MR angiography (MRA) is an MRI study of the blood vessels. It utilizes MR technology to detect, diagnose and aid the treatment of heart disorders, stroke and blood vessel diseases. MRA provides detailed images of blood vessels without using any contrast material, although today a special form of contrast usually is given to make the MR images even clearer. The procedure is painless, and the magnetic field is not known to cause tissue damage of any kind.