Kidney stone CT scans bring to light other findings

Non-enhanced CT (NECT) scans searching for renal colic turn up clinically important incidental findings in more than one-in-eight cases, according to a study published in the January edition of the Journal of the American College of Radiology.

Kidney stone rates in the U.S. run between 5 and 10 percent of the population, according to study authors Mohammad Samim, MD, MRCS, with the Yale University School of Medicine, and colleagues. For patients who experience kidney stones, there is a lifetime recurrence rate of up to 75 percent.

For suspected kidney stones, NECT is typically recommended and scans performed from the upper pole of the kidneys through the bladder—often capturing findings that are unrelated to the suspected renal colic or other symptoms presented by the patient.

The authors wrote that detecting these incidental findings (IF) often leads to further evaluation and early intervention for other potentially serious conditions, such as early malignancies.

“To standardize recommendations for such ‘incidentalomas,’ the American College of Radiology (ACR) Incidental Findings Committee recently developed recommendations for IF in the abdomen and pelvis based on evidence and expert consensus opinion,” Samim and colleagues wrote.

The purpose of the study, according to the authors, was to determine both the prevalence and type of IFs on NECT scans performed for kidney stones and to characterize them on the basis of the ACR recommendations.

The researchers performed a retrospective review of 5,383 consecutive NECT reports using renal colic protocol performed on adult patients. Incidental findings were defined as anything unrelated to symptoms and were classified “important” if a follow up was recommended.

Samim and colleagues identified important Ifs in 12.7 percent of the scans—and that IF importance increased with age, finding that patients 80 years and older were four times more likely than those between 18 and 30 years old to have an IF of importance.

Additionally, they found women had higher rates of important IF than men—13.4 percent versus 11.9 percent, respectively.

“The uncertainty and additional testing that may occur as a result of some fraction of these findings may pose a substantial clinical and economic burden,” the authors concluded.  “Additional research regarding the utilization of radiographic guidelines to characterize IFs as well as the outcome of their workup is encouraged to further elucidate the significance of IFs and better standardize their management.”