ACR Appropriateness Criteria Facilitate Judicious Use of CT Angiography for Stroke Workup in the Emergency Department

Purpose: CT angiography (CTA) of the head and neck plays a key role in the evaluation of patients with stroke in the emergency department, particularly to evaluate for large-vessel occlusion and consider patients for mechanical thrombectomy. However, CTA is not always indicated and has various costs. The aim of this study was to examine the correlation between ACR imaging appropriateness recommendations and findings explanatory for stroke on CTA of the head and neck. Methods: CTA head and neck examinations of emergency department patients performed to evaluate for stroke between January 1, 2019, and June 30, 2019, were retrospectively reviewed. Patients with previously known acute infarct, with primary concern for or discovered hemorrhage, or being evaluated for trauma were excluded. Presenting symptoms were classified on the basis of the most recent ACR Appropriateness Criteria, into three categories: "usually appropriate" (UA), "may be appropriate" (MBA), or "usually not appropriate" (UNA). The percentage of examinations with findings explanatory for stroke were compared among the three groups using the Fisher exact test. Results: A total of 707 cases were reviewed, of which 317 were included; 199 fell into the UA category, 38 MBA, and 80 UNA. For UA, 57 of 199 CTAs (29%) had findings explanatory for stroke, compared with 1 of 38 (3%) in the MBA group (difference, 26%; 95% confidence interval, 13%-34%; P < .001) and 1 of 80 (1%) in the UNA group (difference, 27%; 95% confidence interval, 19%-35%; P < .001). Conclusions: ACR Appropriateness Criteria recommendations correlate with imaging findings explanatory for stroke and may guide the judicious use of CTA for suspected stroke workup.