Digital+Subtraction+Angiography

= = =Digital Subtraction Angiography=
 * [|Digital Subtraction Angiography]** (also known as DSA) is a technique that creates a visual image of blood vessels in a soft tissue environment. Images are taken before and after a [|contrast medium]is placed in the blood stream. The computer subtracts the before and after image to eliminate organs and body parts that block a clear view of vessels.

=History and Future=
 * DSA**, also known as fluoroscopy, dates back to late 1900's. Today it is becoming a less common form of treatment and is being replaced with [|CTA] (Computed Tomography Angiography), which is a similar technique using 3D images of blood vessels and is less intrusive towards the patient than the previous DSA.

= = = = = = = = = = = = = = =Treatments= It also helps detect cerebral anuerysms along with [|AVM]s. All of these disorders effect the bloodstream, from the heart to the brain.
 * Digital Subtraction Angiography** can be used to help identify many disorders and diseases involving blood vessels. Some of the most common uses of DSA are on [|pulmonary embolism] and [|carotid atery stenosis].

= = = = = = = = = = = = = = = = = = =Process= DSA images are obtained by exposing a particular area of the body to an [|x-ray]. During the x-ray a contrast medium is placed into the bloodstream to distinguish them from other organs. However, when these images are taken other organs and body parts obscure vessels, limiting doctors to what is visible. In order to eliminate this flaw, an image is taken before and after the medium is injected. Both images are put onto a computer and 'subtracted' from each other, revealing only the blood vessels needed. The final images appear pale and grey in the background and the blood vessels are black.