On non-contrast head CT, which finding helps differentiate ischemic from hemorrhagic stroke in the acute setting?

• A. Ischemia is always visible on non-contrast CT in the first hours.
• B. Hemorrhage appears as an acute hyperdense area indicating bleed; ischemia may be CT-negative initially.
• C. CT always shows ischemia immediately.
• D. CT cannot help before thrombolysis.

Answer: (B)

In the acute setting, non-contrast CT’s main job is to quickly tell if there’s bleeding. Fresh blood appears as a bright, hyperdense area, signaling an intracranial hemorrhage. By contrast, early ischemic brain tissue often looks normal on non-contrast CT; the initial signs of ischemia can be subtle or absent within the first hours. So seeing a hyperdense region points to hemorrhage, while the absence of a hyperdense bleed does not rule out ischemia, especially early on. This distinction is crucial for therapy decisions, because thrombolytics are avoided if hemorrhage is present.