Magnetic resonance imaging and computed tomography utilization trends in an academic ED

The objective of this study is to examine the annual utilization trends of emergency department (ED)-ordered magnetic resonance imaging (MRI) and computed tomography (CT) at an urban academic hospital from 2007 to 2011. We hypothesized that MRI and CT use would increase annually over the study period.

This was a retrospective observational study of ED encounters between January 1, 2007, and December 31, 2011. All patients seen by a provider were identified, and demographics were abstracted. Type of CT and/or MRI examination, clinical indication, and final disposition were collected. Records of patients with an ED-ordered MRI were also examined for presence of a CT within ±3 days of their encounter date. Unadjusted linear regression was used to assess for differences among years for both CT and MRI. Secondary outcomes were descriptively summarized.

A total of 7089 MRI (20 per 1000) and 85,673 CT (243 per 1000) examinations were ordered over a 60-month period. Computed tomography use decreased significantly (P=.021). Magnetic resonance imaging use significantly increased (2.2 per 1000 ED visits each year, P=.005). Magnetic resonance imaging of the head was ordered most frequently (10.7 per 1000). The overwhelming majority of MRI images were completed for acute neurologic/behavioral problem. Of patients with an MRI completed, 89.4% had a CT completed within 3 calendar days with most of the CT examinations (81%) completed during the encounter.

There was a steady increase in MRI testing in our academic ED, with most MRIs ordered for acute neurologic or behavioral changes. There was a corresponding decreasing trend for CT scans.