Veins are the tubes in the cardiovascular system that guide and carry blood back to the heart. Veins begin in the capillaries and terminate in the atria. Small veins begin in the capillaries and gradually merge into medium and large veins during the return process to the heart and finally into the atria. The venous valves in the venous vessels are damaged and do not close properly, resulting in a continuous flow of blood from the veins. What are the examination methods? 1.Angiography Angiography refers to the introduction of contrast agent into the target vessel to make the target vessel visible for diagnostic purposes. Nowadays, angiography usually refers to digital subtraction angiography, which is a technique that uses computers to process digital image information to eliminate bone and soft tissue images and make blood vessels clearly displayed. Magnetic resonance angiography Magnetic resonance angiography (MRA) is an examination method that uses electromagnetic waves to produce images of two-dimensional or three-dimensional structures of the body. It is also sometimes called “magnetic resonance imaging (MRI)”. It is a kind of tomography, which uses the magnetic resonance phenomenon to obtain electromagnetic signals from the body and reconstruct information about the body. 3, computerized tomography CT examination CT is a full-featured disease detection instrument, it is the abbreviation of electronic computer X-ray tomography technology. CT examination is based on different tissues of the human body on the absorption and transmission rate of X-rays, the application of extremely sensitive instruments to measure the human body, and then the measurement of the data obtained into the electronic computer, electronic computer processing data, you can After the data is processed by the electronic computer, a cross-sectional or three-dimensional image of the examined part of the body can be taken, and small lesions in any part of the body can be detected.