New Contrast Agent Provides Improved MRI Scans of Tumors

The ability to trace and visualize tumors continues to increase. Detection and imaging techniques have improved much in recent years, among which one of the most exciting techniques is MRI. Patients who are about to undergo MRI scanning are often injected with a contrast agent, which makes it easier to distinguish tumors from surrounding tissues. The quality of the resulting scan depends partly on the ability of the contrast agent to find the tumor and induce contrast.

At Delft University of Technology (TU Delft; The Netherlands), postgraduate researcher Kristina Djanashvili, Ph.D., has developed a new contrast agent with enhanced tumor affinity and contrast induction characteristics, meaning that tumors can be detected sooner and visualized more accurately. The new agent is a compound incorporating a lanthanide chelate and a phenylboronate group substance. The lanthanide chelate ensures a strong, clear MRI signal, while the phenylboronate group substance targets cancerous tissue.

The lanthanide chelate influences the behavior of water molecules, even inside the human body. It is ultimately the behavior of the hydrogen nuclei in the water molecules that makes MRI possible and determines the quality of the image produced. The stronger the influence of the lanthanide chelate on the neighboring hydrogen nuclei (the so-called water exchange) and the more hydrogen nuclei affected, the better the MRI signal obtained.

Dr. Djanashvili has provided her contrast agent with enhanced tumor-seeking properties by including a phenylboronate group substance. Phenylboronate has an affinity with specific sugary molecules that tend to concentrate on the surface of tumor cells. What makes the selected phenylboronate-containing agent valuable is its ability to chemically bond with the surface of a tumor cell.

Finally, Dr. Djanashvili has managed to incorporate the compound into so-called thermosensitive liposomes. A thermosensitive liposome forms a sort of protective ball, which opens (releasing the active compound) only when heated to approximately 42 ^oC. This means that, by localized heating of a specific part of the body, it is possible to control where the compound is released. The positive results obtained from evaluating the new agent on mice open the way for additional research, according to Dr. Djanashvili.

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Delft University of Technology