OBJECTIVETo evaluate T2 mapping of the healthy knee articular cartilage in different subregions using a magnetic resonance segmentation.

METHODST2 mapping was performed to 77 healthy tibiofemoral cartilages, which were divided into group H1 ( <40 years old) and group H2 (≥ 40 years old). T2 values of cartilage IN 10 subregions based on the Whole-Organ Magnetic Resonance Imaging Score (WORMS) segmentation and body mass index (BMI) were calculated. T2 values of cartilage in 10 subregions were compared. The association between T2 value and BMI/age was analyzed. The intra- and inter-observer reproducibility of measurement was calculated.

RESULTSThe T2 values of all the subregions ranged 40. 3-53.5 ms. T2 values of group H2 were significantly higher than those in group H1 (P ≤ 0.032) except in posterior lateral femoral subregion. The inter-subregion differences within group were significant (P ≤ 0.001). The inter-gender differences were significant only in posterior medial tibial subregion of group H2 (P=0.048). No correlation of T2 values with BMI was found except in cetral lateral tibial subregion of group H2 (P=0.050, R=0.308). T2 values were correlated with age in anterior medial (P=0.004, R=-0.467) and anterior lateral P = 0.024, R=-0.375) tibial subregion of group H1 , and in all tibial subregion except anterior lateral tibial subregion of group H2 , and central medial femoral subregion of group H2 (P=0.004~0.015, R=0.376~0.437). The correlation coefficients for intra- and inter-observer of measurement showed good reproducibility (R>0.809, P ≤ 0.005).

CONCLUSIONT2 mapping of the healthy knee articular cartilage based on the WORMS segmentation can effectively reflect the changes and correlations of T2 values with risk factors by focusing on the functional weight-bearing subregions.