The Case Against Quantitation

Making healthcare more objective and precise promises to increase efficiency and reduce costs — the key ingredients of value medicine. At the University of Pennsylvania, the Penn Center for Innovation has developed an image quantification tool that might help achieve both goals.

Called the Automated Anatomy Recognition (AAR) system, it localizes and delineates cancer in multiple body regions using magnetic resonance imaging (MRI), computed tomography (CT) and positron emission tomography/computed tomography (PET/CT) images. When applied to radiation therapy planning, AAR can reduce the time needed to delineate organs from several hours to less than 5 minutes. Successes like this fuel speculation that quantitation may be broadly applied to make medicine more efficient and effective. But quantitation is a means to an end, typically a highly focused end.

Essentially quantitation in medical imaging defines a range of numerical values associated with a pathology. At best, it adds information that may be used to streamline analyses or increase the certainty of conclusions. At worst, it creates the illusion that diagnosis can be reduced to numbers. And therein lies the potential problem. 

It is all too easy to assign to quantitation greater value than it deserves. It cannot simply be extended to all aspects of medical interpretation. No one has suggested doing so closely. And for good reason.

Human Experience

When interpreting exams, radiologists draw from their experience. They may consider quantitative measures, interpreting them in a broader context.

The very basis of enterprise imaging is to provide this context to referring physicians who can see radiological images and to radiologists who can call up lab results and path reports. If quantitative imaging adds more information, great. But it is human nature to follow the shortest path between two points; to take the path of least resistance; to delegate to machines what might better be accomplished under our own power.

A few years ago I saw my neighbor across the street riding his lawn tractor down the driveway to get his mail. He laughed when he saw me watching, answering, “Never do what a machine can do.”

It turned out not to be causative that he had just finished cutting the backyard and was on lawn tractor; or that the ride to the mailbox might have been done on a whim. A few days later I soon saw him driving his lawn tractor over to his next-door neighbor. Never mind that he could walk faster than his tractor could drive. Never mind that the walk would have done him good. These thoughts were non-starters for my neighbor.

Ride To Nowhere

And so it goes with machines. If they reduce labor or simplify complex tasks, they are sure to be a hit. Unfortunately what might be left out of the equation is whether the end result is superior to what would have been achieved more conventionally.

We are at a time when radiologists are being pushed to take on a bigger role in healthcare. In a word, they are vying for “more.” More opportunity to make more of an impact by becoming more involved in patient care — not just in diagnostic work-ups but therapy planning and treatment assessment. And it is happening.

At the NYU Langone Medical Center, radiologists are making morning rounds — virtual ones, to be precise — communicating with medical staff over the center’s wireless network, sharing images and insights, and improving patient care. As told in a Wall Street Journal article, one such interaction led to the discovery of a defect in the hip of a six-month-old patient operated on for a congenital heart defect.

Making this possible was the human ability to see the whole patient, to see what otherwise might not have been seen, if the focus been on just one aspect of the patient’s care.

Radiologists are more familiar than any other medical specialist with the imaging options available for patient assessment and how those options might be utilized. An MR image might tell enough of the story to draw a conclusion. Or MR results might be fused with those coming from a PET scan to see the functional and anatomical together. Or MR might be used in real-time to guide radiation therapy … or to guide a neuro intervention. 

Once the lead leveraging their skills, radiologists go well beyond simply interpreting images, exemplifying the limits of quantitation.

The phrase “to err is human” has led to the pursuit of increasingly precise and objective means of analysis. And that’s good. Quantitation is another arrow in the quiver of precision medicine. But radiologists must be called upon to consider which arrow to pull from that quiver. Knowing that — and when to fire those selective arrows — has never been more important.

Hanging in the balance are patient welfare and lower healthcare costs. This is happening at a time when American medical institutions are beginning to creak under the healthcare needs of an aging population.

How well these institutions hold up may depend on how well healthcare providers choose from the sources of information available to them — and how well the resulting information is managed. The answers will not to be found worshiping at the digital altar.

In our zeal to be more precise, we must not put at risk the unique human ability to perceive what cannot be exactly defined — or quantified.

Editor's note: This is the third blog in a four-part series on patient centricity. The first blog, “Value Medicine: Radiology’s Big Chance,” can be found here. “What To Do About The Draper Effect” can be found here.