Everything in your body is nurtured by your blood. Without having nutrient-rich blood traveling throughout your body, vital organs would not receive the material they need to function. Your brain needs good blood flow, your limbs, your skin, and organs too. Following this logic it makes sense that without good blood flow to your hair, it will not grow well, and will even start to die. If you rob your hair of the nutrients and other materials that it needs to thrive, then it will wither.
Decreased Blood Flow Leads to Hair Loss
Many things can lead to premature hair loss in a person. Hair loss can be brought on by a poor diet, inflammation of the scalp, imbalances in internal chemistry, and by decreased blood flow. It is also true that a bald head will have less blood flow too. Without hair actively requiring nourishment to grow, your body will send less blood to your scalp and it will remain a poor area to grow hair.
Increasing Blood Flow
The solution to your problems is not to go through some ridiculously expensive and invasive surgery to artificially make your blood pump better to your scalp. What you want to do is to provide a healthy environment for your body to grow in. To do this give it a good diet that contains all of the minerals, nutrients, and calories that it needs to produce healthy hair. If you give your body what it requires to function then it will correct low blood flow on its own and your scalp will begin to see decreased hair loss, and even hair regrowth over time.
Unfortunately testing for blood flow is not going to be very effective. If you are already balding or bald you are going to find that you have less blood flow to your scalp. This may or may not be because of a lack of nutrients. Your body naturally sends less blood to the scalp when it is not growing hair. It is a leap of faith of your part to improve your diet and lifestyle in order to promote healthier levels of blood flow in your body. There is a good chance that this will help your hair repair itself, or even begin to grow back in.