Radiology Practice Test

Which type of contrast medium is commonly used for CT scans?

1. Barium sulfate

2. Water-soluble iodine-based agents

3. Gadolinium

4. Carbon dioxide

The correct answer is: Water-soluble iodine-based agents

Water-soluble iodine-based agents are the most commonly used contrast mediums for CT scans due to their excellent ability to enhance the contrast of various tissues and structures within the body. These agents have a high atomic number, which allows them to absorb X-rays more effectively than surrounding tissues, resulting in clearer images. This property is particularly useful in identifying and delineating vascular structures, tumors, and inflammatory processes. When administered intravenously, these iodine-based contrasts can circulate rapidly through the bloodstream and provide detailed imaging of organs and vascular systems. Their water-soluble nature allows for quick excretion through the kidneys, minimizing the risk of retention and potential toxicity, making them safer options for many patients. Other contrast mediums like barium sulfate are primarily used for gastrointestinal imaging rather than for CT scans of other body areas. While gadolinium is a great contrast agent for MRI, it is not typically used in CT imaging. Carbon dioxide can occasionally be used as a contrast agent for specific indications, mainly in vascular imaging, but it is not standard practice for routine CTs.