MRI detects knee injuries sooner

February 26, 2009 7:28:29 PM PST
Researchers at Stanford have developed a modified version of an MRI which allows them to see knee injuries in a new way, and possibly catch damage to the cartilage in its earliest stages.

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"I still feel pain intermittently," says patient Seungbum Koo. He not only knows how his knee feels now, he has a strong indication of how it's likely to feel in the future, including his chances of developing osteoarthritis from the ACL tear he suffered several years ago.

"There are some ares in the articular cartilage where the sodium signal is brighter than others areas," says Dr. Garry Gold of Stanford.

Dr. Gold has scanned Koo's knee and those of other volunteers with an MRI specially modified by engineers at Stanford. Starting with a rough prototype, the researchers developed a new type of coil -- or housing -- that changes what the MRI sees when it is placed over the knee.

Instead of the traditional MRI that keys in on molecules in the watery part of the tissue to create an overall image of the knee area, the new coil keys in on the presence of sodium inside the cartilage.

"This over here is the proton MRI, and this in red is the sodium MRI. The degree of color intensity on the red scale image indicates the amount of sodium in the cartilage," says Dr. Gold.

As the cartilage begins to soften and deteriorate, those sodium molecules become more scarce and the line on the scan becomes thinner.

"So the reason to do sodium MRI is we can see those very early changes in cartilage that indicate early onset of arthritis," says Dr. Gold.

Researchers say the information generated by the sodium scan could be used to provide more than just an early warning sign of osteoarthritis. It could lead to the development of new drugs to keep the cartilage in the knee from deteriorating in the first place.

"The hope with sodium MRI is we can see changes in the cartilage very quickly, allowing a drug manufacturer to determine if a compound is working or not, within a few months or perhaps even a few weeks," says Dr. Gold.

Dr. Gold has recruited volunteers for his study from the pool of Stanford athletes who have suffered knee injuries.

And like Seungbum Koo, the doctor believes those athletes will be able to monitor the effect those injuries have on the knee's cartilage, before the damage would ever show up on traditional MRI.

The images could also help physical therapists monitor rehabbing athletes by letting them see if a training program is causing damage to the cartilage, and possibly adjusting the routine.

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