Incidental findings are a growing problem, amid wide variation in follow-up recommendations
In the everyday world, it is commonplace to use the adjectives incidental and ancillary to describe something or someone insignificant; minor even constitutes one definition for incidental. In the world of radiology, though, incidental and ancillary findings identified in imaging studies administered to assess the presence, absence, or treatment response of another condition are far from insignificant.
Rather, they have assumed great importance. Not only is there heightened interest among radiologists in making recommendations for follow-up care after these findings (as the specialty considers and reconsiders its role in the management of population health), but the question of how and when to respond also remains a topic of great debate. The incidental or ancillary finding—sometimes called an incidentaloma—is an increasing phenomenon in radiology.
Leonard Berlin, MD, FACR, serves in the department of radiology at NorthShore University HealthSystem Skokie Hospital in Illinois and is a professor of radiology at Rush University and the University of Illinois at Chicago. He says that such findings surface more frequently than ever before, with CT and MRI exams—especially the former—yielding the majority of them. The catalysts have been a sharp rise in the number of CT exams performed in the United States annually, along with marked improvements in spatial and contrast resolution gained using newer CT equipment.
“In the early 1980s,” Berlin notes, “we were performing just a few million CT scans per year. For the past few years, however, we have been at nearly 80 million CT scans annually. With the equipment that’s available today, we can see tiny areas of density—in the abdomen, bones, and elsewhere—as never before.”
In general, studies of the abdomen and pelvis produce the most troublesome incidental findings. Lincoln L. Berland, MD, FACR, is professor emeritus and vice chair for quality improvement and patient safety, as well as chief of body CT and the 3D laboratory in the department of radiology at the University of Alabama at Birmingham. He states that by default, any imaging exam of a large region of the body is a screening for conditions other than the one that the procedure it is intended to identify or track, and the more extensive the region, the greater the number of possible incidental findings.
As would be expected, Berland adds, incidental findings uncovered during exams of the abdomen and pelvis become more troublesome as patients age. He says, “As an example, in an 80–year-old patient with probable kidney cancer and other already-diagnosed diseases, there are bound to be multiple incidental findings. This is not necessarily so in a young, healthy patient, even with a large-region scan.”
Results of a study 1 published in Archives of Internal Medicine lend credence to these assertions and add fuel to the fire. Specifically, of abdominal/pelvic CT and thoracic CT studies reviewed by the researchers, a respective 61% and 55% yielded an incidental finding. In contrast, nuclear-medicine exams showed an incidental finding in just 4% of studies scrutinized.
CT scans of the abdomen and pelvis uncovered the greatest proportion (9.2%) of incidental findings that were subsequently followed up; of the 1,376 study participants (1,426 exams), nine had ovarian or adnexal masses, and five had indeterminate lung nodules. For every decade of age, people evaluated in the study were determined to be 1.5 times more likely to have an incidental finding.
By some estimates, the likelihood that an incidental finding is (or will become) malignant is quite small. The process of determining which findings warrant follow-up and which should be ignored, however, as well as what that follow-up should entail,