Which radiologic procedure involves injecting a contrast agent into the bloodstream?

Angiography is a radiologic procedure specifically designed to visualize the inside of blood vessels and organs through the injection of a contrast agent into the bloodstream. This procedure is particularly useful for viewing the vascular system, allowing for the assessment of conditions such as blockages, aneurysms, or other abnormalities in blood vessels.

By injecting a contrast agent, the contrast media enhances the images captured during the procedure, making it easier to differentiate between normal and pathological structures. The use of a contrast agent is crucial in angiography as it provides a means to highlight the areas of interest, improving the diagnostic capabilities significantly.

In contrast, other procedures listed do not primarily focus on injecting contrast agents into the bloodstream for their standard imaging processes. For example, CT scans and MRIs may also use contrast agents, but they do not specifically target the vascular system like angiography does. X-rays do not typically involve any injected contrast; instead, they rely on the body’s natural density differences to create images. Thus, angiography stands out as the procedure that is uniquely defined by its use of injected contrast into the vascular system.