Which digital fluoroscopic study continuously changes masks to provide information on changes in contrast media content?

The correct choice refers to time interval difference imaging, a technique employed in digital fluoroscopy. This method is notable for its ability to create a sequence of images that illustrate changes over time, making it particularly useful for visualizing alterations in the concentration of contrast media within a given anatomical area.

In time interval difference imaging, a series of images are captured at specific time intervals. By comparing these sequential images, the system can detect even subtle variations in how contrast media enhances different tissues or structures, leading to enhanced visualization of vascular or pathological changes. This dynamic assessment allows practitioners to make more informed diagnostic decisions based on the kinetic behavior of contrast agents.

The other methods—such as masks mode fluoroscopy, synchronized fluoroscopy, and K-edge fluoroscopy—do not primarily focus on this specific dynamic adjustment of contrast media over time. Instead, they relate to different applications or mechanisms of imaging in fluoroscopy and do not provide the continuous, real-time assessment of contrast dynamics that time interval difference imaging offers. This distinction highlights the uniqueness and importance of time interval difference imaging in clinical practice.