wakey,

I have had an MRA. It is basically a double MRI. During the MRI, they set up the sensors to only recognize the non-blood tissues in the brain. They then subtract the MRI image without the blood showing from the complete MRI image. The result is the blood vasculature. The images are quite interesting. Mine shows a 'slight out pouching' in the top of my brain stem that would be considered an aneurism if it was larger. The small size is not a concern. Lucky because brain stem aneurisms are all but impossible to treat.

There are ultra-sound images they can do to look at the vasculature in the brain. It is called Dopler Ultra Sound.

Have you had a tilt table test? This evaluate how your body reacts to changes in postural position. Some times, a therapist will prescribe exercises where you slowly change positions to stimulate the vaso-constrictors to operate better. Injury to cerebral vaso-constriction function is common with head injuries.