Value of Adding T2mapping Sequence to Routine MRI Protocol in Assessment of Knee Articular Cartilage in Early Osteoarthritis

Osteoarthritis (OA) is one of the most common degenerative joint diseases, affecting more than 500 million people worldwide (1), causing joint pain and stiffness, and negatively affecting quality of life . The knee is the most commonly affected joint, followed by the hand and hip (1).

It is important clinically to diagnose osteoarthritis in its early stages to prevent its inevitable progression (2) Routine MR imaging sequences used in the identification of knee osteoarthritis can assess articular cartilage morphology, but despite its accuracy for identifying deep hyaline cartilage defects which are considered irreversible cartilage degeneration with limited treatment options, it lacks sufficient sensitivity for early cartilage changes and low-grade chondral lesions which are the reversible stages for the potential alteration of the osteoarthritis progression(2).

T2 mapping of hyaline cartilage is an imaging technique for the qualitative and quantitative detection of the cartilage providing convincing color mapping and quantitative detection of the cartilage mainly regarding architecture and changes in water content, proteoglycan, and collagen matrix ultra-structure associated with early cartilage degeneration(3).

T2 mapping is a time constant describing the rate at which energy transfer occurs between water protons in a magnetic field (spin-spin interactions), leading to signal dephasing. In normal healthy articular cartilage, water protons are largely bound in place by a well-organized matrix of collagen fibers, allowing for rapid dephasing, and therefore low T2 values are seen(4). However, in osteoarthritic articular cartilage, the collagen fibers become disorganized, and there are more mobile water protons, resulting in high T2 values. (4).