A diagnostic contrast composition includes a carrier fluid and a non-decaying gas-evolving fluid incorporated in the carrier fluid. The gas-evolving fluid has a vapor pressure sufficient to evolve the gas from a circulatory system within a lung of a patient. The gas-evolving fluid is a composition containing a sufficient quantity of atoms with an atomic number higher than 8 to provide an increased absorption sufficient to increase a Hounsfield Unit measurement in an image in a CT imaging system. The gas-evolving fluid is selected from the group consisting of xenon gas, krypton gas, sulfur hexafluoride, a perfluorocarbon, a brominated perfluorocarbon, and combinations thereof. The carrier fluid is selected from the group consisting of water, saline, saline comprising one or more blood proteins, and saline comprising dissolved lipids.

An implantable tissue marker incorporates a contrast agent sealed within a chamber in a container formed from a solid material. The contrast agent is selected to produce a change, such as an increase, in signal intensity under magnetic resonance imaging (MRI). An additional contrast agent may also be sealed within the chamber to provide visibility under another imaging modality, such as computed tomographic (CT) imaging or ultrasound imaging.

Described herein are compositions composed of a radiopaque agent and a cyanoacrylate monomer. These compositions cure in situ when administered to a subject and, thus, have numerous biomedical applications. The presence of the radiopaque agent allows the practitioner to visualize the compositions during and immediately after administration to the subject. The compositions are non-toxic and shelf-stable, and can be sterilized to prevent microbial growth. The compositions can be pre-mixed prior to sale and distribution, reducing the need for special training in their use.