Magnetic Resonance Angiogram (MRA)
MRA:The magnetic resonance angiogram, or MRA, is a noninvasive test that has demonstrated usefulness in defining the anatomy of blood vessels of certain size in the head and neck. MRA serves as a complement to traditional MRI scanning in evaluation of the brain and neck. Conventional angiograms, whereby contrast material is injected through a catheter into the blood vessels of the head and neck, are the gold standard (most accurate) for determining the anatomy of these vessels. The advantages of MRA is that it is faster and easier (it does not involve the catheters, contrast material, and risks of angiograms). Another advantage is that MRA also gives an image of the tissue of the brain. MRA is a general term that refers to various imaging techniques that are used to visualize the blood vessels by using magnetic resonance (MR) signal changes that are affected by changes in the flow of blood caused by changes in the shape of the blood vessels. MRA can be used to detect small ballooning of the blood vessels (aneurysms) as small as 4 millimeters in diameter. Smaller aneurysms can require an angiogram for detection. The sensitivity of MRA in detecting aneurysms can be affected by bleeding within the brain and the location of the aneurysms within the brain. MRA can also detect abnormal design (malformations), and atherosclerosis of blood vessels within the brain. Atherosclerosis of the carotid arteries of the neck can be visualized with MRA. MRA does not have significant application for the detection or definition of cancer of the brain.