting colorectal and extracolonic findings at CT as well as classification of patients to guide management after screening, no large-scale studies have acted as a reference for the distribution of C-RADS categorization within a clinical screening program thus far. Pooler and colleagues sought to offer initial benchmark values for C-RADS classification scores that could be used by other programs for comparison and creation of quality assurance measures.

The researchers prospectively classified CTC results according to C-RADS from a seven year period. The study included colorectal and extracolonic findings from 6,769 asymptomatic adults between the ages of 50 and 79. The C-RADS classification rates and outcomes for positive patients were also analyzed.

Results were classified as “C” for colorectal and “E” for extracolonic. The classification rate for C0, or inadequate study, was 0.7 percent. Rates for C1 (normal colon or benign lesion), C2 (intermediate polyp or indeterminate finding), C3 (polyp that is possibly advanced adenoma), and C4 (colorectal mass that is likely malignant) were 85 percent, 8.6 percent, 5.2 percent and 0.6 percent, respectively.

Of the study’s subjects, 14.3 percent were positive for C2 through C4. The researchers found that positive findings were more frequent among men at 17.5 percent than women at 11.6 percent. Positivity increased with age, as 13.4 percent of patients between 50 and 64 years old were positive and 21.8 percent of patients between 65 and 79 were positive.

In terms of the extracolonic evaluation, 86.6 percent of patients either had negative or unimportant findings. Extracolonic findings that were likely unimportant but indeterminate were discovered in 11.3 percent of patients, while 2.1 percent had likely important extracolonic findings. Overall, E3 (likely unimportant but incomplete characterized) and E4 (potentially important finding) scores increased for older and female patient cohorts.

The researchers identified areas of improvement for C-RADS, including modification for separation of submucosal, extrinsic or nonneoplastic lesions for colorectal findings and separation of finding significance and management recommendation in the lexicon for extracolonic findings would also be helpful.

“Our single-center results categorized by C-RADS may serve as initial benchmark values for comparison by other clinical screening programs and for the generation of quality improvement measures,” wrote Pooler and colleagues.