Which imaging modality is used to assess the penumbra in acute ischemic stroke?

Which imaging modality is used to assess the penumbra in acute ischemic stroke?

• A. CT perfusion imaging
• B. MRI diffusion-weighted imaging
• C. FDG-PET
• D. Ultrasound

Answer: (B)

Penumbra in acute ischemic stroke refers to tissue that is underperfused but still viable and can be saved with timely reperfusion. To identify this at-risk area, we rely on perfusion imaging that measures parameters such as cerebral blood flow, cerebral blood volume, and mean transit time, and we compare these with diffusion imaging, which pinpoints tissue that has already infarcted. The telltale sign of penumbra is a mismatch: areas with perfusion deficit but no diffusion restriction. Diffusion-weighted imaging alone highlights the damaged core, not the at-risk region. Among the options, CT perfusion imaging is the practical, rapid modality used in the emergency setting to map perfusion deficits and delineate penumbra (MRI perfusion can be used as well, but is less immediate). FDG-PET and ultrasound don’t provide the same direct assessment of penumbra in the acute workflow.

Penumbra in acute ischemic stroke refers to tissue that is underperfused but still viable and can be saved with timely reperfusion. To identify this at-risk area, we rely on perfusion imaging that measures parameters such as cerebral blood flow, cerebral blood volume, and mean transit time, and we compare these with diffusion imaging, which pinpoints tissue that has already infarcted. The telltale sign of penumbra is a mismatch: areas with perfusion deficit but no diffusion restriction. Diffusion-weighted imaging alone highlights the damaged core, not the at-risk region. Among the options, CT perfusion imaging is the practical, rapid modality used in the emergency setting to map perfusion deficits and delineate penumbra (MRI perfusion can be used as well, but is less immediate). FDG-PET and ultrasound don’t provide the same direct assessment of penumbra in the acute workflow.