General information
Angiography is an imaging technique used in medical diagnostics in which blood vessels and related vascular systems can be made visible. In most cases, except for MRI, a contrast medium is injected into the vascular region to be examined. Using radiological imaging methods, for example X-rays, an image of the corresponding region is recorded.
The contrast medium is distributed with the blood flow in the surrounding vessels and lights up in the X-ray image. This allows the vascular drawing to be accurately assessed with regard to the position and course, as well as the shape and pathological changes in the vessels. Depending on the vessel to be examined, different types of angiography can be used.
These differ in the type of contrast medium and the recording by MRT, CT or ultrasound. The contrast medium is injected through a catheter after puncture of an upstream blood vessel. This puncture can lead to minor complications.
Indications
In most cases, angiography provides precise information about the location and morphology of a blood vessel system. This makes it possible to assess the blood flow in the vessel and the supply of blood to a downstream organ. For many important vascular diseases, both arterial and venous, angiography offers a precise diagnosis possibility.
Venous thromboses and varicose veins can be depicted with venous angiography and their extent can be assessed. In the case of leg vein thromboses, the examination is called phlebography. Here, a blood clot blocks the flow in the vein.
The angiography of varicose veins is called varicography. Here, the superficial leg veins dilate enormously due to a congestion of blood. Diseases of the arterial vascular system include vascular injuries, arteriosclerosis, which is accompanied by vascular constriction, and aneurysms.
An aneurysm is a bulging of the arteries that can occur anywhere and, in the worst case, burst. Angiography with contrast medium allows these vascular diseases to be depicted in several images in such a way that both the morphology and the function of the vessel can be assessed. It also provides precise position information, which is important for planning before vascular surgery. Angiography also provides the opportunity to perform surgery immediately after diagnostic imaging. This can consist of dilating a vessel, placing a stent, treating an aneurysm or removing blood clots.
DSA
DSA stands for “digital subtraction angiography”. It is a variant of angiography in which the procedure remains the same, but the image is digitally processed. The aim is to make disturbing structures outside the vascular system invisible in the radiological image.
This is possible by taking images before and after injection of the contrast medium. The computer digitally subtracts both images from each other so that only the contrast medium and thus the inside of the blood vessels can be seen. By taking several images even while the contrast medium is being injected, a kind of film sequence is created in which the spread of the medium over the vessels can be seen. This, and by masking out disturbing aspects of the image in subtraction angiography, allows the most accurate possible assessment of the form and function of the vessels to be made. Radioactive iodine particles are mainly used as contrast medium in DSA, but newer methods can also work with saline solutions or CO2 as contrast medium.
