In this interview with MEDICA.de, Dr. Leif Schröder from the Leibniz Institute for Molecular Pharmacology (FMP) explains how xenon magnetic resonance imaging is not just applicable in medicine, but also in other areas.
Dr. Schröder, how does xenon magnetic resonance imaging work?
Leif Schröder: Xenon magnetic resonance imaging is a particular advancement of traditional magnetic resonance tomography. It uses so-called hyperpolarized xenon, a harmless noble gas combined with a special contrast agent to create a stronger signal. To do this, the xenon atoms are modified in their magnetic properties in a laser machine to where it becomes possible to create a very strong signal with relatively few atoms.
During the next step, the xenon atoms need to be connected to specific cell structures. We managed to accomplish this step with a type of modular system, in whose development the task force of Christian Freund at the Free University of Berlin was instrumental.
Here the cryptophane molecules, which are a component of the administered contrast agent, bind the xenon atoms. The xenon is temporarily being locked up in this cryptophane cage as it were. It represents the link between a molecular target – a receptor on the cell surface for example – and the xenon, which is ultimately being detected. The cage in turn can be easily used as a probe in the human body. The cryptophane ties to disease-specific markers on the cell surface. The temporarily trapped xenon in the cage then resonates with the radio waves. We were also able to create bi-color signals by adding an alternative to the cages. The xenon subsequently responds to radio waves in a different frequency, so that some cells are depicted in green and others in red color.
Xenon magnetic resonance imaging can therefore be used for very specific diagnostics, which is not possible with other MRI contrast agents, since it can be specifically developed for different markers.
What does an examination look like using this process?
Schröder: At first, the contrast agent that specifically binds to the marker is being administered. After a while, it accumulates in the abnormal tissue. Compared to the conventional method, you then need to additionally administer the xenon. This can be done in two different ways. One way is to administer the xenon by inhalation. The patients would then need to inhale a gas mixture that partially contains xenon. Alternatively, you can dissolve the xenon ahead of time in certain substances such as blood plasma that is being injected, so it is immediately available in the bloodstream.