Magnetic metamaterial amplifies MRI for clearer images in less time

Magnetic resonance imaging (MRI) is a great tool for diagnosing disease in different organs and tissues, but it can be costly and cumbersome. Now, engineers at the Boston University Photonics Center have developed a new device, small enough for a patient to wear inside the machine, that could boost the signal and provide higher-resolution images at lower magnetic strengths.

MRI may be safer than other imaging techniques like X-ray, but it's still not the most pleasant experience. Patients have to lie perfectly still for an hour or more, as a loud and claustrophobic machine scans their body. The latest MRI machines crank up the power of the magnetic field to get higher-resolution images, but that can play havoc on the patient's implanted devices or even dental fillings.

The new device could help boost the imaging power of the more common machines that use lower-strength magnetic fields. In theory, the team says the new device could eventually be used with much lower-field MRI devices, that in turn could make the process much cheaper and more accessible in places that currently can't afford the expensive systems.

The new device is a magnetic metamaterial, made up of an array of small cylinders called helical resonators. Each of these tubes stands about 3 cm (1.2 in) tall, and is made of a 3D-printed plastic shell wrapped in a coil of thin copper wire. These resonators amplify the magnetic field of the machine, significantly boosting the signal-to-noise ratio (SNR) and producing clearer images of the body in about half the time.

This metamaterial could be built into the bed that the patient lies on during the scan, or made into a wearable device that wraps around the head, abdomen or whatever other body part is the focus of the MRI.

To test it out, the researchers scanned chicken legs, tomatoes and grapes using their new metamaterial and a commercial strength MRI machine. Sure enough, they found that the metamaterial gave a 4.2-fold increase in the SNR. By comparison, the team says, getting images of the same quality without the new device would require scans of up to 13.9 times longer.

This isn't the only approach to shortening MRI times or improving the results. Other teams have tried using artificial intelligence, specialized algorithms or other metallic resonators, with varying results. Altogether, the long lie-down in an MRI machine may not be so uncomfortable for much longer.

The research was published in the journal Communications Physics.

Source: Boston University