Highly Sensitive Detection of MRI Contrast Agents
Scientists have developed a sensor capable of detecting even the smallest amounts of gadolinium.
magnetic resonance imaging, or MRI for short, provides detailed images of the inside of the body. It is an indispensable procedure for diagnosing and planning treatment for many types of cancer, and it does not expose the body to radiation because it uses magnetic fields and low-energy radio waves. Pathological changes, such as tumors, can be clearly distinguished from healthy tissue in MRI images.
The element gadolinium provides the necessary contrast for MRI images; it is securely enclosed in a so-called chelate molecule—like a molecular cage—within the contrast agents. Due to its unique magnetic properties, gadolinium interacts with water molecules in the body inside the MRI scanner. Certain water-rich tissues thus appear brighter in the images, which creates contrast in the imaging.
Gadolinium-based contrast agents are used in just under half of all MRI examinations. After the examination, these are excreted via the kidneys in urine and enter wastewater. There, gadolinium remains bound within its chelate cage over the long term. “Nevertheless, we see an urgent need to lay the groundwork for new and sensitive analytical methods that will allow us to track gadolinium from contrast agents, as well as from industrial processes, in the environment,” explains Leif Schröder of the DKFZ, who led the study.
Measuring Gadolinium Down to the Micromolar Range
The scientists combined two effects. First, they used hyperpolarized xenon, a strongly magnetized noble gas enclosed by a different type of cage, which produces signals in MRI. Here, the nuclear spin of the xenon acts as a quantum sensor and produces two distinct signals: one for the xenon bound within the cage molecules and one for the free xenon in the solution. Second, gadolinium displaces the xenon from its cage, causing the corresponding xenon signal to weaken and eventually disappear entirely.
“Based on the reduction in the xenon signal, we were able to determine the concentration of gadolinium outside the cage,” says Hannah Gerbeth, first author of the study. The DKFZ research team found that gadolinium measurements in the micromolar range are possible. Under the experimental conditions, this makes the cage molecule a highly sensitive sensor for gadolinium. “This discovery shows that the unique properties of the interaction between gadolinium, xenon, and the cage allow for more sensitive detection than was possible in previous MRI studies,” says Leif Schröder.
The method, which distinguishes free gadolinium from chelated forms, could help improve clinical applications and the detection of gadolinium-containing substances in the environment. In the future, the scientists plan to test the sensor’s suitability for determining gadolinium in other concentration ranges as well. They also intend to investigate whether other ions are selectively bound by the cage and could thus interfere with the gadolinium sensor.
Note: This article has been translated using a computer system without human intervention. LUMITOS offers these automatic translations to present a wider range of current news. Since this article has been translated with automatic translation, it is possible that it contains errors in vocabulary, syntax or grammar. The original article in German can be found here.
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