An 82-year-old woman is rushed to the emergency department by her family. She was eating breakfast 30 minutes ago when she suddenly developed left-sided facial droop, slurred speech, and left arm weakness. Her vital signs are stable, but her electrocardiogram shows atrial fibrillation. The stroke team is activated to evaluate her for potential thrombolysis and mechanical thrombectomy. Arrange the following imaging studies in the standard sequential order for the diagnostic workup of this acute presentation, starting with the immediate initial test.
- 1Non-contrast computed tomography (CT) of the head
- 2Computed tomography angiography (CTA) of the head and neck
- 3Magnetic resonance imaging (MRI) of the brain without contrast
Answer
The correct sequence is to first perform a non-contrast CT of the head, followed by a CTA of the head and neck, and finally an MRI of the brain at a later subacute stage.
The standard protocol for acute stroke imaging prioritizes speed and the rapid exclusion of contraindications for reperfusion therapy. A non-contrast CT is performed first to immediately rule out hemorrhage. Once hemorrhage is excluded, a CTA is indicated to evaluate for large vessel occlusions that would benefit from mechanical thrombectomy. Finally, an MRI is typically performed 24 to 48 hours later to clearly define the infarct size, location, and potential etiology, as it is the most sensitive modality but too time-consuming for the hyperacute triage phase.
Step-by-Step Solution
Key Concept
In acute stroke evaluation, imaging must be sequenced to prioritize rapid exclusion of hemorrhage (non-contrast CT) and identification of large vessel occlusion (CTA), while reserving more time-consuming definitive imaging (MRI) for later characterization.