Publisher Health

For $2,499, Prenuvo will try to predict your future. The company offers a roughly hourlong session of magnetic resonance imaging, or M.R.I., that scans your entire body, searching for early signs of cancer, aneurysms, liver diseases and even multiple sclerosis.

In recent months, images of celebrities and influencers posing in branded scrubs in front of a glossy, cylindrical M.R.I. machine have begun to pop up on social media with notable frequency. Kim Kardashian wore slippers in the post she shared with her 364 million followers last month, writing in the caption that Prenuvo “has really saved some of my friends lives.” In May, the television host Maria Menounos said that a Prenuvo scan had alerted her to a mass that turned out to be Stage 2 pancreatic cancer.

Prenuvo does not pay anyone to promote its products, according to the company’s founder and chief executive, Andrew Lacy, but it does offer free scans to influencers and prominent figures in the wellness industry “in exchange for an honest review if they feel like it,” he said. Some people also receive discount codes they can share on social media, offering their followers hundreds of dollars off the cost of a scan.

The company has sought a glamorous crowd. During New York Fashion Week in early September, it coordinated with the fashion public relations agency Lucien Pagès to set up appointments for “a few” influential people in the fashion world, according to the agency. They included the French fashion editor Olivier Zahm, who wrote on Instagram on Wednesday that he went to get his scan between runway shows. The designer Zac Posen, the model Lily Aldridge and the Vogue editor Gabriella Karefa-Johnson have also posted about the scans.

Many celebrities talk about their health on social media, for example, sharing post-mammogram photos or promoting dubious procedures like colonics and IV drips. But the ones documenting their body scans — complete with nearly identical photo ops — have taken the celebrity health endorsement to new heights in terms of cost.

High-profile proponents have made Prenuvo perhaps the most prominent in a crop of companies offering whole-body scans that are generally not covered by insurance. There’s also Ezra, simonONE and the Stockholm-based Neko Health.

“It’s completely understandable why you’d want to find cancer early,” said Dr. Rebecca Smith-Bindman, director of the Radiology Outcomes Research Laboratory at the University of California, San Francisco. “It would absolutely give you that sense of control over it.”

Most cancers can be treated if they are detected early, she said. But those are largely detectable via other means, like the cancer screening schedule your doctor recommends for you — which is typically covered by insurance.

And considerable harms can come from screening, she and other experts said. 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,” and expressing concern that scans could lead to “nonspecific findings” that require extensive, expensive follow-up.

Dr. Larry Norton, a breast oncologist and the medical director of the Evelyn H. Lauder Breast Center at Memorial Sloan Kettering Cancer Center, said that “there’s just no evidence to support” healthy people undergoing full-body M.R.I. screening, even for people who have a family history of cancer. Dr. Smith-Bindman herself has a family history of cancer, she said, and she would not consider getting a full-body scan like Prenuvo’s.

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.

“If you scan more, we see more,” said Dr. Thomas C. Kwee, a radiologist at the University Medical Center Groningen in the Netherlands and an author on the meta-analysis.

“You wonder, is this really good that you’re doing for the patient?” Dr. Kwee said.

Prenuvo’s visibility on social media is unusual, said Joshua Cohen, a health economist. Other diagnostic scans, such as X-rays for broken bones and PET scans for Alzheimer’s disease, are prescribed by doctors after evaluation, not spread by word of mouth on Instagram.

That visibility has driven some people to book the scans despite feeling perfectly healthy. One of them is Jennifer Jones, a 44-year-old woman in St. Louis, who first heard about Prenuvo on social media. She said she wanted to get a scan in part because her sister has lung cancer.

Ms. Jones said she was aware that many doctors are skeptical of the scans for healthy people, but she had “no doubts that it’s legit.” To her, the price is well worth it compared with the potential costs, financial and otherwise, of future illness. “I would literally do anything to have preventive options,” she said.

The Risk of False Positives

Our bodies commonly contain abnormalities, like lumps and masses and scars on organs, that can be detected by M.R.I. Dr. Smith-Bindman compared these to moles on our skin.

An M.R.I. alone can’t always tell you whether a finding is benign or troubling, said Dr. Dushyant Sahani, chair of radiology at the University of Washington, and patients often have to undergo additional testing.

A representative from Prenuvo said that 5 percent of people who get a Prenuvo scan are alerted to “potentially life-saving findings.”

Mr. Lacy, the Prenuvo founder, said the theoretical risks around false positives don’t reflect Prenuvo’s technology, which he says is more precise than the CT scans at the center of much of the screening research.

But according to Dr. Smith-Bindman, “the problem has nothing to do with the technology.”

“The problem has to do with the profound, normal variation in our bodies,” she said, and the likelihood of nodules and abnormalities that a very sensitive machine will find.

Preventive screenings will likely find early cancers, but not every instance of cancer develops into devastating disease, Dr. Smith-Bindman said. And once any abnormality is detected, doctors will pursue it. This can result in “major surgery and radiation and chemotherapy,” she said, for an early cancer that might never have developed into a true health risk.

For a small number of patients, detecting and treating an early cancer will have a profound benefit, but “the number of benign tumors so outnumbers the number of aggressive tumors,” she said.

Additional tests can bring new complications and potentially unnecessary exposure to radiation through tests like pet CT scans. “You don’t want to just willy-nilly bomb everybody with X-rays,” said Dr. Michael Pignone, chair of internal medicine at Dell Medical School at the University of Texas at Austin and a former member of the U.S. Preventive Services Task Force. Intervention can also be invasive and expensive, he said.

“How many cancers will we cause from the radiation that comes from the PET/CT after doing the full body M.R.I.?” Dr. Smith-Bindman said.

Dr. Pignone said he worried about what he called the “opportunity cost” — the effort people invest in follow-up imaging for M.R.I. findings, instead of in following the recommended schedule for health screenings or focusing on other facets of preventive medicine. A wealth of research has gone into determining which screening tests are most effective, he said, and those are recommended for the general population.