MRIs Receive a Natural Boost

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mri gets natural boost

Magnetic resonance imaging (MRI) is an imaging method that is widely used in medical practice to produce images of internal organs such as the heart, the lungs, the liver and even the brain. Since its introduction in 1977, the MRI has become a poster of clinical radiology, employed across the world to detect and identify health issues and complications in millions of patients on a global scale.

Yet in spite of its reputation and high regard, MRI is hindered by low sensitivity levels, which can be rectified by injecting patients with potentially toxic agents. Therefore, researchers from the École polytechnique fédérale de Lausanne (EPFL) have discovered a means of attaining high spatial and temporal resolution MRI using a safe compound that is internally and naturally produced within the human body.

MRI operates by altering the alignment of the body's hydrogen atoms, which are prone to magnetic fields. Usually, our body's atoms spin around arbitrarily, without any specific direction. During an MRI scan, a powerful magnet is used to produce a magnetic field that can be up to 40,000 times stronger than the Earth's. This causes around half the atoms to align towards the patient's head, while the other half align towards the feet.

The conflicting alignment of the body's atoms cancels out most of the background 'noise', since for every atom lined up one way there is one lined up the opposite way. However, a few atoms per million (still a large amount in total) line up in either direction without a cancelling equivalent. By reading out the energy levels of these atoms, the MRI computer can produce detailed images of the body, which can be critical in diagnosing disease.

One glaring weakness is the MRI’s low levels of sensitivity. Such an issue can be resolved with the use of hyperpolarization techniques, which consists of injecting patients with substrates that contain a stable carbon isotope that is almost perfectly aligned with the machine's magnetic field. However, the preparation of these contrast agents calls for the use of highly reactive chemicals called persistent radicals, which can be potentially toxic.

As a result, they must be also be filtered out before injection and call for supplemental pharmacological tests, all of which significantly lessens MRI contrast, and poses a danger to the patient.

A research team led by Arnaud Comment discovered a groundbreaking solution to this complication. They found that high resolution in contrast-enhanced MRI can still be attained with pyruvic acid, an organic chemical that occurs naturally in the body as a result of glucose breakdown, without the need or use of persistent radicals.

The researchers exposed frozen, pure pyruvic acid to ultraviolet light for an hour, which resulted in the generation of non-persistent radicals at a high concentration. The radicals involuntarily recombine to generate a solution only containing compounds that are naturally present in the body, but in much lower concentrations. It was used to perform high-resolution MRI on a mouse brain. The resulting images displayed detailed spatial and temporal resolution to the point of tracking the metabolism of pyruvic acid in the animal's brain.

The new hyperpolarization technique grants an entirely different and effective way to perform MRI with compounds that are not toxic, therefore decreasing or altogether eradicating potential health risks. Moreover, because it does not require filtering or additional tests, the method will have a significant reduction on the time and cost of contrast-enhanced MRI procedures, thereby improving the quality of the scans and diagnosis. The authors believe that the technique will be implemented as soon as possible into the clinical routine and call it "a substantial step forward toward clinical radiology free of side effects."


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