Comprehensive zonal assessment of meniscal degeneration using quantitative UTE MRI

Knee menisci consist of three zones-red-red (RR), red-white (RW), and white-white (WW) zones, which may be differentially affected by osteoarthritis (OA). Zone-specific quantitative imaging techniques are valuable in understanding OA progression. The study utilized a comprehensive set of ultrashort-echo-time (UTE) MRI sequences, including UTE-T₁, UTE-magnetization-transfer (UTE-MT), UTE-T_1ρ, and UTE-T₂*, to assess compositional differences across meniscal zones and their changes with early degeneration.

Sixty-two volunteers (mean-age 55±17 years; 30 females; 46 patients with radiographic OA) participated in the study. UTE techniques were employed to quantify T₁, macromolecular fraction (MMF), T_1ρ, and T₂* in the meniscus within RR, RW, and WW zones. Clinical MRI classified meniscal degeneration into three grades. Regions-of-interest (ROIs) were placed within three zones in four different meniscal regions: the anterior and posterior horns of the lateral meniscus and those of the medial meniscus in each participant. Statistical comparisons were performed between meniscal zones and across degeneration grades.

A total of 178 meniscal regions were analyzed, with 65 classified as grade-1 (normal), 80 as grade-2 (mild-degeneration), and 33 as grade-3 (advanced-degeneration). Significant differences in all UTE measurements were clearly observed between the three zones in normal menisci. These differences became less distinct with increasing degeneration. Furthermore, within each zone, T₁, T_1ρ, and T₂* significantly increased with increasing degeneration, whereas MMF decreased significantly.

The study highlights the potential of UTE measurements to differentiate normal meniscal zonal composition and detect early changes due to degeneration, offering a promising tool for comprehensive knee-OA assessment and treatment monitoring.