Software improvements help MRIs diagnose joint hardware problems
1:14 a.m. Tuesday, November 21, 2006
Two years ago, Bill Heaton had both of his knees replaced. But he didn't have long-lasting relief.
"I expected some pain, but this was kind of severe discomfort," Heaton said.
X-rays of the implants didn't reveal any problems.
"We really wouldn't necessarily want to go and operate because we didn't know what we were operating on," Dr. Geoffrey Westrich said.
So the doctor asked Bill to get an MRI, even though the magnet usually makes a mess of the image.
Fast Facts
- Osteoarthritis affects 21 million people in the U.S. Another 2.1 million Americans have rheumatoid arthritis.
- About 435,000 patients have hip or knee replacements each year.
- When a patient with an artificial joint has pain, X-rays may not be able to pinpoint the cause of the problem.
- Doctors have traditionally avoided MRI in patients with joint prostheses because of fear the metal components may be damaged or cause injury in the magnetic field.
- Researchers say patients with newer artificial joints can often have an MRI, and refinements in software are producing much clearer, detailed images.
To learn more about arthritis or joint replacement surgery, visit the Arthritis Foundation Web site. For more information about magnetic resonance imaging (MRI), visit the Radiological Society of North America Web site.
"What Hospital for Special Surgery MRI facility has done, really championed by Dr. Hollis Potter, is she's worked on the MRI software to basically reduce the amount of artifact and enhance the detail," Westrich said.
"The minute the patient goes into the magnet, that's when we start our work. And we change the whole protocol, the normal way that the images are obtained," Potter said.
An MRI uses a strong magnet. When metal from an implant sits next to soft tissue from the body, it creates a "frequency shift."
"That generates an artifact that looks like a big blob of black and a big blob of white," Potter said.
After several years of research, Potter was finally able to manipulate the MRIs scanning settings for a clearer image.
"And so this MRI was very useful in telling me exactly what the problem is and making the specific diagnosis," Westrich said.
The MRI showed Bill's knee cap needed a new part and some rebalancing.
"He was able to make a diagnosis that I felt really comfortable and confident about going into surgery," Bill said.
Now, three weeks later, he's pain free.
For more information, contact the Hospital for Special Surgery, Department of Radiology and Imaging at (212) 606-1015.
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