The waiting room was heavily perfumed, with soaring wood ceilings that reminded me of upscale hotels. As I helped myself to a free seltzer, a shelf full of health books caught my eye. One was dubiously titled “Super Human: The Bulletproof Plan to Age Backward and Maybe Even Live Forever.”

After I donned Prenuvo scrubs, a bearded technician named Zach led me to a large room that housed the MRI machine. It looked like a giant white doughnut.

“Seems like it’s been busy,” I said nervously.

“After Kim Kardashian posted on Instagram, we got, like, a hundred thousand more followers in a week,” Zach said. “It was nuts.”

Zach eased me onto a padded table. He lowered a shield over my chest and covered my head with a helmet. For a moment, panic and claustrophobia swelled within me. I was about to spend an hour like this.

“Try some deep breaths,” Zach said soothingly. Then he placed headphones over my ears and a mirror in front of my eyes, so that I could watch a television behind me. As the table rolled into the scanner, Taylor Swift started playing. I’d finally made it to my concert.

Most of the people I spoke with for this story told me that they were happy they got a preventive MRI. Some expressed a sense of relief in discovering that a nagging pain wasn’t anything serious. A young woman who received an ambiguous finding, which later turned out to be benign, told me, “It was absolutely worth knowing about. The scan gave me a sense of control.” Almost everyone said that they’d recommend the scan to others. “The medical profession is all about fixing what’s broken,” one man said. “This made me feel I could actually get ahead of potential problems.” This is a select group—early adopters with disposable income and access to plenty of doctors. But their conviction suggests that, in a stochastic world, medical information fosters a feeling of agency.

Whether this sense of control is justified is ultimately an empirical question, and one that full-body MRI companies seem only selectively interested in engaging with. Prenuvo was happy to share with me that it had made half a million clinical findings, but it offered few specifics about what these findings were. (Things like mild arthritis presumably count, and the total includes conditions that patients already knew about.) The company claims that around five per cent of people had been alerted to “potentially lifesaving” findings. Prenuvo wouldn’t tell me what proportion of people received incidental findings, or even how many individuals it had scanned. This makes it impossible to do the math when Lacy argues, as he often does, that if everyone in America got a full-body MRI every two years—at a total cost of fifty or sixty billion dollars—the scans would pay for themselves, “because everything is caught early.” Claims like these have a bada-bing, bada-boom quality to them, more reflective of Silicon Valley pitch decks than lived experience.

At the same time, it’s hard not to feel that our current system needs to change. Half a century after the U.S. declared war on cancer, the disease remains the nation’s second leading killer, and many malignancies are diagnosed after they’ve spread. It’s easy to understand why patients would be frustrated with a medical system that only screens for a handful of cancers, and simply waits for most others to emerge. “This debate pops up from time to time, and it’s now playing out along disappointingly familiar lines,” Daniel Sodickson, Ezra’s chief scientist and a radiology professor at N.Y.U. Langone, told me. “Tech enthusiasts: positive. Medical professionals: skeptical. I think the medical community, in response to some earlier failures, has developed a kind of allergy to the idea of proactive imaging.” Sodickson acknowledged that false positives are a problem, but argued that if patients get scanned often enough, artificial intelligence could separate the red flags from the red herrings. “If you see something and it’s largely unchanged from a prior scan, you can effectively rule it out as an item of concern,” he said. “We don’t want to scan more because we’re afraid of false positives—but, actually, scanning more is the best way to deal with false positives!”

Jha, the University of Pennsylvania radiologist, told me that serial scans would be more profitable for Prenuvo than for patients. You sometimes need many scans over many years to spot the difference between benign and life-threatening lesions. He worried about an overdiagnosis epidemic, like the one in South Korea. “It’s extremely hard to say to someone that you personally were overdiagnosed,” Jha told me. “Overdiagnosis emerges when you look at a population. Everyone individually can feel that their cancer was caught and treated appropriately—even though we know, statistically, that this isn’t true.”

When I asked Lacy about the psychological toll of ambiguous findings, he said that ninety-nine per cent of patients that Prenuvo surveyed reported a positive experience. “We will know we’ve succeeded when getting diagnosed with something is not anxiety-inducing,” he argued. “It’s affirming, it’s empowering, because you now have more options available for treatment.”

About a week after my MRI, Prenuvo called to say that the results of my scan would arrive soon. I scheduled a consultation with one of the company’s nurse practitioners. Usually, a report is sent in advance of the appointment; as my consultation approached without any sign of one, I started to worry. Then the nurse called. “Sometimes they don’t release it ahead of time, because it’s better if we go over things together,” she said. This did not reassure me.

There were no visible problems in my lungs, liver, pancreas, or brain, the nurse said. My sinuses were a little swollen, probably from allergies. There was, however, a solitary spot on my prostate. Lesions are graded on a scale from one to five, she explained, based on their likelihood of being cancerous. “Your score is a three, smack dab in the middle,” she said.

The nurse observed that if the lesion proved dangerous, there was always the option of “just scooping it out,” as though it were an errant raisin that had fallen into some ice cream. She encouraged me to talk to my primary-care doctor and a urologist. They’d probably order some tests, she said, and maybe a biopsy. My cascade of care had begun.

After we hung up, I sat at my desk, processing. A three? I thought of an episode of “Seinfeld,” in which George visits a doctor for a growth on his lip. “When I asked him if it was cancer, he didn’t give me a ‘get outta here,’ ” George tells Jerry indignantly. “That’s what I wanted to hear.”

Doctors have a word for accidental findings that produce more questions than answers: incidentaloma. I knew that I probably didn’t have prostate cancer, and that most prostate cancers don’t prove deadly. But I also knew that, because it is so common, it ranks as the second leading cause of death from cancer among men.

A few days later, I sheepishly informed my primary-care doctor that I’d had a full-body MRI. She graciously ordered a blood test; a urologist recommended a dedicated prostate MRI, and, if the results weren’t too alarming, regular follow-ups after that. The immediate cascade would probably cost several thousand dollars, split between me and my insurance. I thought about the other ways in which the money could be spent: months of insulin for diabetic patients; scores of inhalers for asthmatic children; colonoscopies that are proven to find cancer and save lives. When I told Davenport, the radiologist, he shook his head and face-palmed. “Prenuvo probably views your story as a success—I view your story as a tragedy,” he said. “They’ve created in your mind this uncertainty. You were a healthy person, and now you’ve become a patient.”

In the book “Too Much Information,” Cass Sunstein, a Harvard law professor and policy scholar, argues that people want information for two main reasons. Information might have affective value—you feel good when you hear it—or instrumental value, meaning that you can do something with it. Sometimes these values are in conflict: calorie labels at movie theatres can inspire healthy decisions, but they also kind of miss the point of going to the movies. Information also means different things to different people. Continuous glucose monitors are incredibly useful for people with diabetes, but, these days, they’re popular among so-called biohackers, who are often young and healthy and stand to gain much less from them. Too often, the future of medicine isn’t equally distributed. The people who pay for health information may be least likely to need it; they get it to feel good.

If, next year, the lesion in my prostate grows to twice its size, I’ll be happy that I know about it. But odds are that it won’t—and, in the coming years, I’ll need recurring prostate MRIs simply to reassure myself that I am healthy. In this sense, my scan inverted my conception of health. I no longer assume that I’m fine; I want a test to prove it.

Two days after Thanksgiving, Ben from Prenuvo sent me an e-mail. The subject line read “Share the Good News: Your Prenuvo Experience Can Benefit Others!”

Ben sounded as much like a missionary as a marketer. “As you know, our goal is to spread the message of preventative health,” he wrote. “Feel free to connect me to your friends, family or colleagues that could benefit from our scan.” ?