Background: There is increased awareness of radiation risks from computed tomography (CT) imaging in pediatric patients. In emergency departments (ED), evidence-based guidelines, improvements in imaging technology, and availability of non-radiating modalities have potentially reduced CT use. Objective: To evaluate changes over time and hospital variation in advanced imaging use. We hypothesized that CT use decreased, with a concomitant increase in ultrasound (US) and magnetic resonance imaging (MRI). Methods: This was a cross-sectional study of 26,082,062 visits to 32 United States’ pediatric EDs in the Pediatric Health Information System administrative database from January 1, 2009 through December 31, 2018. The primary outcome was the change in CT, US, and MRI rates from 2009 to 2018. Imaging for specific diagnoses were examined using All Patient Refined Diagnosis Related Groups (APR-DRG). Secondary outcomes included hospital admission and 3-day ED revisit rates, and ED length of stay (LOS). Results: ED encounters with any advanced imaging increased from 6.4% in 2009 to 8.7% in 2018 (Figure 1). Those with CT decreased from 3.9% to 2.9%, those with US increased from 2.5% to 5.8%, and those with MRI increased from 0.3% to 0.6% (test of trend, p<0.01 for all), The largest declines in CT were for concussion (-23.0%), appendectomy (-14.9%), ventricular shunt procedures (-13.3%), and headaches (-12.4%.) Drivers of increased use of non-radiating imaging modalities included US for abdominal pain (+20.3%) and appendectomy (+42.5%); and, MRI for ventricular shunt procedures (+17.9%) (test of trend, p <0.01 for all). Across the study period, ED’s varied widely in the use of US for appendectomy (median 57.5%, Interquartile range (IQR): 40.4%, 69.8%), and MRI (median 15.8%, IQR: 8.3%, 35.1%,) and CT (median 69.5%, IQR: 54.5%, 76.4%) for ventricular shunt procedures (Figure2). Overall ED LOS did not change, and hospitalization and 3-day ED revisit rates decreased over the study period. Conclusions and Relevance: Use of advanced imaging increased from 2009 to 2018. Although CT use declined, this was accompanied by a greater increase in use of US and MRI. There remains significant variation in practice and a need to standardize imaging use.

Trends in CT, US, and MRI for pediatric ED encounters 2009-2018

*all p values for trend <0.01

Hospital variation in advanced imaging by APR-DRGs 2009-2018

Boxplot distribution of the proportion of ED encounters with imaging. For each box, the horizontal line represents the median proportion, the dot represents the mean, and the upper and lower edges of the box represent the upper and lower quartiles, respectively. The whiskers indicate the range of values.