title: MR T2 values of the knee menisci in the healthy young population: zonal and sex differences.
abstract: OBJECTIVE
  The magnetic resonance (MR) T2 value of the cartilage, which has been shown in the articular cartilage to correlate with collagen fiber orientation and water content, may be helpful for early detection of chondropathy. However, the measurement and significance of MR T2 value for knee meniscus have not been well established. The purpose of this study was to investigate whether the MR T2 values in the diverse zones of the posterior horn of the knee meniscus differ between sexes in a young healthy population.
  
  
  METHODS
  Twenty healthy volunteers, 10 men and 10 women (aged from 22 to 32 years), were enrolled for MR imaging of the right knee menisci. The T2 values of the posterior horns of the medial and lateral knee menisci were measured for the white zone, red/white zone, and red zone on images acquired with fat-suppressed multislice turbo spin-echo sequence at 3.0 T.
  
  
  RESULTS
  The T2 value, with medial and lateral menisci considered together, increased significantly from the inner white zone (T2=8.02+/-0.60 ms), to the red/white zone (T2=8.78+/-0.99 ms), and to the outer red zone (T2=12.22+/-0.92 ms) of the posterior horns of the menisci (P<0.001). A generalized estimating equation method and multiple linear regression model showed that the T2 values averaged for the medial and lateral menisci together in the red and red/white zones were significantly lower in men than in women by 1.320 ms (P=0.002) and 0.865 ms (P<0.001), respectively, while the white zone showed no significant difference (P=0.694) between men (8.08+/-0.63 ms) and women (7.98+/-0.60 ms).
  
  
  CONCLUSIONS
  Zonal and sex differences in the MR T2 values in the posterior horns of the knee menisci exist in the young healthy population. These differences may be associated with sex differences in the occurrence of knee osteoarthritis.
authors.affiliation: Graduate Institute of Biomedical Electronics and Bioinformatics, Department of Radiology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, Republic of China.
authors.forename: P-H
authors.initials: PH
authors.lastname: Tsai
authors.forename: M-C
authors.initials: MC
authors.lastname: Chou
authors.forename: H-S
authors.initials: HS
authors.lastname: Lee
authors.forename: C-H
authors.initials: CH
authors.lastname: Lee
authors.forename: H-W
authors.initials: HW
authors.lastname: Chung
authors.forename: Y-C
authors.initials: YC
authors.lastname: Chang
authors.forename: G-S
authors.initials: GS
authors.lastname: Huang