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Trick Knee: How Metal Joint Implants Are Messing Up MRIs

Hospital for Special Surgery, New York/GE Healthcare

Metal joint implants are wreaking havoc on the MRI images doctors use to determine treatment, but a new process improves picture quality.

Joint replacements for knees and hips are on the rise as our population gets older. But as these surgeries become more common, they're posing a new problem for doctors: getting accurate MRI results. 

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Orthopedic implants are often made of metallic substances, and it turns out that metal implants mess up Magnetic Resonance Imaging results.

GE Healthcare physicist Kevin Koch, a specialist in magnetic field research, says the implants make it hard for MRI machines to get clear images because the metal causes a distortion in the magnetic field.

“We actually use the magnetic field to encode signal...and we use that information in order to rebuild the image," Koch says. "Now when you put the metal inside the magnet and it creates these distortions, that information that we're using is now completely warped."

Koch’s team at the GE Healthcare headquarters in Waukesha figured out that they needed to change how to collect data that is picked up by the magnetic field. GE worked with Stanford University and Hospital for Special Surgery in New York.

The researchers decided to work around the magnetic field, not against it, and thus developed an improved imaging technology known as MAVRIC SL.

“What we did was we actually allowed the magnetic field to dictate the region of the image that we would image,” Koch says. “And what that does is that it allows us to select regions that have relatively little severity of distortion.”

Koch Quora.jpeg
Credit Quora
Kevin Koch

Essentially, the MAVRIC SL process takes multiple images and then combines them, using a unique de-blurring technique, to create a final composite image. Koch says this allows all needed areas to be imaged with limited distortion.

Patients will not notice a difference because it is a software change, not a machine change.

Koch says the research began more than six years ago. Currently there are a few pilot sites that are trying out the software. It will be available for purchase in a month or two.

(edited by Stephanie Lecci)