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Difficulty: MediumInterpreting Imaging Results

A 54-year-old right-handed woman is brought to the emergency department by emergency medical services 3 hours after the sudden onset of profound left-sided weakness, facial asymmetry, and slurred speech. On physical examination, her blood pressure is 175/95 mm Hg, and her pulse is 88/min and irregularly irregular. Neurological evaluation reveals a dense left hemiparesis, left-sided sensory loss, and left-sided hemineglect. The clinical team suspects an acute ischemic cerebrovascular event and initiates a rapid stroke code response. Arrange the following diagnostic imaging modalities in the correct chronological sequence utilized to evaluate this patient, establish the diagnosis, and guide acute reperfusion therapies.

  1. 1Non-contrast computed tomography (NCCT) of the head
  2. 2Computed tomography angiography (CTA) of the head and neck
  3. 3Computed tomography perfusion (CTP) imaging
  4. 4Magnetic resonance imaging (MRI) of the brain with diffusion-weighted imaging (DWI)

Answer

The correct chronological sequence for interpreting neuroimaging in this acute stroke scenario is: Non-contrast CT of the head, followed by CT angiography of the head and neck, then CT perfusion imaging, and finally MRI of the brain with diffusion-weighted imaging.
The acute stroke imaging cascade is explicitly designed to rapidly triage patients for time-sensitive reperfusion therapies. The absolute first step is a non-contrast CT to exclude intracranial hemorrhage, a definitive contraindication to thrombolysis. Immediately following, CT angiography is performed to identify large vessel occlusions amenable to mechanical thrombectomy. CT perfusion is then utilized to quantify the volume of irreversibly infarcted tissue versus salvageable penumbra. Finally, an MRI with diffusion-weighted imaging is obtained in the subacute phase to definitively map the completed infarct for prognostication and secondary prevention planning.

Step-by-Step Solution

1
Exclude acute intracranial hemorrhage.
NCCT of the head is performed and interpreted as the first immediate action.
Administration of intravenous thrombolysis is absolutely contraindicated if intracranial bleeding is present. NCCT is the fastest and most universally available modality to verify this.
2
Identify anatomical targets for endovascular intervention.
CTA of the head and neck is evaluated.
Once bleeding is ruled out, identifying a proximal large vessel occlusion (LVO) is necessary to determine if the patient is a candidate for mechanical thrombectomy.
3
Assess tissue viability and hemodynamics.
CTP imaging is analyzed.
Perfusion imaging differentiates the irreversibly infarcted ischemic core from the critically hypoperfused but salvageable penumbra, confirming the potential benefit of intervention.
4
Confirm final infarct characteristics subacutely.
MRI of the brain with DWI is obtained later in the hospital course.
MRI is highly sensitive for delineating the exact anatomical extent of the completed stroke, providing crucial information for long-term management, secondary prevention, and prognostication.

Key Concept

Sequential neuroimaging in acute ischemic stroke to establish eligibility for thrombolysis and mechanical thrombectomy.
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Interpreting Imaging Results

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