Final answer:
In MRI, oral contrast agents help to make the bowel more visible by providing greater contrast, with gadolinium-based agents commonly used to modify the magnetic properties of water in tissues for better image clarity.
Step-by-step explanation:
The oral contrast agent used in MRI makes the bowel appear more visible and provides a greater contrast against other tissues. Different contrast agents are utilized for various imaging purposes. For instance, barium sulfate is a common oral contrast agent used in X-ray imaging, and it works by coating the intestinal tract to offer detailed views of the gastrointestinal tract, enhancing visualization of conditions such as acid reflux disease, Crohn's disease, and ulcers. However, in MRI, contrast agents like gadolinium-based complexes are used, which affect the magnetic properties of water in tissue cells, thereby improving image contrast and detail. These MRI contrast agents are injected to help differentiate between different types of soft tissues and to provide clearer images of internal structures.