Atomic sensors reveal hidden dynamics of molecular polarization

A small cell containing rubidium metal. The central magnetic field sensing component within an atomic magnetometer. Credit: ICFO
Magnetic resonance imaging (MRI) has long been a cornerstone of modern medicine and provides highly detailed images of internal organs and tissues. MRI machines are large tube-shaped magnets commonly found in hospitals that use powerful magnets to map the density of water and fat molecules in the body.
In addition to these molecules, other substances such as metabolites can also be mapped, but their concentrations are often too low to produce clear images. To overcome this limitation, a technique known as hyperpolarization is used to enhance the magnetic resonance signal of these materials, making them more visible during MRI scans.
Hyperpolarization involves preparing material outside the body with near maximum magnetization, which is key to creating MRI images. This process boosts the signal thousands of times compared to its natural state. Once hyperpolarized, the substance is injected into the patient and transported to the target organ or tissue. However, before this happens, it is important to ensure that the material is properly hyperpolarized through a rigorous quality control process.
Current quality control techniques face two significant challenges. First, these methods often reduce the magnetization of the sample during the reading process, thereby reducing their ability to enhance the MRI scan. Second, the time required for measurements is long, during which time the magnetization of the material naturally decays, which limits the opportunity for continuous measurements. As a result, critical data that can help maximize the efficiency of hyperpolarization is missing.
Additionally, if the sample becomes hyperpolarized, there is a risk that it will lose its magnetization during transport to the MRI machine. Traditional quality control methods are time-consuming and may not be able to detect this loss of time.
This time, IBEC researchers Dr. James Iles (currently at the Jülich Forschung Center in Germany) and Dr. Irene Marco Rius, ICFO researchers Professor Morgan W. Mitchell of ICREA and Michael – Collaborative research with Dr. CD Taylor demonstrates how atomic sensor technology can overcome limitations. Conventional sampling methods can be used when measuring the magnetization of hyperpolarized materials. This breakthrough was recently reported in the Proceedings of the National Academy of Sciences.
Specifically, the research team used an optically pumped atomic magnetometer (OPM). The operating principle of this OPM is fundamentally different from conventional sensors and allows real-time detection of magnetic fields generated by hyperpolarized molecules. The nature of OPM allowed these researchers to perform continuous, high-resolution, nondestructive observations throughout the experiment, including the hyperpolarization process itself.
According to the authors, if the field of hyperpolarization sensing were cinema, traditional techniques would resemble a series of still photographs, leaving the viewer to guess the plot between the still photographs. .
“Instead, our technology is more like video, allowing us to see the entire story frame by frame. Essentially, we can observe it continuously without any resolution limitations, so we don’t miss any details.” ICFO’s Dr. Michael Taylor explains. Researcher and co-author of the paper.
Elucidating the behavior of compounds during magnetization
The research team tested OPM by monitoring the hyperpolarization of clinically relevant molecules. The unprecedented resolution and real-time tracking of atomic sensors allowed us to observe how the polarization of a metabolite compound ((1-13C)-fumarate) changes in the presence of a magnetic field.
Atomic sensors have revealed previously unnoticed “hidden spin dynamics” and provided new avenues to optimize hyperpolarization from the beginning of the process.


Infographic atomic sensor. Credit: ICFO
“Previous methods masked subtle oscillations in the magnetization profile that were previously undetected,” said Taylor. “Without OPM, we would have achieved suboptimal final polarization without realizing it.”
Beyond simple observation, this method can be used to control the polarization process in real time and stop it at the most convenient point, for example when maximum polarization is reached.
The study revealed other unexpected behavior when the team applied a magnetic field to repeatedly magnetize and demagnetize the hyperpolarized fumarate molecules. They expected the magnetization to increase to a maximum and then return to zero many times, each time transitioning smoothly from one state to another. Contrary to these simple expectations, this molecule exhibited complex dynamics due to specific magnetization-demagnetization periods and hidden resonances in the magnetic field.
“This understanding helps us detect when undesired behavior occurs and adjust parameters (such as cycle duration or magnetic field strength) to prevent it,” Tayler explains.
This research represents an advance in hyperpolarized MRI technology, thanks in large part to the collaborative efforts of IBEC’s Molecular Imaging for Precision Medicine Group and ICFO’s Atomic Quantum Optics Group. IBEC’s expertise in hyperpolarization techniques and ICFO’s expertise in OPM sensing technology were critical to achieving the results.
“This is a beautiful example of the new science that can be achieved when researchers from different fields work together, and the proximity of IBEC and ICFO meant that we were able to work closely together to achieve something truly novel. ” admits IBEC’s Dr. James Isles. Researcher and first author of the paper.
Reflecting on the team’s success, Dr. Taylor said, “The OPM measurements worked brilliantly from the start. The exquisite sensitivity of the sensor exceeded our expectations, as if it had been made for this purpose. The ease of use and wealth of new information make it a powerful tool for hyperpolarization monitoring.”
Benefits for MRI and other future applications
The immediate application of this research is the integration of portable atomic sensors into MRI clinical sample quality control, which is currently being carried out by the ICFO team in the Spanish Ministry project “SEE-13-MRI”. In this way, the molecules can be brought to the highest possible polarization level during hyperpolarization and the polarization level can be reliably authenticated before the substance is injected into the patient.
This development has the potential to significantly reduce the cost and logistical challenges of metabolic MRI. This would expand its reach from the few specialized research centers currently used to include many hospitals around the world.
But the potential of atomic sensors goes far beyond medical imaging. The same nondestructive real-time tracking system using optically pumped magnetometers (OPMs) can also be applied to monitor macromolecules in chemical processes, study high-energy physical targets, and even optimize spin-based algorithms in quantum computing. Masu.
Dr. Taylor said, “The method we have developed opens new avenues not only for improving MRI, but also for a variety of fields that rely on accurate magnetic sensing, and we are excited about its further development.” ”.
Further information: James Eils et al, Live magnetic observations of parahydrogen hyperpolarization dynamics, Proceedings of the National Academy of Sciences (2024). DOI: 10.1073/pnas.2410209121
Citation: Atomic sensors reveal hidden dynamics of molecular polarization (October 16, 2024) from https://phys.org/news/2024-10-atomic-sensors-unveil-hidden-dynamics.html 2024 Retrieved October 16,
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