<unk>  and fluoroscopy In traditional angiography, images are acquired by exposing an area of interest with time-controlled x-rays while injecting a contrast medium into the blood vessels. The image obtained includes the blood vessels, together with all overlying and underlying structures. The images are useful for determining anatomical position and variations, but unhelpful for visualizing blood vessels accurately. In order to remove the distracting structures to see the vessels better, first a mask image is acquired. The mask image is simply an image of the same area before the contrast is administered. The radiological equipment used to capture this is usually an X-ray image intensifier, which then keeps producing images of the same area at a set rate (1 to 7.5 frames per second). Each subsequent image gets the original "mask" image subtracted out. (Mathematically, the incoming image is divided by the mask image) The radiologist controls how much contrast media is injected and for how long. Smaller structures require less contrast to fill the vessel than others. Images produced appear with a very pale grey background, which produces a high contrast to the blood vessels, which appear a very dark grey. Intravenous<unk>  Intravenous<unk>  (IV-DSA) is a form of angiography which was first developed in the late 1970s. IV-DSA is a computer technique that compares an X-ray image of a region of the body before and after radiopaque iodine based dye has been injected intravenously into the body. Tissues and blood vessels on the first image are<unk> ly subtracted from the second image, leaving a clear picture of the artery which can then be studied independently and in isolation from the rest of the body. Some limited studies have indicated that IV-DSA is not suitable for patients with diabetes or kidney failure because the dye load is significantly higher than that used in arteriography. However, IV-DSA has been used successfully to study the vessels of the brain and heart and has helped detect carotid artery obstruction and to map patterns of cerebral blood flow. It also helps detect and diagnose lesions in the carotid arteries, a potential cause of strokes. IV-DSA has also been useful in assessing patients prior to surgery and after coronary artery bypass surgery and some transplant operations.
Digital subtraction angiography
Microangiography
Digital variance angiography
Radionuclide angiography
Rotational angiography
Intravascular imaging
Computed tomography angiography
Magnetic resonance angiography