Which imaging technique is used to visualize blood vessels?

Angiography is a specialized imaging technique used primarily to visualize blood vessels in order to assess their condition and any abnormalities. This procedure involves the introduction of a contrast agent into the blood vessels, which enhances the visibility of these structures during imaging. Angiography is particularly valuable for diagnosing conditions such as blockages, aneurysms, and vascular malformations, as it allows for detailed visualization of the vascular anatomy.

Other options, while related to medical procedures, do not pertain to imaging blood vessels. Plasty is a surgical repair or reconstruction of a body part; ostomy refers to a surgical opening created to remove waste from the body; and anticoagulants are medications used to prevent blood clotting but do not relate to imaging. Therefore, angiography stands out as the correct answer for visualizing blood vessels.