Subtraktionangiographie

Subtraktionsangiographie is a medical imaging technique used to visualize blood vessels. It involves acquiring two X-ray images of the same area, one before and one after the injection of a contrast agent into the bloodstream. The first image, known as the mask image, shows the underlying bone and tissue structures without the contrast. The second image, the contrast image, shows the vessels filled with the contrast agent superimposed on the same bone and tissue structures.

The core principle of subtraction angiography is to digitally subtract the mask image from the contrast image. This process removes the signals from the bone and soft tissues, leaving only the contrast-filled blood vessels clearly visible. This enhancement significantly improves the visualization of even small or narrow vessels, which might otherwise be obscured by surrounding anatomy.

The technique is particularly useful in diagnosing and assessing conditions affecting arteries and veins, such as aneurysms, arteriovenous malformations, stenoses (narrowing), and occlusions (blockages). It plays a crucial role in interventional radiology, guiding procedures like angioplasty, stent placement, and embolization. While effective, subtraction angiography involves radiation exposure and the risks associated with contrast media, such as allergic reactions. Despite the advent of newer imaging modalities like CT angiography and MR angiography, subtraction angiography remains a valuable tool in specific clinical scenarios.