When is CT imaging unnecessary?

Julian Dobranowski, MD, is a professor and chair of the Department of Radiology at McMaster University and chief of diagnostic imaging at Niagara Health.

What are the most common reasons for unnecessary computed tomography (CT) scan requests and how to avoid them?

The question of unnecessary CT scans is a challenging question too, because there are various factors that go into decision making about whether an examination is necessary or not.

An examination should be performed if we expect that there’s going to be a benefit to the patient, and that benefit has to outweigh any negative effects of that examination itself.

Where I find that there’s overordering of these tests is if the physician ordering the test is out of their regular realm of comfort. So, if we have specialists in respirology ordering CTs of the thorax, then we’re pretty comfortable that, with their experience, the test is going to be necessary. Somebody who has no experience in respirology, who is ordering tests that are related to respirology is [a setting] that we find challenging.

We’re also finding that after coronavirus disease 2019 (COVID-19), imaging is becoming almost a surrogate for the clinical examination. Patients who are coming to the emergency department, a lot of them, have a CT done in lieu of other examinations. Part of that is for detection of disease, but also to expedite the patient’s stay in the emergency department because emergency departments have seen an unprecedented total number of patients coming through them.