If you're going to do HBOT there's no reason to get a SPECT scan. You know you're injured and it will just increase your odds of a brain tumor later along with the CT scans. What the SPECT scan shows won't affect your HBOT routine. Just get a home chamber setup from Summit To Sea and you'll spend a hell of a lot less than 16k and you can do as many dives as you want. The DTI sounds like a good idea but won't inform you as to treatment, it will only tell you where the white matter damage is.

For stem cells, Dr. Hughes in Colorado is where I went. I've had positive and negatives come from it. Several people I've talked to feel they've benefited a lot. If you're really that desperate, his protocol is far more comprehensive/aggressive but you'll pay $12k after factoring in travel and other expenses. There's also the Vielight.

HBOT is the place to start though. You will almost certainly get something out of it.

I went to Cognitive FX as well but only benefited modestly from it.

As to the future, SB623 stem cells by San Bio are now being tested on brain injury patients for motor deficits. These cells have allowed paralyzed stroke victims to begin moving their paralyzed sides the next day in some cases. After the cells are approved for motor impairment it is likely they will be tested on other parts of the brain. The cells have a wound healing gene which is active in the brains of newborns which recover much better than adults after brain injury. The recovery we will get from treatments like this will likely far surpass what we can imagine today.

Stem Cells - Reversing Stroke Damage - YouTube