Prenuvo whole body MRI scan

The whole body scan has gained acclaim in the wellness community promoted by celebrities such as Kim Kardashian and popular in places like Silicon Valley. It is a full body MRI that is designed to identify more than 500 conditions from cancer to multiple sclerosis to brain aneurysms. It is preventive screening over the whole body.

The medical rationale is straightforward especially with respect to cancer. Most cancers can be treated if they are detected early. According to Cancer Research UK, for the eight most common cancers, the 10-year survival rate is more than 90 percent when cancer is diagnosed at Stage 1, compared with 5 percent when the disease is found at Stage 4. The full body MRI attempts to detect all types of cancer all at once.

The company Preunvo has garnered the most hype with their whole body scanning operation. For example, the following excerpt is from a Washington Post article on Prenuvo and represents the best case scenario for this type of technique: 

"While MRIs are typically used to diagnose a particular problem, Prenuvo touts the service as a routine preventive measure, like a colonoscopy or a mammogram. Jensen was intrigued, and her husband persuaded her to try the scan on the eve of her 50th birthday.

The day after the scan, which cost $2,499 out of pocket, a Prenuvo nurse called to tell Jensen the MRI had detected a hard-looking two centimeter cyst on her pancreas. Doctors confirmed her fears: She had stage 1 pancreatic cancer.

Jensen, who had surgery to remove the mass — along with a third of her pancreas and her entire spleen — credits Prenuvo with saving her life."

It appears as though the Prenuvo scan saved this person's life by flagging an early stage but potentially deadly tumor (pancreatic cancer) that was surgically removed before it could spread.

MRI has long been a workhorse for cancer screening and monitoring. One example of its growing diagnostic capabilities is a previous post on how MRI improves prostate cancer screening. A specialized MRI technique was developed to diagnose a specific cancer. In particular, multi-parametric MRI (MP-MRI) combined anatomical and functional imaging modalities of MRI to collect information about the prostate tissue.  Compared to the standard of care TRUS-biopsy, the MP-MRI had twice the sensitivity (fewer false positives), but also only half the specificity (more false positives). With Prenuvo, the idea is to extend general MRI screening to the whole body from head to toe.

To this end, Prenuvo has constructed a custom MRI machine for the whole body scan (Figure 1), which received clearance by the FDA in 2018. The entire procedure takes about one hour, and then the scan is read by a licensed radiologist employed by the company. According to the company literature, the results are sent to customers in 5 to 10 business days. 

A big question is the cost. Prenuvo charges $2500 for the full body scan, which is not covered by insurance. At a lower price point ($1800), one can receive a head and torso scan, and for $1000, a torso scan. A torso scan would cover critical organs such as lungs, heart, liver, pancreas, stomach, intestines, rectum, and kidneys. None of these scans are covered by health insurance, and so have to be paid out-of-pocket.

The reaction of the medical community has been subdued or even negative, and there is outright skepticism over the benefits. For example, quite notably In April, the American College of Radiology released a statement saying that there was "no documented evidence that total body screening is cost-efficient or effective in prolonging life." 

There is a particular worry that scans might result in "nonspecific findings" necessitating costly and extensive additional diagnostics. Occasionally, imaging tests reveal benign anomalies referred to as "incidentalomas." This situation can cause patients to undergo a stressful cycle of further tests and possibly complex treatments, each with its own set of dangers.

One can assess the accuracy of a diagnostic test in terms of false positives (patient does not have disease, but test is positive) and false negatives (patient does have the disease, but the test is negative). Given that the whole body scan uses a general MRI scan without contrast, one would expect a higher number of false negatives compared to more targeted diagnostics (e.g. specialized MRI scan or molecular test). Of course, one can also argue that the false negative rate of no scan is 100%, and so the Prenuvo scan is better than that.

There is barely any data measuring accuracy of diagnostic whole body scanning. The New York Times article on Prenuvo mentions the following study:

"A 2019 meta-analysis looked at 12 studies encompassing over 5,000 people who did not have any symptoms of diseases like cancer but had undergone whole-body M.R.I. scans. Among the six studies that had complete data, the researchers found that 16 percent of people who were scanned ended up having false positives. Only one study observed false negatives — meaning the scan missed something — which occurred in about 2 percent of people. Roughly 32 percent of people had an M.R.I that detected an abnormality that could potentially be clinically relevant, but it’s not clear whether those abnormalities would have led to disease or death."

Overall one would not have a lot of confidence in the numbers (e.g. 16% false positive rate) because the total number of subjects in all of the studies put together amounted to only about 5000 or so.  Prenuvo most likely has already scanned many more people than that.

The ramifications of a false positive can be significant. A false positive diagnosis can lead to more diagnostic testing including by CT (i.e. x-rays) or painful biopsy, and worse may result in over-treatment and possible harm from an unnecessary procedure. For example, a relative of mine has cysts on her pancreas that were diagnosed many years ago by MRI. Because of her advanced age, the decision was made not to perform the Whipple Procedure that Ms Jensen underwent as described above, and instead to watch and wait. Many years later and the cysts have not grown.

One can argue that a false positive registered by the Prenuvo scan would be followed up by traditional diagnostic testing that would provide a more accurate result, and so no harm no foul except for the extra diagnostic testing (which as mentioned above could include exposure to ionizing radiation). Alternatively, one could follow up the positive scan with more Prenuvo scanning at a later time to observe whether there is growth (or any other significant change).

The good news is that the MRI scans themselves are basically harmless. Unlike CT scans, dangerous ionizing radiation is not involved. The subject is placed into a powerful magnetic field and subjected to radiofrequency (RF) pulses, both of which are innocuous. In addition, Prenuvo does not employ contrast agents, which are heavy metals injected into the blood that can help radiologists visualize specific tissue diagnostic features. These agents can be toxic to organs like the kidneys which can be an issue for those with kidney problems.

If this all sounds good and you want to get one you will have to be patient. There is a sizeable pent-up demand for the scans, and so the waitlist is long (CNBC): "According to Prenuvo’s website, the next available slot for a full-body scan in New York is in March. The same is true for the Los Angeles clinic. In the Dallas suburb of Irving, there’s availability starting in mid-December."

In summary, the Prenuvo whole body scan is not meant to replace targeted screening such as colonoscopies and mammograms which are more accurate. On the other hand, we don’t screen for pancreatic cancer, and by the time symptoms arise, it is often too late. A powerful argument is that Prenuvo is better than nothing with the primary downside being the cost, and then having a judicious plan to handle false positives which can include follow up Prenuvo scans.

Figure 1. Prenuvo whole body MRI scanner. The whole procedure takes about one hour.