Beyond the non-contrast CT: the infarct core (DWI or CT perfusion rCBF), the hypoperfused tissue at risk (Tmax), the vessel occlusion on angiography, and the DWI–FLAIR mismatch that dates a wake-up stroke — each answers a thrombectomy or thrombolysis question.
Orient first
- Thrombectomy trials in the late window selected patients by a small core and a large mismatch (verify the current thresholds and guidelines).
- On MRI, a lesion visible on diffusion but not yet on the fluid-attenuated series suggests onset within ~4.5 h in wake-up stroke.
- Perfusion thresholds are software-specific; the report names the package and its default thresholds.
Acquire the study
- DWI/ADC, FLAIR, SWI, MRA (TOF or contrast-enhanced), DSC perfusion.
The manoeuvre
- DWI/ADC: infarct core volume in ml.
- FLAIR: is the DWI lesion visible? DWI–FLAIR mismatch dates it.
- SWI: susceptibility vessel sign (clot) and microbleeds.
- MRA: occluded segment (ICA, M1, M2, basilar).
- Perfusion Tmax > 6 s volume and mismatch ratio against the DWI core.
What confirms it
- A DWI or perfusion-defined core with a documented large-vessel occlusion and mismatch.
What licenses you to exclude it
- A normal DWI does not fully exclude stroke — small brainstem infarcts can be negative early.
The classic misread
- Calling reversible DWI lesions after early recanalisation core.