Actually no, it won't.
Actually no, it won't.
It's possible to determine that significant damage occurred prior to dehydration, but it's not possible to tell how much functionality remained. Further, no type of mere structural examination (whether CT scan, MRI, or autopsy) can reliably ascertain a patient's clinical condition. There are people who can walk and talk whose CT scans would suggest that they couldn't possibly be alive (and yet they are).
Brains are very weird and interesting things. Although there generally seem to be limits to an adult brain's ability to route around problems, for many perceived limits there are cases that exceed them.