Digital subtraction angiography ( DSA ) is a fluoroscopy technique used in interventional radiology to clearly visualize blood vessels in a dense soft tissue environment or bone. Images are produced using contrast media by subtracting "pre-contrast images" or masks from the next image, after which contrast media has been introduced into the structure. Therefore the term "digital reduction angiography". The reduction of angiography was first described in 1935 and in English sources in 1962 as a manual technique. Digital technology made DSA practical from the 1970s.
Video Digital subtraction angiography
Prosedur
DSA dan fluoroscopy
In traditional angiography, images are obtained by exposing an interesting area with time-controlled x-rays while injecting contrast media into the blood vessels. The images obtained include blood vessels and all of its upper and underlying structures. These images are useful for determining anatomical positions and variations, but they do not help to accurately visualize blood vessels.
To eliminate this annoying structure to look at the blood vessels better, first the mask image is obtained. The mask image is just a picture of the same area before the contrast is given. The radiology equipment used to capture this is usually an X-ray image intensifier, which then continues to produce images from the same area at the specified level (1 to 7.5 frames per second). Each subsequent image gets the original "mask" image subtracted. (Mathematically, the incoming image is divided by the mask image.) The radiologist controls how much contrast medium is injected and for how long. Smaller structures require less contrast to fill vessels than others. The resulting image appears with a very pale gray background, which results in high contrast on the blood vessels, which look very dark gray.
All images are produced in real time by a computer or image processor, while contrast is injected into the blood vessels.
Angiography of intravenous digital reduction
Intravenous digital subtraction angiography (IV-DSA) is the first angiography form developed in the late 1970s.
IV-DSA is a computer technique that compares X-ray images of a body region before and after dye-based iodine radioxy has been injected intravenously into the body. The tissues and blood vessels in the first image are digitally subtracted from the second image, leaving a clear picture of the artery which can then be studied separately and separated from the rest of the body.
Several limited studies have shown that IV-DSA is not suitable for patients with diabetes or renal insufficiency because the dye load is significantly higher than that used in arteriography. However, IV-DSA has been successfully used to study brain and heart vessels and has helped detect carotid artery obstruction and to map out patterns of cerebral blood flow. It also helps detect and diagnose lesions in the carotid artery, the potential cause of stroke.
IV-DSA is also useful in assessing patients before surgery and after coronary artery bypass surgery and some transplant surgeries.
Maps Digital subtraction angiography
Apps
DSA is primarily used for vascular images. It is useful in diagnosis and treatment:
- Occlusion of arteries and veins, including carotid artery stenosis, pulmonary embolism, and acute limb ischemia.
- Arterial stenosis, which is particularly useful for potential kidney donors in detecting renal artery stenosis. DSA is a gold standard investigation for renal artery stenosis.
- Cerebral aneurysms and arteriovenous malformations (AVM).
The future
DSA is done less and less regularly in the imaging department. It is replaced by computed tomography angiography (CTA), which can produce 3D images through less invasive and stressful tests for patients, and magnetic resonance angiography (MRA), which avoids X-rays and nephrotoxic contrast agents.
See also
- Angiography
- Computed tomography angiography (CTA)
- Contrast media
- Peripheral artery disease
- X-ray image intensifier
References
Further reading
- Anagnostakos, Nicholas Peter; Tortora, Gerard J. (1990). Principles of Anatomy and Physiology . San Francisco: Harper & amp; Line. ISBN: 0-06-046694-4.
Source of the article : Wikipedia
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