A 65-year-old male suddenly develops left-sided weakness and slurred speech. He arrives at the emergency department within 30 minutes of symptom onset. Which of the following is the most appropriate initial imaging modality to differentiate between ischemic and hemorrhagic stroke?

Explanation

Non-contrast CT brain is the most appropriate initial imaging modality for acute stroke. It is rapidly available, highly sensitive for detecting intracranial hemorrhage (which is a contraindication for thrombolytic therapy), and can rule out other stroke mimics. While MRI with diffusion-weighted imaging (DWI) is more sensitive for detecting early ischemic changes, CT is faster and crucial for the immediate decision-making regarding thrombolysis by ruling out hemorrhage. CT angiography is used to evaluate cerebral vasculature after initial CT, and carotid duplex ultrasound evaluates carotid arteries but not the brain parenchyma.