## Clinical Context This patient presents within the thrombolytic window (2.5 hours < 4.5 hours) with acute ischemic stroke symptoms and a normal non-contrast CT (ruling out hemorrhage). The clinical presentation is consistent with acute ischemic stroke. ## Rationale for Correct Answer **Key Point:** In acute ischemic stroke within 4.5 hours of symptom onset, intravenous thrombolysis (alteplase) should NOT be delayed for advanced imaging if non-contrast CT excludes hemorrhage and there are no contraindications. **High-Yield:** Non-contrast CT is the standard first imaging modality in acute stroke to rule out hemorrhage. A normal CT in the setting of acute ischemic stroke symptoms is sufficient to proceed with IV thrombolysis without waiting for MRI. **Clinical Pearl:** The goal is "time is brain"—every minute of delay increases infarct volume. MRI, while more sensitive for acute ischemia (DWI shows restricted diffusion within minutes), should NOT delay thrombolysis in the acute window. ## Why Immediate tPA is Correct - Patient is within the 4.5-hour IV thrombolysis window - Non-contrast CT excludes hemorrhage (primary safety concern) - No contraindications mentioned in the stem - Earlier reperfusion = better neurological outcome - Alteplase is indicated and should be administered without delay ## Management Algorithm ```mermaid flowchart TD A[Acute stroke symptoms]:::outcome --> B{Time since onset?}:::decision B -->|< 4.5 hours| C[Non-contrast CT]:::action C --> D{Hemorrhage present?}:::decision D -->|No| E[Check IV thrombolysis eligibility]:::decision D -->|Yes| F[Contraindicated for IV thrombolysis]:::urgent E -->|Eligible| G[Administer IV alteplase immediately]:::action E -->|Ineligible| H[Supportive care, consider other options]:::action G --> I[Monitor for reperfusion/complications]:::outcome B -->|> 4.5 hours| J[Consider mechanical thrombectomy window]:::decision ``` 
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