title: Longitudinal analysis of MR spin-spin relaxation times (T2) in medial femorotibial cartilage of adolescent vs mature athletes: dependence of deep and superficial zone properties on sex and age.
abstract: OBJECTIVE
  Cartilage spin-spin magnetic resonance imaging (MRI) relaxation time (T2) represents a promising imaging biomarker of "early" osteoarthritis (OA) known to be associated with cartilage composition (collagen integrity, orientation, and hydration). However, no longitudinal imaging studies have been conducted to examine cartilage maturation in healthy subjects thus far. Therefore, we explore T2 change in the deep and superficial cartilage layers at the end of adolescence.
  
  
  METHODS
  Twenty adolescent and 20 mature volleyball athletes were studied (each 10 men and 10 women). Multi-echo spin-echo (MESE) images were acquired at baseline and 2-year follow-up. After segmentation, cartilage T2 was calculated in the deep and superficial cartilage layers of the medial tibial (MT) and the central, weight-bearing part of the medial femoral condyle (cMF), using five echoes (TE 19.4-58.2 ms).
  
  
  RESULTS
  16 adolescent (6 men, 10 women, baseline age 15.8 ± 0.5 years) and 17 mature (nine men, eight women, age 46.5 ± 5.2 years) athletes had complete baseline and follow-up images of sufficient quality to compute T2. In adolescents, a longitudinal decrease in T2 was observed in the deep layers of MT (-2.0 ms; 95% confidence interval (CI): [-3.4, -0.6] ms; P < 0.01) and cMF (-1.3 ms; [-2.4, -0.3] ms; P < 0.05), without obvious differences between males and females. No significant change was observed in the superficial layers, or in the deep or superficial layers of the mature athletes.
  
  
  CONCLUSIONS
  In this first pilot study on quantitative imaging of cartilage maturation in healthy, athletic subjects, we find evidence of cartilage compositional change in deep cartilage layers of the medial femorotibial compartment in adolescents, most likely related to organizational changes in the collagen matrix.
authors.affiliation: Institute of Anatomy, Paracelsus Medical University, Salzburg, Austria.
authors.forename: W
authors.initials: W
authors.lastname: Wirth
authors.affiliation: Institute of Anatomy, Paracelsus Medical University, Salzburg, Austria. Electronic address: felix.eckstein@pmu.ac.at.
authors.forename: F
authors.initials: F
authors.lastname: Eckstein
authors.affiliation: Julius Wolff Institute, Charité - Universitätsmedizin Berlin, Center for Sports Science and Sports Medicine Berlin, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Boeth
authors.affiliation: Department of Radiology, Charité - Universitätsmedizin Berlin, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Diederichs
authors.affiliation: Institute of Anatomy, Paracelsus Medical University, Salzburg, Austria.
authors.forename: M
authors.initials: M
authors.lastname: Hudelmaier
authors.affiliation: Julius Wolff Institute, Charité - Universitätsmedizin Berlin, Center for Sports Science and Sports Medicine Berlin, Germany.
authors.forename: G N
authors.initials: GN
authors.lastname: Duda
mesh_terms: D000293:Adolescent; D041923:Adolescent Development; D000328:Adult; D000367:Age Factors; D056352:Athletes; D002358:Cartilage, Articular / Q000033:anatomy & histology / Q000254:growth & development*; D005260:Female; D005269:Femur / Q000033:anatomy & histology / Q000254:growth & development*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007719:Knee Joint / Q000033:anatomy & histology / Q000254:growth & development*; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D012737:Sex Factors; D013977:Tibia / Q000033:anatomy & histology / Q000254:growth & development*
keywords: Cartilage; Collagen; Development; Knee; Maturation; Spin–spin (T2) relaxation time