Medical imaging and the dangers of the ‘illusion of knowing’

Too often, even the most advanced diagnostic visuals send radiologists, referrers and patients on so many medical fool’s errands.

A new general-audience book makes a compelling case that all three groups of stakeholders would do better by learning how to live with ambiguity. 

Even in the face of positive findings. Even when the uncertainty verges on the terrifying. And even after adjusting for defensive approaches that protect docs from lawsuits and patients from probable harm.

The book is Nonsense: The Power of Not Knowing. Its author, Jamie Holmes, is a fellow at the nonpartisan, nonprofit think tank New America. His work is selling well and drawing attention, making Holmes something of an ambiguity evangelist.

The book’s sweep is much broader than healthcare, but it’s got a chapter titled “Overtested USA” that takes modern medical imaging to task.

“Healthcare technologies, especially imaging technologies, may be particularly tempting solutions to medical dilemmas because they promise to let us see previously hidden parts of the human body,” Holmes writes. “But the body and mind are not machines that we can simply hook up to a computer to determine what’s wrong. Neither strictly follows … simple cause-and-effect rules.”

After summarizing numerous studies focused on various imaging modalities, Holmes shows that autopsies performed before and after the introduction of ultrasound, CT and radionuclide scanning have revealed that diagnostic accuracy hasn’t seemed to improve.

Using as a bracing example lawyers’ increasing use of neuroimaging to try to keep murderers off of death row, he references a Duke University database showing that such evidence was considered in at least 1,600 cases between 2004 and 2012.

Holmes writes, “One San Diego defense attorney boasted of introducing a PET scan as evidence of his client’s moral innocence: ‘This nice color image … documented that this guy had a rotten spot in his brain. The jury glommed onto that.’”

Holmes then recounts the ironic story of James Fallon, the UC-Irvine neuroscientist who famously had himself PET scanned only to find that his prefrontal lobe looked no different than those of the psychopathic killers he’d been studying.

Neuroimaging for criminal forensics surely isn’t a perfect example of medical imaging run amok.

And Holmes allows that medicine has used imaging technologies to great benefit.

However, he compellingly stresses, it also has used them to create false and expensive expectations of certainty.

“No one can blame practitioners or policymakers for their enthusiasm over new technological tools,” he writes. “But just as criminologists would be wiser to focus on the social—rather than biological—conditions that spur violence, physicians are usually better off treating the patient, not the scan.”

Most diagnoses, he insists, can be made by chatting.

“New ways of seeing aren’t necessarily clearer ways of seeing,” writes Holmes, “and sometimes the illusion of knowing is more dangerous than not knowing at all.”

Of course, that’s easy to say when it’s not your image the radiologist is red-flagging. Or your practice the patient’s attorney is going after.

Jamie Holmes’s “power of not knowing” has its upsides, no doubt. But under what conditions should one expect its cures to justify its costs? 

-Dave Pearson 
Senior Writer