The format for reporting clinically significant carotid stenosis varies substantially across the Veterans Health Administration, the largest integrated healthcare system in the U.S., according to an analysis published online in Radiology.

National guidelines for managing symptomatic patients provide recommendations based on the stenosis ranges from the North American Symptomatic Carotid Endarterectomy Trial (NASCET), but the variability of report formats suggested different algorithms are being used to translate findings into results, according to Eric M. Cheng, MD, MS, of VA Greater Los Angeles Healthcare system, and colleagues.

“The value of a carotid imaging modality is based on how accurately it can help identify patients with stenosis within these NASCET ranges,” wrote the authors, who noted widespread use of non-NASCET ranges, exact percentage stenosis and categories that suggest a wider set of criteria.

For example, ultrasound—the most commonly used carotid imaging modality—has existing guidelines to convert findings into ranges used in NASCET. Cheng and colleagues found, however, that 45 percent of clinically significant results at ultrasonography were reported as exact percentage stenosis instead. “The precision of [ultrasound] has been described as 10 percent at best, so reporting results as an exact percentage stenosis implies a level of precision that is not achievable,” wrote the authors. They add that even when ranges were used on an ultrasound report to describe stenosis, many did not conform to NASCET ranges.

Findings were based on a retrospective chart review that included radiology reports of carotid artery imaging for 2,675 patients hospitalized with ischemic stroke at one of 127 Veterans Affairs medical centers from 2006-2007. A total of 6,618 imaging results were analyzed, including 1,015 considered clinically significant, which was defined as a result with at least 50 percent stenosis. If results were reported as a category, clinical significance was defined as at least “moderate stenosis.” Complete occlusion was excluded.

Among the 695 clinically significant ultrasound results, half were described as a range, and of those, 26 percent did not bracket the key stenosis thresholds of 50 and 70 percent, which are used to determine appropriateness of carotid arterial revascularization. Another 5 percent of ultrasound findings were reported as a category.

On the flip side of the surprising overuse of exact percentages with ultrasound, Cheng and colleagues found an unexpectedly high rate (31 percent) of CT angiography and conventional imaging results were reported in a format other than exact percentage, which reduced the possible precision with those modalities.  

For MR angiographic results, 48 percent of clinically significant results were described as a category, 38 percent as an exact percentage stenosis and 14 percent as a range.

“If a standardized reporting template can be identified, then several key stakeholders can enforce implementation of that standard,” wrote the authors. “Further enforcement would probably occur through pay-for-performance programs, wherein payers such as Medicare are attempting to standardize key processes of care, including the format of radiology reports.” They pointed to initiatives to improve uniformity in mammography reporting as a positive example to follow.