Computer-assisted CT colonography performs well, gets reimbursed

CT colonography aided by computer detection has proven sharp at finding colorectal polyps 6 mm or larger—and at earning reimbursement—in routine clinical practice, where it also had an acceptable false-positive rate, according to a study running in the June edition of the American Journal of Roentgenology.

Timothy Ziemlewicz, MD, and radiology colleagues the University of Wisconsin and UW Health reviewed the cases of 347 consecutive patients whose CT scans received second reads from a computer-aided detection (CAD) system over a five-month period. Their aim was to test the clinical performance of the CAD system while also tracking related reimbursements.

Prospective reads by experienced CT colonography radiologists, together with subsequent colonoscopy when performed, served as the reference standard.

The team found that, in all, 69 patients (mean age, 59.0 ± 7.7 years; 32 men, 37 women) had 129 polyps ≥ 6 mm.

Their key findings on clinical performance included:

• Per-patient CAD sensitivity was 91.3 percent (63 of 69).
• Per-polyp CAD-alone sensitivity was 88.4 percent (114 of 129), including 88.3 percent (83 of 94) for 6- to 9-mm polyps and 88.6 percent (31 of 35) for polyps 10 mm or larger.
• On retrospective review, three additional polyps 6 mm or larger were found during subsequent optical colonoscopy and marked by CAD but dismissed as CAD false-positives at CTC.
• The mean number of false-positive CAD marks was 4.4 ± 3.1 per series.

As for reimbursement for CAD, the researchers found that, over an 18-month period, 31 percent of the total charges for CAD interpretation of 1,225 studies were recovered from a variety of third-party payers.

Among the limitations in their study, the authors acknowledge its single-site design and predominantly screening population, “although this population is precisely the one most likely to benefit from CAD as a second reader to assist in identifying precancerous polyps,” they write. They also note its use of a single CAD system, which may or may not be generalizable to providers using other systems.

Still, Ziemlewicz et al. conclude, CAD performance in routine clinical practice is “similar to previous retrospective evaluations, with excellent sensitivity and an acceptable false-positive rate. Furthermore, we have shown that CAD is being at least partially reimbursed in our clinical practice by third-party payers.”

The combination of good clinical performance and third-party reimbursement, they add, “would suggest that use of CAD in CT colonography will likely increase in the future, especially in light of the recent positive USPSTF screening recommendation for CT colonography.”