MRS (Magnetic Resonance Spectroscopy) would probably be more beneficial. It's likely expensive too, and not covered by most insurance companies. From my reading, I understand it to measure or gather information about biochemicals such as neurotransmitters. It has mostly been used by researchers but may become more common for proper diagnosing in some cases.
I came across this when I was researching glutamate. So much information to learn about this amino acid and it's relationship to mental disorders. It's the most abundant amino acid and it's levels being too high are common in people with bipolar or schizophrenia. The med I take, Lamictal, is an antagonist to it. MRS should be able to show the glutamate levels in comparison to other neurotransmitters. The MRI would be able to show physical damage to the brain structure over time. In some autopsy MRI studies, there was evidence that the hippocampus was damaged in a brain that had glutamate levels in excess. This is supposed to be what happens when the brain is damaged after a stroke or traumatic brain injury. Glutamate dumping into the brain....bad! It makes sense that lowering it would help those of us with too much of this exciting transmitter. Too low causes many issues too, I'm sure.
There is interesting research showing that the amino acid, L-cystine, is beneficial to reduce glutamate, and increase glutathione, which is a super antioxidant for fighting free radicals in the body. Perhaps I should experiment and get off the lamictal...and change to OTC L-cystine ffrom the health food store...
https://www.ncbi.nlm.nih.gov/pubmed/10736372https://www.sciencedirect.com/topics/neuroscience/glutamic-acidhttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC3482580/