Final answer:
A catheter is used in a nonselective angiography to inject large amounts of contrast solution, as it can be navigated through the vascular system and deliver the contrast effectively. Other options like syringes or needles are not suitable for high-volume injections, and a stent is not for injection but used post-angioplasty.
Step-by-step explanation:
During a nonselective angiography, a catheter is typically used to rapidly inject large amounts of contrast solution into the bloodstream. This process helps to visualize blood vessels within the body, allowing for the diagnosis and treatment of conditions such as occlusions or blockages. A catheter is ideal for this purpose because it can be precisely navigated through the vascular system to the target area and can deliver contrast effectively. In procedures like angioplasty, a specialized catheter with an expandable balloon tip is inserted and directed to the site of the occlusion, where the balloon is inflated to compress plaque and open the vessel. Additionally, a stent may be inserted to maintain vessel patency.
While a needle may be used initially to gain access to a vessel, and a syringe could be used for small injections, neither is suitable for the high-volume injection required in angiography. A stent is not used for injection, but rather to reinforce vessel walls post-angioplasty.