MRI's are not usually used for this purpose. CT's are, and they are enhanced with isotopes to show the vascular array.
You don't need MRI tests unless you are looking for muscle and tendon problems.
Besides, she had a MRI early on to do just that apparently, because the Dr. said he saw one...
I think you may be right on that. There is something new out on this and I don't have it on the tip of my fingers.