Digital Subtraction Angiography

Conventional angiography, or more specifically digital subtraction angiography (DSA) can be used for both diagnostic and interventional angiography. Its high spatial and temporal resolution have maintained DSA as a very important tool. DSA was actually invented at UW by a group of medical physicists headed by Charles A. Mistretta, PhD, and UW owns the patent to DSA.

In conventional angiography the patient is catheterized, usually via the common femoral artery in the groin. Wires, catheters, clot retrieval devices, stents and anuerysm coils can be passed to the vessel of interest with this access. Iodinated contrast can be injected into a catheter and observed with fluoroscopy, causing the vessel to show up dark relative to the surrounding. DSA is a method of fluoroscopy where an initial mask image is taken prior to administering contrast and saved. After administering contrast, fluoroscopy is continued and the saved pre-contrast mask is subtracted from these newer images obtained after giving contrast. The result is an image with the background subtracted from the image such that only the contrast enhanced vessels are seen.