Clinicians in quandary as findings with multi-detector-row CT increase
Should you order more expensive tests? Or disregard?
CT has advanced rapidly in recent years, in some cases empowering clinicians to gather huge amounts of data painlessly rather than through invasive procedures. However, there is a tradeoff for the ever-increasing resolution power of the newer scanners: They are picking up a growing number of incidental findings that clinicians must then determine whether to pursue.
It's a quandary because such findings can lead to a cascade of unnecessary tests, runaway costs, and patient anxiety. But they also can uncover clinically significant problems that warrant intervention. Consequently, knowing when to act on an incidental finding is a point of growing concern among imaging professionals as well as payers.
The issue has been the focus of numerous investigations including, most recently, a study lead by Jeremy Burt, MD, who was at Stanford University School of Medicine when conducting this study but is now a resident in the Department of Radiology at Johns Hopkins Hospital in Baltimore, MD.1 Burt points out that that there is little consensus on how incidental findings should be addressed.
"Many feel that incidental findings found on various imaging modalities are 'free' information which, free of cost, should be utilized to further the care of patient. Others are concerned that much of the information given by incidental findings is of questionable value and even potentially harmful," explains Burt.
The chief concerns are further cost, inconvenience, radiation exposure from follow-up imaging, and possible morbidity and even mortality associated with further work-up, he notes. There are also psychological costs associated with receiving a new potentially life-altering diagnosis, Burt adds.
Incidental findings are common
In an attempt to address some of these issues, Burt and colleagues first looked into the prevalence and type of incidental findings that were discovered during cardiac multi-detector-row CT (MDCT) in a group of 459 healthy men and women in their 60s. None of the individuals had been diagnosed with cardiovascular disease, but they were referred for MDCT for the purposes of detecting and quantifying levels of coronary artery calcification.1
A prospective analysis of the images revealed that incidental findings were, in fact, quite common, with 41% of the MDCT scans revealing incidental findings. Of these, 23% or 103 participants had at least one incidental finding that was referred for follow-up. And most of these cases (18%) involved single or multiple pulmonary nodules.1 Burt speculates that the high rate of incidental findings relative to previous studies might have to do with the increasing spatial resolution of MDCT scanners. He emphasizes that these discoveries will only increase as the technology develops.
Certainly, the results of those incidental findings that were referred for follow-up will be telling, and Burt plans to report on this aspect in another study scheduled for publication in the upcoming November issue of the American Journal of Medicine. In the meantime, however, clinicians still must carefully weigh the benefits and risks of ordering follow-up examinations in these cases, as the prevalence of incidental findings will only increase with advancing technology.
Training is a priority
Experts sometimes differ on when it is appropriate to order follow-up tests in a given case, but there is broad agreement that more research into this area is needed to appropriately guide clinicians.
"It is like in the past, with a magnifying glass, you could only see so much, but now with a microscope you can suddenly see a lot more things that you previously just did not have the resolution to detect," stresses Michael Poon, MD, president of the Society of Cardiovascular CT and an associate professor of medicine in cardiology at Mount Sinai School of Medicine in New York City. "So the question is whether seeing more translates into better outcomes, and I think we need to definitely ask that question. As the resolution of the newer scanners is getting better and better, are we doing more unnecessary tests or interventions that make no difference to clinical outcomes?"
Poon points out that there are some general guidelines that can help the clinician make decisions regarding pulmonary nodules, which are very common, but not necessarily clinically significant. "The larger the nodule, the greater the clinical importance of it," says Poon, noting that nodules larger than one centimeter should raise some concern. Additionally, he emphasizes that a single nodule is not as big of a concern as multiple nodules. Poon also says that clinicians should be cognizant of associated findings or coexisting incidental findings, such as fluid in the lungs, that can be indicative of something that is not just a benign pathology.
"Training is crucial," says Poon. "I think all CT training should include what are significant and what are not significant incidental findings, so that we don't [order follow-up] on every nodule or ignore nodules that should be further investigated."
Reference
- Burt J, Inbarren C, Fair J, et al. Incidental findings on cardiac multi-detector row computed tomography among healthy older adults. Archives Internal Med 2008; 168:756-761.
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