High-Tech Imaging Misadventures
The science of imaging the human body has advanced by leaps and bounds in the last generation. It was only in 1972 that computed tomography (CT) scans began to replace flat plate X-rays with new levels of sophistication. Magnetic resonance images (MRIs) were introduced in 1974. Positron emission tomography (PET scans) followed in 1977. All of these have become household words, familiar to all of us, with references to these diagnostics frequently showing up in church prayer requests.
They have brought much good to medicine, principally in confirming diagnoses intuited by physicians or indicated by simpler tests. They have also become a common way you can become involved in medical misadventures, ranking just behind becoming a permanent patient.
A colleague of mine had a CT scan of his heart to see how a new valve was functioning. It was doing quite well, thank you. The scan reached down to his abdomen, including his kidneys. There was a 4 cm mass near the ureter on one of his kidneys. As soon as I heard about it, I looked up the commentary on this finding. It’s common. Abnormal spots on the lungs, the liver, the kidneys, and the adrenal glands that sit atop the kidney are common incidentalomas, the slang term physicians give to imaging findings that pop up but have nothing to do with the original intent of the exams. My friend’s surgeon said that biopsying it was not an option (I believe that’s mostly true; it’s very difficult), that it had a significant chance of being invasive cancer given its size and shape (I believe that’s not true; see evidence below), and that the kidney had to come out. (This would be true only as an extension of the previous faulty premise.) He cited excellent five-year survival rates for kidney cancer caught before it metastasized and suggested no further treatment would be necessary. When my friend told me this news, I thought, oh boy, this is going to be a classic illustration of two opposing approaches to possible cancer and to incidentalomas.
One school says dying of kidney cancer is much worse than having one kidney. If it might be cancer, it has to come out. The other school says weigh the risks of the surgery, the risks in the future, the likelihood that it is cancer, the more remote likelihood that it is invasive cancer, and wait to see if it grows.
I looked up best estimates—easy to find—that an asymptomatic kidney incidentaloma in an otherwise healthy fifty-year-old man would be a lethal cancer. It was 0.5%.
In the end, the kidney came out. The pathology report said the cells were “abnormal.” Pathology reports are often less than definitive. Both parties went away satisfied—surgeon and patient. I knew better than to bring it up again with my friend. Once the c-word is mentioned, the era of rational thinking is over.
One of our medical authors, Dr. Gil Welch, points out that people, particularly Americans, hate uncertainties. But medicine is all about uncertainties. Often, he says, it’s better to do nothing in today’s supercharged high-tech medical environment. An example from Gil:
We feel trapped by incidental findings. We feel obligated to evaluate them even as we worry that doing so is really not in the patients’ best interests. We also know they lead to more invasive procedures. … In fact, the chance of dying from the liver biopsy needed to evaluate an incidentaloma there (about one to two per thousand) is on the same order of magnitude as the estimated chance that the incidentaloma is invasive cancer.
The following chart shows why so many people are caught in the imaging misadventure drama every year. If an unexpected shadow on a scan happens to you, take a deep breath before you do anything. The chart below may help you be in the proper skeptical frame of mind when you speak to a specialist about the finding.
| Organ | Proportion of people with an incidentaloma on ct scan (a) | Ten-year risk of cancer death (b) | Chance that the incidentaloma is a lethal cancer (highest possible) (c=b/a) | Chance that the incidentaloma is not a lethal cancer (d=1-c) |
|---|---|---|---|---|
| Lung (smokers) | 50% | 1.8 % | 3.6% | 96.4% |
| Kidney | 15% | 0.1% | 0.7 % | 99.3% |
| Lung (never smokers) | 23% | 0.05% | 0.2% | 99.8 % |
| Liver | 15% | 0.08% | 0.5% | 99.5% |
| Thyroid (by ultra- sound) | 67% | 0.005% | < 0.01% | >99.99% |
Some might raise the question of whether an incidentaloma might lead to death in a period longer than ten years. But even if you used a twenty-year time frame (and again with the exception of lung nodules in smokers), it would still be less than 1% of these incidentalomas.
Nor are the risks from exploratory imaging limited to incidentalomas. The scans themselves have risks too: the familiar cumulative radiation risk for X-rays, CT scans, and fluoroscopy; the heightened risks for more invasive intervention to follow; and the invasive procedures that accompany fluoroscopic X-rays.
High tech scans have become a common way you can be involved in medical misadventures.
If you have reduced kidney function, you should be reluctant to accept contrast material in your CT scan. In other cases, always ask which type of contrast material is being used, low or high iodine. Also ask if the enhanced visibility has a vital medical reason or is a radiologist preference. Contrast material in a scan can be a nearly perfect example of unjustified risk.
We have also uncovered an unpublicized risk to MRI patients that radiologists are worried about. This risk could reach class-action suit status in coming years. Millions of people have been subjected to gadolinium-based contrast agents, such as Gadavist, manufactured by Bayer, in MRIs. Gadolinium is a heavy metal that is bound to other agents chemically in a process called chelation, so it can be processed and excreted by the kidneys. As you can imagine, gadolinium-based contrast enhances MRI readings tremendously, since the technology uses magnetic resonance to produce returns and gadolinium is a heavy metal that lights up MRI screens like a Christmas tree.
The only problem is that trace amounts of gadolinium remain in the body long after the scan. Recent findings show that gadolinium can still be detected in the brain months to years after it is injected. Other patients report continued crawling sensations under their skin, and an online gadolinium support group has already been formed. You would need to have a very compelling medical reason beyond radiologist con- venience to want this material injected into your body.
This is far from an exhaustive list of what can go wrong with the generous use of high-tech imaging, but this much is known: it has harmed tens of thousands, killed hundreds—and sometimes made a diagnosis more exact. It has also saved lives by reversing or clarifying a diagnosis. But use it carefully and with your eyes wide open.
The Facts
- The use of hightech imaging has skyrocketed in the past decade: CT scans have doubled; MRI scans have tripled. The less risky modalities are a different story: ultrasound is up 5% per year; conventional X-rays are flat.
- Public health officials estimate at least 30% of high-tech scans are unnecessary, and cumulative radiation from scans now accounts for perhaps 2% of cancers.
The Path of Wisdom
- Ask what additional information can be obtained by moving to a high-tech scan. Will that information affect the recommendations for treatment?
- Consider carefully the pros and cons of acting on an incidental finding from a high-tech scan.
- Investigate the likelihood any incidental finding represents a serious condition, and then make a decision.
- Consider asking for an additional consultation on cells from a biopsy of an incidentaloma.
- Consider not accepting contrast materials in a CT or MRI scan unless you are convinced by the radiologist that the scan will be significantly less reliable without it.