New Method of Osteoarthritis Detection Examines Sodium Ions

By examining sodium ions in cartilage of the knee joint, researchers at New York University have provided a possible non-invasive method of diagnosing osteoarthritis in its early stages.

The research is published in the Journal of Magnetic Resonance.

The loss of glycosaminogycans (GAGs) in cartilage tissues typically marks the onset of osteoarthritis and intervertebral disc degeneration. Concentrations of sodium ions can reveal the location of GAGs in cartilage tissues. By examining sodium ions, researchers can map GAG concentrations, which can help diagnose and monitor diseases and determine the efficacy of drug therapies.

However, existing techniques for GAG monitoring cannot directly map GAG concentrations and sometimes require contrast agents be administered to reveal the locations. Since sodium ions are already in cartilage, researchers have sought to measure these using special non-invasive MRI techniques.

Such attempts have not been able to isolate ions in different parts of the knee area, nor make clear-cut distinctions between signals of slow motion sodium ions in the cartilage from those of free sodium ions in synovial fluid and joint effusion in the knee joint.

Researchers from NYU attempted to better target where the sodium concentrations reside by focusing on the differences in the magnetic behavior of sodium ions in different environments. The team developed a new method to isolate two pools of sodium ions and obtained images where the sodium signals appear exclusively from regions with cartilage tissue.

This sodium MRI method provided a non-invasive way to diagnose osteoarthritis in its early stages and also helped calibrate other, less direct measures of cartilage assessments.