Imaging suspected posterior circulation stroke in the emergency department: a practical modality-based review

Area of Science:

• Neurology
• Radiology
• Emergency Medicine

Background:

• Posterior circulation stroke (PCS) constitutes 20-25% of ischemic strokes.
• PCS is frequently misdiagnosed upon initial presentation in the emergency department (ED).
• Effective diagnosis relies on appropriate neuroimaging selection.

Purpose of the Study:

• To review established and emerging brain parenchymal and neurovascular imaging modalities for suspected PCS in the ED.
• To describe the technical principles, clinical roles, performance, limitations, and applications of each imaging modality.

Main Methods:

• Structured narrative review of imaging modalities for PCS evaluation.
• Prioritization of studies focusing on ED populations, posterior fossa infarction, society guidelines, and meta-analyses.
• Analysis of performance estimates, evidence base, and limitations for each modality.

Main Results:

• Non-contrast CT is insensitive for PCS (16-44%) but vital for excluding hemorrhage.
• CT angiography shows ~80% sensitivity for vertebrobasilar occlusion but only ~44% for overall PCS.
• MRI with DWI offers ~80% sensitivity, with high-resolution DWI approaching 90-95%; emerging modalities show variable sensitivity.
• Dual-energy CT (41-88%), portable low-field MRI (~69%), and accelerated MRI (80-95%) are under development.
• Performance data for novel techniques often stem from small, single-center studies with potential bias.

Conclusions:

• Diagnosing PCS requires careful selection and often a combination of imaging modalities.
• Imaging should be tailored to the specific clinical question (parenchyma vs. vasculature) and available resources.
• Further validation of emerging imaging techniques in larger cohorts is necessary.