High-resolution magnetic resonance imaging (MRI) machines can work better by changing the structure of radio probes from coils to antennas.

How can you make a high-frequency MRI machine more precise? By taking an electrical engineering approach to creating a better, uniform magnetic field.

In a new study published in Transactions on Microwave Theory and Techniques, researchers have discovered that radio frequency probes with structures inspired by microstrip patch antennas increase MRI resolution in high-frequency MRI machines, when compared to conventional surface coils used now.

"When frequencies become higher, wavelengths become shorter, and your magnetic field loses uniformity," says Elena Semouchkina, an associate professor of electrical and computer engineering at Michigan Tech. "Uniformity is important for high resolution images, so we proposed a new approach to developing these probes."

Semouchkina explains that kind of antenna that you see on the top of a building isn't quite the same thing used here, but instead, the team's design was inspired by microstrip patch antenna (MPA). The design is relatively simple: MPAs are made of a flat piece of metal grounded by a larger piece of metal. They're cheap, simple, and easy to make, which is why they're so often used in telecommunications.

MRIs work by issuing radio frequency pulses in a magnetic field via probes with coils or bird-cage like structures. That's then used to create an image.

But those conventional coils have frequency limits: too high and they can't create uniformed magnetic fields at the volume researchers need.

MPAs are an alternative where waves oscillate in the cavity formed between the patch and ground plane electrodes, which are accompanied by currents in the patch electrode and, respectively, oscillating magnetic fields around the patch, providing a magnetic field that is both even and strong.

"While the complexity of birdcage coils increases with the increase in operation frequency, patch-based probes can provide quality performance in the higher microwave range while still having a relatively simple structure," Semouchkina says. They also showed smaller radiation losses, making them competitive with, even better, than conventional coils.

Because of the damage high-frequency radio waves cause to humans, the study was limited to high frequency machines - not the metal tube that we're used to seeing in hospitals and medical centers. Humans can only sustain frequencies up to seven Teslas, but ultrahigh fields up to 21.1 Teslas can be used in testing on animal models, and in tissue samples.

Semouchkina is already known for her work involving invisibility cloaks, which involve redirecting electromagnetic waves around an area to hide an object. "We use some of the same approaches that we developed in cloaking devices here, like making antenna smaller," she said.

Research paper

Related Links
Michigan Technological University
Satellite-based Internet technologies

Tweet

Thanks for being here; We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain. With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords. Our news coverage takes time and effort to publish 365 days a year. If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Contributor $5 Billed Once credit card or paypal		SpaceDaily Monthly Supporter $5 Billed Monthly paypal only

Apple Watch supplier under fire over China student labour
Washington (AFP) Oct 30, 2018
Apple is investigating a factory in southwest China after a labour rights group said the tech giant's supplier forced student workers to work "like robots" to assemble its popular Apple Watch. Many were compelled to work in order to get their vocational degrees and had to do night shifts, according to an investigation by Hong Kong-based NGO Students and Scholars Against Corporate Misbehaviour (SACOM). SACOM interviewed 28 students at the plant in Chongqing municipality over the summer, and all o ... read more