Magnetic Resonance Venography (MRV): MRV is a technique that uses MRI (Magnetic Resonance Imaging) technology to generate images of the intra and extra cranial venous anatomy. MRIs use magnetic fields and radio waves to produce detailed images of body tissues. MRV can quickly produce detailed time-resolved 3D MR images of the entire head, neck, and aortic arch areas by collecting the data before and after injection of contrast agents. These images can reveal many forms of stenosis and venous abnormalities, including agenesis, hypoplasia, atresia, twisting, and presence of collateral veins clusters and shunts. Visually, MRV can create more detailed 3D images of the venous system than other commonly available technologies.