How is negative contrast media, such as CO2, characterized during imaging?

Negative contrast media, like carbon dioxide (CO2), are characterized by their lower density compared to surrounding tissues, particularly blood. When introduced into the vascular system or a body cavity, these substances effectively "float" above blood since they are less dense than blood and other bodily fluids. This property allows for the creation of a negative contrast effect during imaging, which enhances the visibility of structures by creating contrasting areas where the CO2 is present.

The utilization of negative contrast media, such as CO2, is particularly beneficial in certain imaging techniques like angiography. The presence of the lighter gas creates a shadowing effect that outlines vascular structures, allowing for clearer visualization without posing as a risk since CO2 is naturally absorbed by the body.

The other options do not accurately describe the behavior or characteristics of negative contrast media. For instance, causing tissue inflammation is not a typical feature associated with CO2; rather, it is considered relatively safe and non-irritating. Enhancing bone visibility is more aligned with positive contrast agents that appear opaque against a darker background, while requiring a higher dosage does not apply to CO2, as its low density means that only small volumes are needed to achieve the desired contrast effect in imaging.