MRI Method Diagnoses Osteoarthritis in its Earliest Stages

Newly developed medical imaging technology may provide clinicians with a long-awaited test for early diagnosis of osteoarthritis (OA).

Scientists from New York University (New York, NY, USA) presented their findings August 21, 2008, at the 236th National meeting of the American Chemical Society, held in New York, NY, USA. By far the most common form of arthritis, OA causes joint pain and disability for more than half of those over 65--nearly 21 million individuals in the United States.

Current diagnostic methods usually do not detect the disease until OA is in advanced stages when joint damage may already have occurred. A method for early diagnosis could open a window of opportunity for preventing or reducing permanent damage, particularly with evidence that dietary supplements such as glucosamine and chondroitin can stop additional joint degeneration, according to Alexej Jerschow, Ph.D., who reported on the research jointly with Ravinder R. Regatte, Ph.D.

"Our methods have the potential of providing early warning signs for cartilage disorders like osteoarthritis, thus potentially avoiding surgery and physical therapy later on,” stated Dr. Jerschow. "Also, the effectiveness of early preventative drug therapies can be better assessed with these methods.”

Especially common in the knee and hip, osteoarthritis damages cartilage, the tough, elastic material that cushions moving parts of joints. OA is the most typical reason for total hip and total knee replacement surgery. "It has all these painful consequences and makes it difficult to move--it results in a severe loss of quality of life for those who are affected by it,” stated Dr. Regatte.

The new imaging modality uses a modified form of magnetic resonance imaging (MRI) to determine the concentration of a polymer known as glycosaminoglycan (GAG), which holds lots of water and gives cartilage its tough, elastic properties. GAG also is a recognized biomarker for both osteoarthritis and degenerative disc disease--a common cause of back pain. According to Dr. Jerschow, a low concentration of GAG is known to correlate with the onset of osteoarthritis and other cartilage disorders.

The diagnostic agent "tags” the hydrogen atoms attached to the GAGs in a manner that makes them emit a signal that can captured up by a MRI machine to determine the concentration of GAG and assess cartilage health. Advanced OA is very easy to diagnose, Dr. Regatte pointed out. By then, however, joint replacement may be the only option. With early detection, physicians could prescribe dietary supplements, medication, or other measures to ward off further cartilage damage. "Given the lack of knowledge about OA, I think any method that is noninvasive and relatively easy to apply will be quite valuable. Not only do you address diagnosis, but you address how we can understand OA's mechanism,” said Dr. Jerschow.

The MRI scan could also be used to improve existing cartilage-enhancing drugs, according to Dr. Regatte. At present, it is difficult to assess the effectiveness of these drugs without a diagnostic tool to gauge their effects on cartilage. "There are drugs on the market for OA treatment, but no one really knows how effective they are. After having done the research, we got a lot of calls from pharmaceutical companies wanting to show that their drugs work,” remarked Dr. Jerschow.

The cost and time it takes for the cartilage test is about the same as a typical MRI, according to Dr. Regatte. Diagnosis could be given on a same day basis. "I really hope it will develop into the gold standard technique,” said Dr. Jerschow. "I'm pretty confident in saying that its one of the better methods out there for testing cartilage health.”

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