A new spin on MRI may allow for new medical diagnostics

Now, a team of researchers at the University of Tsukuba have demonstrated a proof-of-concept method for equipping a conventional MRI machine with the capability to image 23Na by installing a cross band RF repeater system. This is a device that receives signals at a certain frequency and rebroadcast at a different one. "The RF repeater, which is a commonly used device in amateur radio, can be placed directly inside the magnet bore of an existing MRI machine as a cost-effective upgrade," explains author Professor Yasuhiko Terada. This allows the frequency produced by 23Na, which is around 17 MHz, to be detected by the coils tuned at the 64 MHz of MRI.

The research team tested the system with a saline "phantom" and an anesthetized mouse. Even though the resulting signal was much lower compared with custom-built 23Na machines, it could be amplified to produce comparable images. "Watching the motion of sodium ions inside the body provides detailed metabolic information not available from conventional MRI images," Professor Terada says. 23Na imaging has already been shown to be useful for applications involving the kidney, owing to its large sodium concentration, as well as the brain and heart. This approach may substantially reduce health care costs by providing completely new abilities to existing machines without requiring a complete refurbishment.

The work is published in Magnetic Resonance in Medical Sciences as "Development of an add-on 23Na-MRI radiofrequency platform for a 1H-MRI system using a crossband repeater: proof-of-concept" (DOI:10.2463/mrms.tn.2021-0094).

https://www.jstage.jst.go.jp/article/mrms/advpub/0/advpub_tn.2021-0094/_article