DKFZ builds xenon-based sensor detecting gadolinium from MRI contrast agents at micromolar levels

Researchers at the German Cancer Research Center (DKFZ) have developed a sensor that detects gadolinium in very small amounts, lomazoma.com reports. Gadolinium is a component of MRI contrast agents and can reach the environment through patients' urine. The study was led by Leif Schröder; Hannah Gerbeth is the first author. lomazoma.comlomazoma.comlomazoma.comOpen source ↗

Under the experimental conditions, the team found that gadolinium can be determined in the micromolar range.

Why gadolinium is tracked

In contrast agents, gadolinium is enclosed in a chelate, a molecular cage. Because of its magnetic properties, it interacts with water molecules in the body, so some water-rich tissues appear brighter in the image. Gadolinium-based agents are used in almost half of all MRI examinations.

After the examination they are excreted by the kidneys in urine and enter wastewater, where gadolinium stays bound in its chelate cage. Schröder said there is still an urgent need for sensitive analytical methods that can trace gadolinium from contrast agents, as well as from industrial processes, in the environment. lomazoma.comlomazoma.comlomazoma.comOpen source ↗

How the xenon sensor works

The researchers combined two effects. They used hyperpolarized xenon, a strongly magnetized noble gas enclosed in a different cage molecule, which produces signals in MRI. The xenon nuclear spin serves as a quantum sensor and gives two distinct signals: one for xenon bound in the cage and one for free xenon in solution.

Gadolinium displaces xenon from its cage, so the bound-xenon signal becomes smaller and eventually disappears. From this reduction the team determined the concentration of gadolinium outside the chelate cage.

According to Schröder, the interaction of gadolinium, xenon and the cage allows more sensitive detection than earlier MRI-based research. The authors say that distinguishing free from chelated gadolinium could help improve clinical use and the detection of gadolinium-containing substances in the environment. lomazoma.comlomazoma.comlomazoma.comOpen source ↗

Next steps

The team plans to test the sensor in other concentration ranges. They also want to examine whether the cage selectively binds other ions that could interfere with the gadolinium measurement.