Almost all of us have looked at medical imaging results and wondered how seriously to take them. Today I have an amusing cautionary tale, a case study that leaves no doubt about just how misleading pictures of the inside of your body can be.
My mother has had some significant shoulder problems this year — frozen-shoulder-esque, but with some odd signals that have made that diagnosis a little uncertain (as it so often is). She recently got some imaging done. The results were noteworthy in two ways.
First, the report literally and laughably has a question mark next to the heading “history,” as in the clinical history, the story of the case. In musculoskeletal medicine, for almost anything more subtle than a major fracture, imaging is routinely futile or misleading, a fire hose of red herrings and ambiguity— and that’s with the clinical context! Without it? Fuhgeddaboudit.
In this case, of course, my mother discussed the results with her physician, and he did know the clinical history, but it’s still a bit appalling: “history” is a standard part of radiology reports for a reason.
And we’re about to see one of those reasons demonstrated rather well.
The second bizarre thing on the report
The magic flesh-penetrating sound waves revealed …
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… a nearly perfect left shoulder, and a right shoulder with an almost entirely ruptured biceps tendon: “only a few intact fibers.” Which was a mirror image of the clinical reality.
My mother has left shoulder trouble. The right feels perfect.
So what is going on?
Two main explanations for a reverse report
Almost everyone will underestimate the likelihood of the second.
The report has it backwards, and the ruptured tendon is actually on the left, the same side as my mom’s pain. No one knows the true rate of these kinds of errors, but I promise you it’s non-zero. They definitely happen. And this the first, best reason why the clinical history matters to the radiologist. If the reporting physician had known “left shoulder pain and restricted ROM,” he would have been far more likely to notice the reversal on the report.
The report is not backwards, but the state of tissue simply has startlingly little to do with pain and function, to a degree that people find hard to believe.
This is true especially in the shoulder, a complex and “temperamental” joint (and we see the same pattern in other complex areas like the neck and lower back). The mirror image here makes this particular disconnect rather glaring. But clear examples like this are the tip of an iceberg.
The iceberg of less obviously misleading imaging
For every obvious case like this, where the imaging picture is at odds with the clinical picture, there are probably many cases that are much less obvious. For instance, the results often show something that only awkwardly and imperfectly explains the clinical problem. It’s not a great fit, but you can make it fit. For instance, my mother’s symptoms could be explained by a ruptured biceps tendon… but not well. If the scan showed a ruptured tendon on her painful side, it would be very tempting to say, “Well, the symptoms aren’t quite right for a torn tendon, but that’s got to be it. I mean look at that thing!”
Or worse still: the symptoms do fit what is shown, but the relationship isn’t actually causal. A perfect red herring.
And this is the more profound reason why imaging results without clinical context are so problematic. You really cannot diagnose much of anything based on pictures alone. You need to know what’s happening with the actual patient! Imagine that!
Equating pictures with problems (relentlessly)
When my mother discussed this with her physician, he decisively equated the imaging results with a “problem” — ignoring the clinical history that he knew.
“But I don’t have any problem on my right,” my mother protested. “It’s entirely a left-side issue.”
He couldn’t let it go: he ignored what she was actually experiencing, and started troubleshooting a nonexistent clinical problem on the other side of her body, because he was ignorant of the notorious unreliability of objective evidence in this realm of medicine. Far too many healthcare professionals still think of musculoskeletal medicine as “simple” and “mechanical.” They have no idea how many other weird factors are involved, and so they have this powerful tendency to assume that obvious structural defects must mean clinical trouble (very “well there’s your problem”).
This tendency is so strong that many professionals will do it even when the clinical problem literally doesn’t exist. Amazing.
Imaging is amazing stuff. But it’s not magic: it cannot diagnose things on its own.