What type of imaging can be enhanced using the administration of contrast agents?

The use of contrast agents plays a crucial role in enhancing the visibility of structures and abnormalities in various imaging modalities. In the context of imaging, X-rays and CT scans greatly benefit from contrast agents, which are substances introduced into the body to improve the contrast of the images produced.

For X-ray imaging, contrast agents, such as barium or iodine-based compounds, are often used to delineate the gastrointestinal tract or blood vessels. This allows for clearer visualization of the organs and can help in identifying conditions such as blockages or tumors.

Similarly, in CT scans, contrast agents enhance the differentiation between tissues and vascular structures. They enhance the contrast between normal and abnormal tissues, making it easier for healthcare providers to diagnose various conditions, including tumors, infections, or other pathological changes.

In contrast, bone density scanning primarily assesses bone mineral density and does not typically require the use of contrast agents for its purpose. Electrocardiograms and pulse oximetry measure different physiological parameters (heart activity and oxygen saturation, respectively) and do not involve imaging techniques where contrast agents would be applicable.

Thus, X-ray and CT scans are the correct choice because they utilize contrast agents to significantly enhance image quality and diagnostic capability.