The rise in the number of incidental findings brings ethical and medical dilemmas to the forefront.
The increase in CT scans and other medical imaging in recent years has been accompanied by an increase in the number of incidental findings, both in clinical medicine and in research. In many cases, incidental findings can cause ethical and clinical dilemmas for radiologists.
"There are various definitions for incidental findings, but for the most part, the term refers to an asymptomatic finding that one identifies on a test when he or she is really looking for something else," says Lincoln L. Berland, MD, FACR, lead author of "Managing Incidental Findings on Abdominal CT," an ACR white paper published in the JACR®.1
"An incidental finding is outside of the diagnostic question being asked. So if you're looking at the colon and small bowel in a patient with diarrhea, a finding outside that area would be incidental, but anything you find in the colon would not be incidental," explains Joel G. Fletcher, MD, professor of radiology at the Mayo Clinic in Rochester, Minn., who co-authored a 2010 paper published in the Archives of Internal Medicine on incidental findings.2
Seeing an Increase
It's no surprise that the increase in the number of scans is partly responsible for the boost in incidental findings. In fact, in the United States, the number of CT examinations increased from 26 million in 1998 to 61 million by 2006, according to the JACR white paper. But the rise in CT scans is only one of several factors behind the increase in incidental findings, according to Berland, who is also professor emeritus in the department of radiology at the University of Alabama at Birmingham.
"The technological quality of the images has improved so much that we're finding smaller and subtler lesions," Berland says. "The reporting of incidental findings has also gone up because of heightened awareness about medicolegal considerations," he adds, noting that the issue of what to do with incidental findings has only arisen in the last decade.
The white paper presented five flow charts (available at http://bit.ly/FlowCharts) to help radiologists decide what steps to take following the identification of an incidental finding on a CT scan. Flow charts are available for four different organ systems — liver, kidney, adrenal glands, and pancreas. However, incidental findings are often discovered on MRI scans as well, Berland says.
In response, Berland and his colleagues on the ACR Incidental Findings Committee II are in the process of writing a second paper that they hope to submit for publication by the end of this year. The paper will be based on a review of the literature and will present data on incidental findings in different organs, such as the ovaries, blood vessels, spleen, lymph nodes, and biliary tract, Berland says.
Medical and Ethical Dilemmas
The question of whether to pursue an incidental finding with additional diagnostic tests or even surgery presents a quandary for radiologists. Such findings may create unnecessary medical burden or even harm as well as the potential for curative benefit, according to experts such as Berland and Fletcher. "Much of the problem is the cost, but following up on an incidental finding can also be medically unhealthful," explains Berland. One such case occurred personally with William J. Casarella, MD, FACR, former chairman of the department of radiology at Emory University in Atlanta. Casarella had incidental findings discovered during a CT colonography and had to have subsequent procedures that cost upwards of $50,000, and caused substantial post-operative pain.
Berland, who is also analyzing data on incidental findings from an internal retrospective study of patients at the University of Alabama at Birmingham, states that "some patients have suffered surgical complications or renal failure, and we've even had a death because of treatment of an incidental finding." After a review of prior literature and his own professional experience, Berland estimated that costs of incidental findings range between $28 and $550 per patient.
However, one study suggests that the incidental detection of abdominal aortic aneurysms has contributed to the number of years a patient's life is extended, according to Berland. Fletcher and colleagues state that among 1,376 patients and 1,426 imaging examinations, physicians discovered 1,055 incidental findings, the large majority of which did not affect medical treatment. However, 35 research participants received clinical action based on the detection of an incidental finding. Of those, 32 underwent follow-up imaging. Six of these findings — renal cell carcinoma, small-bowel carcinoid tumor, and others — represented a clear medical benefit; two cases were characterized as clear medical burden; and 24 cases were unclear.
Prevalence May Vary
Some modalities are less likely than others to result in identification of incidental findings that require surgery or follow-up, according to Fletcher's paper. "No incidental findings from MR outside the head, or from ultrasound, plain film, or nuclear medicine, required surgical follow-up," Fletcher says.
However, those performing clinical research in imaging can run into ethical dilemmas resulting from incidental findings. "In research, patients should be told about the potential for an incidental finding before they participate in a clinical trial, if it is the type of research likely to generate an incidental finding, such as a head MR or a CT of the abdomen," Fletcher explains.
"In our Archives study, we had a physician panel look at 35 patients, or about 3 percent of the study cohort of approximately 1,400 who received clinical action based on an incidental finding," he says. Only 1 percent of the patients with an incidental finding were thought to have clear medical benefit, resulting in curative treatment — most for either cancer or infections. On the other hand, 0.5 percent of the patients experienced medical burden from the follow-up; they all had surgeries for benign disease but did not die or encounter post-surgical complications, according to Fletcher.
Importantly, the prevalence of incidental findings may also vary based on imaging methodology, according to Fletcher's study. "Research studies using plain films of the hand in patients with arthritis will generate virtually no incidental findings," he says. "On the other hand, if you're looking at the colon during a CT colonography study, incidental findings will occur in about 40 percent of patients but will be of potential medical significance in approximately 6 to 8 percent."
According to Fletcher and colleagues, CT of the abdomen/pelvis and thorax were the body areas most likely to produce an incidental finding. Of those abdomen/pelvis CT studies, 61 percent produced an incidental finding. Meanwhile, 55 percent of thorax CT scans identified incidental findings. Ultrasonography produced an incidental finding only 9 percent of the time, while nuclear medicine scans produced an incidental finding only 4 percent of the time. Only those incidental findings produced by CT and MR scans of the head yielded incidental findings that received further investigation, Fletcher wrote. Lastly, CT of the abdomen/pelvis produced the most — 9.2 percent — incidental findings that received follow-up, according to the study. Of the 9.2 percent, nine cases were ovarian or adnexal masses, and five were indeterminate lung nodules.
Also the importance to radiologists working in both research and in clinical practice is that incidental findings are more common in older patients, according to Fletcher. "For every decade of age, patients studied in our paper were 1.5 times more likely to have an incidental finding," he says. "Our results translate to a 4-percent increase of an incidental finding for each year of age."
The question remains: Is pursuing incidental findings worth the risk? If it saves lives, then a physician is obligated to say yes. As studies progress, however, perhaps a more definitive answer will be found.
1. Berland L, et al. “Managing Incidental Findings onAbdominal CT: White Paper of the ACR Incidental Findings Committee.” JACR 2010;7:754–73.
2. Orme NM, et al. “Incidental Findings in ImagingResearch: Evaluating Incidence, Benefit, and Burden.” Archives of Internal Medicine 2010;170:1525–32.
By John Otrompke