In the context of 6-hour thrombectomy eligibility, which imaging finding supports selection when considering DW-MRI?

• A. Age >=18
• B. Occlusion of ICA or M1 MCA
• C. Mismatch between clinical deficit severity and infarct volume on DW-MRI
• D. Infarct involving more than 2/3 MCA

Answer: (C)

In this context, the purpose of DW-MRI is to gauge how much brain tissue has already suffered irreversible damage (the infarct core) versus how much may still be saved. When the clinical deficit is disproportionately large compared to the small DW-MRI infarct lesion, a mismatch exists. That means there is a substantial amount of tissue at risk but not yet irreversibly damaged, which can potentially be saved with rapid reperfusion. This mismatch supports selecting a patient for thrombectomy within six hours because it identifies salvageable tissue that stands to benefit from treatment.

If the infarct on DW-MRI is already large (involving most of a territory like more than two-thirds of the MCA), there is little salvageable tissue, making thrombectomy less beneficial. While a vessel occlusion is important for eligibility, the specific DW-MRI mismatch finding is the imaging feature that justifies intervention in this window. Age alone does not provide imaging-based guidance.