I feel like too much weight is placed on imaging in the case of MTBI and PCS after the initial acute injury (where bleeding would be a major concern). Doing MRI's later into the PCS recovery is like scanning someone who has diabetes, seeing their pancreas, and assuming they're fine. Physically things can look normal but physiologically the function is altered.

Personally I have had a clean MRI as well as EEG and all sorts of other ENT tests. The only thing that validated what I was experiencing cognitively was a neuropsych assessment. I think that a neuropsych assessment is a better use of resources as it helps to pin point and identify your specific strengths and weaknesses and can serve as a guide for rehab as well as validating the problems you are experiencing (in a way that an unremarkable MRI scan can not).

Also, remember that you are a health care consumer. It's particularly hard when you're suffering with something like a brain injury but you need to find health care professionals that you can work with. That might mean trying out a few doctors/therapists/etc but in the end you'll be better off health wise.

To add my experience to the list:
I would say that it is worth getting a comprehensive set of tests, if they are available, but probably not worth redoing an MRI unless there is a really good reason such as it not being clear due to the fact that you were moving the first time.

If the MRI was done well the first time then surely repeating it will show up exactly the same things. It would be different if they were thinking about doing some sort of functional MRI, which might show up something more.

I think that all brain injuries are different, although there can be similarities.
In my own case, my MRI showen no abnormal structure in the brain. However, I specifically asked for a cervical MRI as well, because my neck had been injured, and that did show up a prolapsed disc. So, I would say that in my case it was worth doing. EEG and QEEG also showed up abnormalities, which were worth knowing about. Those test would be worth repeating periodically as they could show differences, hopefully improvements. Likewise, neuropsychological testing and balance testing can show up things. However, doctors are sometimes reluctant to test in case they find abnormalities, because they don't know how to treat them.

Personally I would like to know what was wrong even if that did not affect my treatment in any way, but that is a personal choice.

CS