Ischemic Stroke — CT and MRI

A 62-year-old man with hypertension and diabetes presents with acute onset left hemiparesis. Non-contrast CT head is normal. MRI with DWI sequence shows restricted diffusion in the right middle cerebral artery (MCA) territory. What is the most common site of arterial occlusion in acute ischemic stroke?

A 58-year-old man from Delhi presents with acute left-sided weakness and speech difficulty of 2 hours duration. Non-contrast CT head is normal. Regarding the imaging findings in acute ischemic stroke, all of the following statements are true EXCEPT:

In acute ischemic stroke, which finding on conventional CT brain within the first 6–12 hours indicates irreversible infarction and is associated with poor prognosis?

A 58-year-old man from Delhi presents to the emergency department with acute onset left-sided weakness and slurred speech of 2 hours duration. Blood pressure is 165/95 mmHg, heart rate 88/min regular. Non-contrast CT head shows no hyperdensity. MRI brain performed 3 hours after symptom onset reveals restricted diffusion in the right middle cerebral artery territory on DWI sequences with corresponding low signal on ADC maps. What is the most appropriate next step in management?

A 62-year-old man presents to the emergency department with acute onset left-sided weakness and speech difficulty of 2 hours duration. Non-contrast CT head is normal. Which investigation is most appropriate to confirm acute ischemic stroke and guide thrombolytic therapy?