On Imaging Healthy People

February 23, 2015

Radiologists need to prepare for screening asymptomatic patients.

Consider this:

Lung cancer screening, mammography, and CT colonography are the imaging tests we have collectively, as a profession, paid the most interest and time to in recent years – particularly in regards to advocacy. Whether performing huge trials that influence sweeping policy implementation, responding to accusations about the efficacy of breast cancer screening, or re-emphasizing that our President chose virtual colonoscopy over the “real thing” – we have been publically touting imaging’s role in screening, preserving health, and promoting wellness. Our efforts have been worthwhile. Radiologists now play a greater role in public health than ever before. It’s not unreasonable to expect more imaging-based screening exams in the near future.

Historically, though, we have mostly imaged sick people: people with symptoms, people who needed a diagnosis.

Now we image people for – well – just being people really. And this carries implications for how we offer imaging services, how we interpret images, how we educate patients, and how we teach about risk.

Screening for Disease and Invoking Unease
The concept of using imaging to screen for disease (mostly cancer) seems simple. Look for asymptomatic cancer in appropriate populations, discover it in early stages, treat it, and save lives.  Easy, right? But as any radiologist will tell you, getting an imaging study puts all patients at risk of discovering a dreaded “incidentaloma”. These inconvenient imaging findings carry potential to strike fear in patients, possible need for future follow-up studies, and induce uneasy feelings in physicians. 

Granulomas posing as lung cancer, complex cysts imitating renal cell carcinoma, regenerative nodules acting like hepatocellular carcinoma, and benign adenomas impersonating malignant adrenal adenocarcinoma. Yikes. [[{"type":"media","view_mode":"media_crop","fid":"32253","attributes":{"alt":"puzzle","class":"media-image media-image-right","id":"media_crop_8795651007192","media_crop_h":"0","media_crop_image_style":"-1","media_crop_instance":"3412","media_crop_rotate":"0","media_crop_scale_h":"0","media_crop_scale_w":"0","media_crop_w":"0","media_crop_x":"0","media_crop_y":"0","style":"height: 133px; width: 159px; border-width: 0px; border-style: solid; margin: 1px; float: right;","title":"©RATOCA/Shutterstock.com","typeof":"foaf:Image"}}]]

The patients being screened are virtually always asymptomatic – so there is no clinical picture to shrink the differential. The imaging appearance is the only feature that informs the list of potential ailments, thus, malignancy “cannot be entirely excluded.”

We, as radiologists, are becoming more adept at dealing with these commonly benign incidental findings.  The series of manuscripts addressing incidental findings in the JACR has been ragingly successful and delivered some of the most widely read articles in the history of the blue journal.  Ultimately, however, these guidelines are driven by expert consensus. It is difficult for an individual patient to read about their unexpectedly discovered new mass that is “most likely” benign, react calmly, and follow the consensus guidelines. 

Some experts believe that human beings do not have the brain capacity to realistically assess risk to their own person.  Applying a “20% increased risk of malignancy” to one’s own healthy self is a challenging task for anyone.  Recognizing relative risk and comprehending a small percentage increase of a very small baseline risk may be easy for researchers, statisticians, and wonky-types. But for an individual, it may be impossible. A marginally increased risk of cancer can abolish all rationality and only invoke fear.

To make matters even more complex, our increased propensity to use imaging as a screening tool will unveil more and more malignancies that people are likely to die with rather than die from. Try telling someone not to worry about their low-grade malignancy and to just be patient until they die from something else. It’s a troubling thought. But not far-fetched.

“But Matt,” a skeptic might say, “just wait until other screening tests are developed that don’t involve imaging – such as breathalyzers and blood tests!”

Point taken. Modern screening exams that may be cheaper and involve no ionizing radiation are certainly being developed. But in the modern milieu, when those tests come back positive –asymptomatic patients are likely to get imaging in order to find the cancer. And the cycle begins...

These challenges are by no means insurmountable. However, as a specialty that is predominantly accustomed to imaging sick people, we must understand how this will impact resource utilization and our role in public health. 

Ultimately, if we want to continue increasing radiology’s role in disease screening, we must recognize the dilemmas introduced by imaging healthy people.