What is the best radiographic test to confirm a diagnosis of acute ischemic stroke in a patient with sudden onset of right-sided weakness and neurological deficits?

Best Radiographic Test for Acute Ischemic Stroke

Non-contrast CT scan of the head is the best radiographic test to confirm the diagnosis of acute ischemic stroke in this patient presenting with right-sided weakness and neurological deficits.

Rationale for Non-contrast CT as First-line Imaging

The patient presents with classic symptoms of acute stroke including:

• Sudden onset right arm weakness
• Sensory deficits
• Communication difficulties
• Hyperreflexia
• Hypertension (188/104)
• Onset within 2 hours (well within treatment window)

Guidelines Supporting Non-contrast CT:

1. Primary Goal of Immediate Imaging

   • The primary goal of imaging in acute stroke is to distinguish between hemorrhagic and ischemic stroke 1
   • Non-contrast CT can rapidly exclude hemorrhage, which is essential before considering thrombolytic therapy 1

2. Time Considerations

   • For patients within the treatment window for IV thrombolysis (0-4.5 hours), non-contrast CT is recommended as the first-line imaging study 1
   • The American Heart Association/American Stroke Association guidelines state that "CT or MRI of the brain is recommended to confirm the diagnosis of symptomatic ischemic cerebral vascular disease" 1

3. Practical Advantages

   • CT is more widely available, faster to perform, and less susceptible to motion artifacts compared to MRI 1
   • Emergency treatment should not be delayed to obtain multimodal imaging studies 1

Why Other Options Are Not Preferred Initially:

• CT with IV contrast: Not recommended as initial imaging in acute stroke as it does not provide additional critical information for immediate management and may delay treatment 1

• MRI of the brain: While MRI (especially with diffusion-weighted imaging) is more sensitive for detecting early ischemic changes, it takes longer to perform and may not be immediately available, potentially delaying treatment 1, 2

• 2D echocardiogram: This is useful for identifying cardiac sources of embolism but is not the initial test to confirm stroke diagnosis 1

• EEG: Not indicated for initial stroke diagnosis; used primarily for evaluating seizure activity 1

Clinical Management Algorithm

1. Immediate Non-contrast CT scan

   • Exclude hemorrhage
   • Assess for early signs of infarction
   • Can be completed rapidly without delaying potential thrombolysis

2. After Initial CT

   • If CT is negative but clinical suspicion remains high, consider MRI with diffusion-weighted imaging 1
   • Vascular imaging (CT angiography or MR angiography) should be performed to evaluate the mechanism of stroke and assess risk for future stroke 1

3. Additional Imaging Based on Initial Findings

   • If large vessel occlusion is suspected, proceed to CT angiography to identify potential targets for endovascular therapy 2
   • Consider MRI for better visualization of posterior circulation strokes, which may be missed on CT due to beam hardening artifacts 2

Important Considerations

• The presence of early infarct signs on CT (even if extensive) does not preclude treatment with IV thrombolysis if the patient is within the 3-hour treatment window 1

• Serial head CT within the first 24 hours can be useful to evaluate for hemorrhagic transformation, especially in patients with neurological deterioration 1

• For patients with TIA or resolved symptoms, MRI with diffusion-weighted imaging is preferred over CT due to higher sensitivity 1, 3

Non-contrast CT remains the cornerstone of initial imaging in acute stroke evaluation due to its speed, availability, and ability to exclude hemorrhage before time-sensitive treatment decisions are made.