(SACRAMENTO) In a proof-of-concept study published in the British Journal of Radiology, UC Davis clinicians and researchers have shown that a new, low-field 0.55T MRI (magnetic resonance imaging) system can create clear videos of moving wrists. This emerging technology could provide important insights to improve diagnoses and better understand wrist anatomy.

“Moving images give us a new tool to diagnose wrist dysfunction, either during motion or when there is load on the joint,” said Abhijit Chaudhari, professor in the Department of Radiology and interim director of the UC Davis Imaging Research Center. “The wrist is highly complex, so the ability to visualize motion will have enormous impact.”

For decades, MRIs have provided excellent static images to inform diagnoses. However, the wrist has eight carpal bones and many ligaments, which can make it difficult for orthopaedists to assess motional dysfunction (also called dynamic instability) using still images alone. In some cases, patients have chronic wrist pain, but their doctors simply cannot determine the cause.
Wanting to solve this problem, Chaudhari, Robert Szabo, distinguished professor of orthopaedics and chief emeritus of hand and upper extremity surgery, and Robert Boutin, musculoskeletal radiologist and professor of radiology at Stanford University, have been working on real-time MRI for more than a decade. Their original efforts, in 2013, produced a meager two to three frames per second. Though ideal for still images, powerful three Tesla (3T) MRI machines produce visual artifacts, such as bands without signal, that can obscure wrist anatomy.

“We were doing all our work on 3T systems, and we realized we could not do much better because these system have limitations,” said Chaudhari. “Whenever movement is conducted within a high-field strength magnet, you disturb the magnetic field a lot, and that created artifacts in images that disrupt our ability to assess the joints.”

Developing a Better System
Chaudhari, Szabo and Boutin collaborated with Krishna Nayak, who directs the Dynamic Imaging Science Center at the University of Southern California and is a co-author on the new paper. Nayak and colleagues received a National Science Foundation grant to develop a 0.55T MRI system specifically for dynamic imaging.

In the current study, the team showed the 0.55T machine could produce diagnostic-quality images, either as stills or short, 78 frame-per-second movies. In addition, real-time MRI was incredibly fast. The research team produced high-quality videos in 5 seconds or less. This rapid capture means real-time MRI could improve care without adding significant cost.

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