What is the purpose of CT angiography (CTA) in stroke evaluation?

• A. Non-contrast CT shows vessel status
• B. MR angiography shows vessels
• C. CTA visualizes cerebral vessels with arterial-phase contrast
• D. Ultrasound demonstrates cerebral vessels

Answer: (C)

CTA uses iodinated contrast injected into a vein and imaging during the arterial phase to produce a high-resolution map of the cerebral arteries. This quickly shows whether major vessels are open or occluded, where an occlusion lies, and the overall vessel anatomy. In acute stroke, identifying a large-vessel occlusion is crucial because it influences eligibility for endovascular thrombectomy and helps guide the treatment plan. CTA complements the non-contrast CT, which is used to rule out hemorrhage, and it’s typically faster and more readily available than MR-based vessel imaging. While MR angiography can visualize vessels, it’s slower and not as practical in the emergent stroke setting, and ultrasound can’t reliably assess intracranial arteries. So the main purpose of CTA is to visualize cerebral vessels with arterial-phase contrast to detect occlusions and inform urgent treatment decisions.