The imaging technique called provides information about what part of the brain does blood go by injecting a radioactive dye

There are two tests that are used for this. The less invasive test would be CT Scan with contrast. The minimum invasive approach isca test called Cerebral angiography where an iodine contast is injected intravenously and an imaging catheter is inserted through the groin all the way up to the brain to see how blood is circulating

It is very important to stay hydrated. your body needs it for may things for cells, tissues, your organs and etc. water also with your temperature that way you don’t get a headache etc. i bet if you look it up there will be a lot of things you can learn.