Would you tell me, please, which way I ought to go from here?
That depends a good deal on where you want to get to.
I don’t much care where –
Then it doesn’t matter which way you go.
– Lewis Carroll

In the new world, payers will increasingly ask before reimbursing medical imaging: why did you bother finding out? This is why we must pay attention to clinical trials.

An instructive case is in the imaging of patients with chronic angina. Physicians have many choices: nuclear study, MRI, CT, echo and PET.

Choice obfuscates. Multiplicity leads to petty battles over which test is more superior. Is it a test with a sensitivity of 88% and specificity of 82% or a test with a sensitivity of 89% and a specificity of 81%?  Freud called this “narcissism of small differences.”

However, a more primal question has arisen.

Not which test is better, SPECT or stress MRI?

But why image patients with either?

Why do we image patients suspected to have narrowing of their coronary arteries?

To ensure that patients most likely to have obstructed arteries, and only they, undergo a coronary angiogram; a test which is invasive, expensive and risky.

Why put patients through a coronary angiogram? To determine their candidacy for revascularization, which is even more costly and risky.

Why revascularize coronary arteries? Because it makes people live longer than the alternative: medication.

That’s what we all thought until the COURAGE trial. Symptomatic patients with obstructed coronaries were randomized to stents and pills. Pills did just as well as stents (well, almost).

If stents are no better than pills, then why perform the angiogram? Why not start patients on medication and see their response?

Let’s move upstream. If there is no need for an angiogram, if there is nothing to gatekeep, what is the point of either SPECT or MRI? Again, why not start patients on medication and see their response?

The COURAGE trial left hope for stents. A subgroup analysis showed that patients who had benefited most from stents had the most amount of ischemia on nuclear imaging. Meaning that searching for ischemia could still have value.

The ISCHEMIA trial will determine whether that sub-group analysis ought to bail out the stent industry. In this multi-center trial, patients with chronic angina and proven ischemia will be randomized to revascularization or medication. Then a most primal of questions will be asked: any difference?

What if the ISCHEMIA trial says no benefit of stents over meds?

The ramifications will extend beyond the industry for stents, for which it will be only a partial death knell — stents will still be used for unstable angina. The findings could be portentous for upstream imaging such as SPECT. Imaging for ischemia could become an academic exercise. Constrained resources means that paying for knowledge for the sake of knowledge may not be CMS’s highest priority.

Imagers could find themselves having the following dialogue with patient’s physician:

Imager: “What will you do if the test shows ischemia?”

Clinician: “I will put the patient on pills.”

Imager: “What will you do if the test shows no ischemia?”

Clinician: “I will put the patient on pills, just to be sure.”

Do you see the problem here? If you know your way home of what use is a GPS?

Saurabh Jha is a radiologist. He can be reached on Twitter @RogueRad.  This article originally appeared in Radiology Business Journal.