A 58-year-old man from Delhi presents to the emergency department with acute onset right-sided weakness and speech difficulty that began 2 hours ago. Blood pressure is 165/95 mmHg, heart rate 92/min. Non-contrast CT head shows no hyperdensity. MRI brain with DWI-weighted imaging performed 3 hours after symptom onset reveals multiple acute infarcts in the left middle cerebral artery (MCA) territory with restricted diffusion. What is the most appropriate next step in management?

Explanation

## Clinical Context This patient presents with acute ischemic stroke in the MCA territory within the thrombolytic window (3 hours from onset). The non-contrast CT is negative for hemorrhage, and DWI-MRI confirms acute ischemia. ## Imaging Interpretation **Key Point:** DWI-weighted MRI hyperintensity with corresponding ADC hypointensity is the gold standard for detecting acute ischemic stroke within minutes of symptom onset, superior to conventional CT imaging. **High-Yield:** The presence of multiple acute infarcts in a single vascular territory (MCA) raises suspicion for large vessel occlusion (LVO), which carries a worse prognosis and may benefit from mechanical thrombectomy even beyond the standard thrombolytic window if imaging criteria are met. ## Management Algorithm ```mermaid flowchart TD A[Acute ischemic stroke, DWI+ within 3 hrs]:::outcome --> B{Large vessel occlusion suspected?}:::decision B -->|Yes - obtain CTA first| C[CT angiography head/neck]:::action B -->|No| D[Thrombolysis eligible?]:::decision C --> E{LVO confirmed?}:::decision E -->|Yes| F[Mechanical thrombectomy]:::action E -->|No| G[Thrombolysis + aspirin]:::action D -->|Yes| H[IV alteplase]:::action D -->|No| I[Antiplatelet monotherapy]:::action F --> J[Reperfusion achieved]:::outcome H --> J ``` ## Rationale for CT Angiography 1. **LVO Detection:** CTA is rapid, non-invasive, and has >95% sensitivity for detecting occlusion of proximal vessels (ICA, MCA M1/M2 segments). 2. **Thrombectomy Candidacy:** Patients with LVO benefit from mechanical thrombectomy even in the 3–24 hour window if imaging criteria (DAWN, DEFUSE 3 trials) are met. 3. **Thrombolysis Optimization:** If CTA shows no LVO, IV thrombolysis can proceed immediately; if LVO is present, thrombectomy becomes the priority. 4. **Standard Protocol:** Current AHA/ASA guidelines recommend CTA or MRA in all acute stroke patients to stratify for endovascular therapy. **Clinical Pearl:** Multiple acute infarcts in one vascular territory is a red flag for embolic occlusion of a large proximal vessel rather than small-vessel disease. **Tip:** Do not delay thrombolysis while awaiting CTA if the patient is within the IV tPA window and has no contraindications — CTA should be done in parallel or immediately after IV tPA initiation if LVO is suspected.