Which imaging modality is used to identify the salvageable penumbra in acute stroke?

Which imaging modality is used to identify the salvageable penumbra in acute stroke?

• A. Magnetic resonance diffusion imaging
• B. Plain CT
• C. Duplex ultrasound
• D. Computed tomography perfusion imaging

Answer: (D)

When thinking about salvageable brain tissue after an acute stroke, the key idea is to map areas with reduced blood flow that are still viable (the penumbra) versus tissue that has already sustained irreversible damage (the core). Imaging that measures cerebral perfusion directly reveals this distinction. CT perfusion does this by evaluating parameters such as cerebral blood flow, cerebral blood volume, and time-to-maximum. In the affected region, you look for a perfusion deficit—areas with delayed blood arrival and reduced flow—but with preserved blood volume compared to the infarct core. The mismatch between the perfusion abnormality and the infarct core indicates tissue at risk that could be saved with reperfusion therapy. This capability makes CT perfusion a practical and widely used tool in acute stroke to guide treatment decisions, including eligibility for thrombectomy. By contrast, plain CT lacks perfusion data, diffusion MRI highlights the already infarcted core, and duplex ultrasound evaluates vessel anatomy and flow rather than tissue viability.

When thinking about salvageable brain tissue after an acute stroke, the key idea is to map areas with reduced blood flow that are still viable (the penumbra) versus tissue that has already sustained irreversible damage (the core). Imaging that measures cerebral perfusion directly reveals this distinction. CT perfusion does this by evaluating parameters such as cerebral blood flow, cerebral blood volume, and time-to-maximum. In the affected region, you look for a perfusion deficit—areas with delayed blood arrival and reduced flow—but with preserved blood volume compared to the infarct core. The mismatch between the perfusion abnormality and the infarct core indicates tissue at risk that could be saved with reperfusion therapy. This capability makes CT perfusion a practical and widely used tool in acute stroke to guide treatment decisions, including eligibility for thrombectomy. By contrast, plain CT lacks perfusion data, diffusion MRI highlights the already infarcted core, and duplex ultrasound evaluates vessel anatomy and flow rather than tissue viability.