penumbra
In stroke imaging, the region of brain tissue that is hypoperfused but not yet irreversibly damaged, representing potentially salvageable tissue.
Full Definition
The ischemic penumbra refers to brain tissue surrounding an infarct core that has reduced blood flow but remains metabolically active and potentially viable. This concept is central to acute stroke management, as the penumbra represents the therapeutic target for reperfusion therapy. Imaging-based identification of penumbra typically relies on mismatch between diffusion abnormalities (core) and perfusion deficits (core plus penumbra). The presence of significant penumbra can extend treatment windows beyond traditional time limits and guide clinical decision-making in acute stroke care.
Usage
Usage note: Always specify 'ischemic penumbra' in clinical contexts to avoid confusion with other uses of 'penumbra.'
In Context
- "The large penumbra identified on CT perfusion supported mechanical thrombectomy despite delayed presentation." — Stroke intervention report
- "DWI-PWI mismatch indicated substantial penumbra available for salvage with reperfusion therapy." — Acute stroke imaging interpretation