The problem with determining the value of a medical technology purely on the basis of scientific fact is that it ignores how health decisions are often made. You might come up with the correct answer but not the right one.

In the case of coronary calcium screening, the correct answer is probably that it accurately identifies patients with coronary artery disease, but has not yet been proven to add substantially to what common risk factors can predict about the likelihood of having a heart attack (see our cover story on page 48).

The right answer for many people, however, may be that a picture speaks a thousand words. In my former life as a clinical nutritionist, I noticed that men who were recovering from a heart attack—guys who had spent every lunch hour for the previous decade at Burger King—would hang on my every word. Having been shocked, finally, into paying attention to their health, they were suddenly keen to learn all about appropriate selections from the salad bar.

Can coronary calcium screening serve the same purpose? Several studies have suggested that patients who undergo coronary calcium screening are far more likely to lose weight, reduce their dietary fat and cholesterol intake, and adhere to medication regimens prescribed by their physicians.

It may just be that patients who are willing to drop $500 to find out what’s lurking in their arterial walls are more predisposed to making heart-healthy lifestyle changes than the average person. Or it may be that seeing bright calcium spots is sufficiently shocking to do what no lecture from a physician can.

Does that make coronary calcium screening good medicine? Maybe, but maybe not. Patients are deciding the future of this technology, and my bet is that whatever the scientific community says, they’ll continue to vote with their pocketbooks.

Ms. Carrington is the former editor of Health Measures and Telehealth Magazine.