What is your preferred imaging modality for determining infarct core when evaluating acute stroke cases?

MRI is the best imaging modality for determining core infarct, but non-contrast head CT and CT perfusion imaging are more practical and faster, so they are used by a vast majority of centers. I use CT and CTP because they are much faster to obtain at my institutions.

I agree with prior responses. In most cases, a combination of CT & CTA with ASPECTS scoring & collateral assessment is sufficient to determine infarct core burden. I don't routinely rely on MRI for EVT or thrombolysis assessment due to logistical and/or time constraints. CTP can be hit or miss, but may offer added value in MeVO cases when core/penumbra distinction is unclear.

Here is my simplified algorithm I use in most cases for deciding on both TNK and thrombectomy.

First line is CT and CTA head and neck, looking at ASPECTS and collateral flow. If both favorable and within 4.5h for TNK and 6h for thrombectomy, proceed with treatment. If presenting beyond 6h, I add CTP. Although I suspect future studies will find that ASPECTS and collateral score alone are probably adequate in most cases, and we will no longer have to get CTP on everyone beyond 6h.

If collaterals a...

I like Aspects also, although at times I use MRI.

I agree with the above answers. ASPECTs on non-contrast CT and CTA collateral assessment for anterior circulation. CTP may add some value for anterior circulation distal occlusion, but more so for the penumbra, as sometimes, if there is perfusion in the infarcted tissue, it may not meet the core threshold on CTP. For posterior circulation (when and where needed), MRI in my experience to determine the core has been the best to look at the DWI FLAIR mismatch.