Decadal Trends in Emergency Department Head and Neck CTA Utilization: A Comprehensive Analysis of Volume, Trauma, and Clinical Severity.

BACKGROUND AND PURPOSE: Neuroradiology services report rising ED CTA head and neck demand. Although late-window thrombectomy trials increased interest in perfusion-based selection, relative growth of CTA head and neck versus CT perfusion (CTP), and how these trends compare with overall neuro-ED imaging volume, ED throughput, and coverage periods, remains incompletely characterized. We evaluated decade-long neuro-ED imaging trends at a tertiary care academic medical center. MATERIALS AND METHODS: Retrospective observational study including all neuroradiology ED examinations from two hospital ED sites from fiscal years (FY) 2016-2025. Primary outcomes included annual CTA head, CTA neck, and CTP volumes; their proportions of total neuro-ED imaging; examinations per ED encounter; and (CTA head + CTA neck)-to-CTP ratio. Encounter-normalized trends for FY2016-FY2025 were modeled using negative binomial regression. Coverage-period distribution was assessed using CTA exam-code rates per hour during regular versus on-call hours. Secondary clinical-context sub-analyses assessed baseline National Institutes of Health Stroke Scale (NIHSS) and large language model (LLM)-assisted report abstraction for indications and large vessel occlusion (LVO) yield. RESULTS: Across 303,753 neuro-ED examinations, ED encounters increased modestly from FY2016 to FY2025 (+11%, 108,948 to 121,288), while neuro-ED imaging more than doubled (+111%, 20,087 to 42,398). Combined CTA head and neck examination-code volume increased 8.5-fold (745 in FY2016 to 6,317 in FY2025). Share of CTA head and neck rose from 3.7% (745/20,087) to 14.9% (6,317/42,398) of neuro-ED imaging. Encounter-normalized utilization increased significantly for CTA head and neck (incidence rate ratio [IRR] per FY 1.22 and 1.20, respectively; both p<0.001) but did not change significantly for CTP (IRR 1.00). (CTA head + CTA neck)-to-CTP ratio increased from 4.2 in FY2018 to 9.9 in FY2025. CTA rates per hour increased during both regular and on-call coverage without differential growth. Secondary exploratory analyses suggested increasing CTA use in NIHSS 0 presentations and declining LVO yield. CONCLUSIONS: Over a decade at a tertiary academic center, ED CTA head and neck volumes rose sharply, outpacing ED throughput, overall neuro-ED imaging growth, and CTP utilization. CTA demand increased similarly across regular and on-call periods, underscoring escalating after-hours operational burden and implications for neuroradiology coverage models.