A new fad has emerged: the full-body MRI scan.
The interest in this high-tech health diagnostic comes from the notion that the scan can catch health issues, including cancer, early. With a price tag of $2,000 to $2,500, they aren’t an option for many people, and they are not covered by health insurance.
But are they even worth it in the first place?
For almost everyone, the answer is no, says Michael Rosenthal, MD, PhD, a Dana-Farber radiologist and computer scientist. Rosenthal puts these scans into perspective below and answers several questions about how they work.
Are full-body MRI scans an effective way to screen for cancer?
There is no evidence that full-body MRI scans are beneficial for people of average risk. If there were clinical evidence that they were effective, such as a clinical trial showing that many people benefitted from these scans, then they would be incorporated into standardized screening protocols. The United States Preventive Services Task Force (USPSTF) recommendations and the National Comprehensive Cancer Network (NCCN) provide excellent, meticulous analyses of screening technologies, and neither entity currently recommends full-body MRI for average-risk screening.
Are full-body MRI scans used at cancer centers today?
Yes. There are very few applications for whole-body MRI, but the ones we have are very important. For example, we use them for routine screening of people with Li-Fraumeni syndrome, a hereditary disorder that puts people at an extraordinarily high risk of cancer anywhere in the body, relatively early in life.
The first full-body MRI I ever read was of a young person with Li-Fraumeni Syndrome. I found three cancers that were still treatable. For this population, the benefit of the scan is very high.
Why wouldn’t a person with an average risk of cancer benefit the same way?
In a young person with an average risk of cancer and no symptoms, it is very unlikely that a full-body MRI scan would find cancer. The scan might find abnormalities that need to be further imaged or biopsied under current guidelines. That person might end up getting a CT scan, ultrasounds, or biopsies, all of which add expense, anxiety, and risk to the patient. The person might be hurt by some of those efforts without a significant likelihood of being helped.
As you age, your risk of cancer does increase. But aging people develop other conditions, as well. A full-body MRI scan of a 65-year-old might pick up several signals, all of which would need to be worked up. Even in the older average-risk population, most of the things that we see on MRI end up being benign, but the work-up of those findings can be stressful and, rarely, harmful.
There is a lot of benefit to an individual if you find cancer early, but that comes with a broader risk of a harm that has to be balanced.
What kind of harm could come from having something checked out?
Take pancreatic cancer as an example. If a full-body MRI finds a suspicious signal on the pancreas, the next step is to do an endoscopic ultrasound. A doctor will put a little camera down your esophagus and into your stomach to look at the pancreas. If they see something suspicious, they’ll take a little piece, a biopsy, for investigation.
These procedures introduce a risk of complications, even when performed by experts with low complication rates. In the average risk population, the risk of pancreatic cancer is low enough that many of those biopsies would be false alarms. It’s a lot of potential harm, possibly even the risk of death, that isn’t necessary for most of those people.
Could a full body scan that doesn’t find cancer give a false sense of security?
Possibly. It is essential for people to continue with recommended cancer screening such as mammography, colonoscopy, or any other recommended targeted screening because these have been found to be effective in carefully designed studies. A full-body MRI is not in any way a substitute for any of those things.
People should also follow up with a doctor on anything unusual, such as unexplained weight loss, unexpected or inexplicable pain, or other symptoms. People know their bodies really well. Better than an MRI knows their bodies. If something doesn’t seem right, see your doctor, go through the specific workup. In some cases, that workup might include a targeted MRI.
How does a full body scan work?
Full body scans can be done using magnetic resonance imaging (MRI), computed tomography (CT) or positron emission tomography (PET). All of these imaging techniques raise the same concerns and are not recommended for cancer detection in asymptomatic adults.
An MRI scan works by using a magnetic field and radio waves to create detailed 3D images of organs and tissues in the body. MRI scans stand out from the others because, unlike X-rays, CT scans, and PET scans, it does not involve radiation that can hurt your body.
But it does involve physics. We use specific protocols, a little like recipes, to apply different physics using the scanner so we can get different images back. Imaging the whole body with these different recipes to get a full picture would take a very long time.
What is the difference between a full-body MRI and a targeted MRI?
A full-body MRI scan is like a 40,000-foot flyover. You can see a lot from that vantage point, but you can’t see everything. For a patient with Li-Fraumeni syndrome, who is at risk of cancer virtually anywhere in the body, that wide range view is of value.
Targeted MRI focuses on a specific organ or area of the body. It might take the same amount of time as a full-body MRI, but it will collect much more information about that area. For example, at Dana-Farber, our diagnostic pancreas imaging uses about 16 different protocols that look for fluid, different kinds of soft tissue with and without fat, and with contrast dyes that we can see move through the tissues so we can see blood supply.
The protocols are different for every organ, but they are very nuanced and detailed and produce high-quality images. A targeted scan might make sense for someone with symptoms or for someone who has an inherited high risk of a specific cancer.
What role does artificial intelligence have to play when it comes to MRI imaging?
Artificial intelligence (AI) is already used in diagnostic imaging such as mammography. For an AI-based tool to be of medical value, it needs to be trained with high-quality images for a specific purpose. The AI also needs to preserve the original image, which is the primary clinical data. And for that AI to be used by doctors to guide a medical decision, it needs to be tested and proven to be beneficial to patients in a clinical trial.
We are starting to see AI in use that might not meet these standards, so it’s important to be aware. For example, it is possible to train an AI model with MRI images of healthy people and teach it to create images that look like high quality MRIs.
But these types of images can be as misleading as Instagram filters. They can take a low-quality scan that has captured about 10% of the data needed to create a high-quality image and then use the AI to fill in the blanks without really knowing what was in those blanks for that patient. This use of AI can be really misleading for patients and for radiologists if they aren’t aware of how the image was created.
For people who are concerned about cancer and want to do everything possible, what do you recommend they focus on?
Routine prevention is the most important thing. Talk to your primary care doctor and stay up to date on recommended cancer screening such as colonoscopy and mammography.
Stay in touch with your body and let your doctor know if you have symptoms or if you sense anything that is out of the ordinary.
And if you see a pattern of cancer in your family, consider speaking with a genetic counselor.