In DW-MRI mismatch criteria for the 6-24 hour window, which core infarct volume qualifies with NIHSS >=10 and age <80?

• A. <21 mL core infarct with NIHSS >=10 and age >=80
• B. <31 core infarct and NIHSS >=10 and age <80
• C. 31-51 mL core infarct and NIHSS >20 and age <80
• D. >100 mL core infarct

Answer: (B)

In the late window, selecting patients for reperfusion hinges on a mismatch between a relatively small infarct core and a significant clinical deficit on DW-MRI. For patients under 80 with NIHSS at least 10, the key imaging threshold is a diffusion-defined core volume of less than 31 mL. This combination—small core, decent clinical deficit, younger age—identifies those who are most likely to benefit from thrombectomy between 6 and 24 hours.

So, a core infarct volume under 31 mL with NIHSS ≥10 and age <80 fits this criterion best. The other scenarios either modify the age threshold (older patients have a stricter core limit), require a larger core with a higher NIHSS, or present an excessively large core that wouldn’t reflect a favorable mismatch.