Karthik Mallina, unfortunately fMRI can't really 'detect' anything - first an fMRI specialist has to annotate and interpret the signal/noise output in a way that provides a satisfactory "functional" narrative.

Identifying any meaningful difference in brain "ischemic tolerance" would require a substantial longitudinal study with set, non-arbitrary predictions, and verifiable tracking of ischemic outcomes. I do not foresee such a study happening, nor would I expect fMRI to provide any clinical insight or practical predictions, were it included.

This is my very cynical take. Others may see things differently.

You can try for PET scan. Otherwise with some advanced fMRI methods this sort of functional changes can be seen

Upto now no gold standard or best non invasive method to detect neuroprotection in humans are not available, but fMRI will help somehave.