What is the role of perfusion imaging in acute stroke triage?

• A. To measure blood pressure during stroke
• B. To identify the ischemic core and salvageable penumbra, guiding reperfusion therapy decisions
• C. To determine eligibility for anticoagulation only
• D. To identify hemorrhagic transformation

Answer: (D)

Perfusion imaging in acute stroke triage maps tissue viability to distinguish what tissue is already irreversibly damaged from what tissue is at risk but potentially salvageable. By measuring parameters such as cerebral blood flow, cerebral blood volume, and the timing of blood arrival (for example, Tmax on CT perfusion or similar metrics on MRI), clinicians can identify the ischemic core (dead or unsalvageable tissue) and the penumbra (salvageable tissue at risk). This mismatch between the core and the at-risk tissue guides decisions about reperfusion therapy, helping determine who stands to benefit from interventions like thrombectomy or thrombolysis, and sometimes even beyond typical time windows. Hemorrhagic transformation is typically detected with non-contrast CT or other hemorrhage-sensitive imaging to ensure safety before treatment; perfusion imaging isn’t the primary tool for identifying bleeding.