Publisher Health

It wasn’t that I thought medical imaging was simple, precisely. I understood that a real human body is complicated — that the anatomy textbooks were the map, not the territory. I understood that the plastic dummy with its removable organs was a model, not an exact representation; that the brightly colored images hanging in the doctor’s office were not photographs; that the episode of “The Magic School Bus” in which the class travels through Arnold’s digestive system was not a documentary. Still, what I did not anticipate was that when confronted with an image of my own body — the product of the rotating series of X-rays known as a CT scan — I wouldn’t recognize it at all. I don’t mean as myself, but as anything.

For most of human history, there was only one way to see inside the body: You cut it open. When, in 1628, William Harvey published “De Motu Cordis,” his theory of the circulation of blood, he relied on vivisections of dogs and sheep. To produce the detailed anatomical drawings in “Gray’s Anatomy,” Henry Vandyke Carter relied on human cadavers. It wasn’t until 1895 that a physicist named Wilhelm Röntgen tried something new: He put the hand of his wife, Anna, between a cathode-ray tube and a photographic plate. There it was — her skeletal hand. Anna was revolted. “I am seeing my own death!” she is said to have screamed. In Thomas Mann’s novel “The Magic Mountain,” set a decade or so later, the tubercular Hans Castorp too saw “his own grave” in the X-ray — “the flesh in which he moved decomposed, expunged, dissolved into airy nothingness.”

I am the beneficiary of more than a century of acclimation to the idea of seeing inside yourself. The X-ray, along with all the imaging technologies that followed, is one of modern medicine’s routine little miracles, just like insulin, penicillin, vaccines and effective pain treatment. We see inside bodies all the time now. On TV, doctors examine X-rays and ultrasounds for clues. On social media, a grainy fetal shape floating in the void tells us that a friend is pregnant. A trip to the dentist yields the alien sight of your jaw flattened out and hung up for display.

Radiology can be subjective — not as subjective as, say, art criticism, but not cut and dried.

From my CT scan, I expected a brush with mortality — the opportunity to see the forbidden land of my own guts, to contemplate their eventual decomposition. By that point I had already had an organ removed (my gallbladder), and I suppose I expected to register its absence somehow. What I saw instead was just shades of gray and blobs of darkness. Nothing was recognizable as an organ. At one point, I remember, the doctor directed me to pay attention to something that, in his own words, did not look like anything at all. That, he wanted me to know, was my pancreas. He was right: It did not look like anything at all. If, for Anna Röntgen and Hans Castorp, the X-ray produced something that was undeniably and terrifyingly their own body, I was having the opposite experience. Whose body was this? Was it a body at all? Without the doctor there to tell me what it was I saw, I would never have known.

In popular culture, medical imaging represents a simple statement of fact, a question resolving into certainty. Watch episodes of the medical drama “House, M.D.,” and you will see imaging confidently used to diagnose psychopathy, to tell whether somebody is lying, even to visualize the subconscious. People lie and bodies deceive, but tests and scans do not. And so, in the real world, one submits to these devices nervously, as one would to some kind of truth serum or all-seeing eye: There is no hiding here.

Even when we imagine a superhero with X-ray vision, we imagine somebody who sees through the inessential to the essential. In a scene in the 1978 “Superman,” the Man of Steel flirts with Lois Lane first by scolding her for smoking, then by scanning her for lung cancer. (Her lungs glow pinkly and cutely for a moment before he informs her that she’s all clear. Later, at her request, he tells her the color of her underwear.) Like his superstrength, Superman’s X-ray vision is allied to his virtuous nature: His eyes tell the truth and can’t be fooled.

Nobody expects strict medical accuracy from superhero movies. But popular science narratives are hardly more cautious. We are often breathlessly informed, for instance, that parts of the brain “light up” when presented with certain stimuli, telling us precisely what people are thinking and feeling and why. (Of course, parts of the brain do not light up at all — only their images on an f.M.R.I., indicating blood flow.) Even in everyday life, medical images convey an official certainty that’s hard to obtain through other means. I’ve known friends to forgo different parts of the medical process throughout pregnancies, but the pregnancy-announcing sonogram is de rigueur. Without that image to show friends, you simply aren’t pregnant, socially speaking; you just might be.

For medical professionals, though, all these imaging techniques are imperfect tools, just another way to get a partial idea of what might be happening inside a human body. You have to be trained to read them at all. The doctors on “House” run and pore over scans themselves, but in reality both creating and interpreting CT scans are specialized jobs. Radiology can be subjective — not as subjective as, say, art criticism, but not cut and dried. In the future, artificial intelligence may take a greater role in interpreting results — but it will not make the experience any less alienating if, instead of depending on human expertise to analyze your body, a computer program is making judgments and flagging risks based on patterns and correlations even the doctors may not be able to see.

All we want from a picture is reality; all we ever get is representation. From medicine, we want pure science, but what we get is a complicated tangle of guesswork and certainty, tried-and-true and trial-and-error. You can undergo countless tests without reaching clarity. Even when doctors have identified the main problem — when their ability to operate and repair feels truly godlike — there remain the things they simply don’t know.

It doesn’t look human, the picture on the screen. I have watched professionals use ultrasound to search my arms for veins, looking for spots of black in a field of dark gray and then plunging a needle in a promising spot. Yet it never quite felt as though it was my arm over there on the screen. It’s as if I had another, more real body that could be glimpsed only temporarily, through arcane practices into which I had no insight. What I wanted from a CT scan was a particular kind of self-knowledge, even if it was just an understanding of how my organs looked packed together; what a relief it would have been to confront something as certain and solid as my own grave on the computer screen. Instead I saw the only thing I’ll ever see in any picture: a mass of shapes that might mean something and might mean nothing at all.

Some time after I underwent surgery, the surgeon showed me photographs of the procedure itself. Like the CT scan, the photographs were chaotic and confusing, but they were at least fleshy. I saved some, thinking I might be interested in them later. Months later, scrolling through my pictures, I ran across some thumbnails of uninteresting heaps of meat. What’s that, I wondered, and why had I saved these boring and frankly slightly disgusting images? Then I remembered — it was me, it was me, it was me.

Opening illustration: Source photographs from Getty