title: Feasibility and reproducibility of relaxometry, morphometric, and geometrical measurements of the hip joint with magnetic resonance imaging at 3T.
abstract: OBJECTIVE
  To test the feasibility of in vivo magnetic resonance T(1rho) relaxation time measurements of hip cartilage, and quantify the reproducibility of hip cartilage thickness, volume, T(2), T(1rho), and size of femoral head measurements.
  
  
  METHODS
  The hip joint of five human healthy volunteers, one subject with mild hip osteoarthritis (OA) and one subject with advanced hip OA, was imaged with magnetic resonance imaging (MRI) at 3T. Hip cartilage thickness, volume, T(1rho), and T(2) were quantified, as well as the size of the femoral head. All imaging and analysis procedures were performed twice for the healthy volunteers to assess reproducibility.
  
  
  RESULTS
  In vivo MR T(1rho) measurements of hip cartilage at 3T were feasible as demonstrated by high quality images and relaxation time maps. High levels of reproducibility were obtained for measurements of hip cartilage thickness (CV(SD) = 2.19%), volume (CV(SD) = 3.5%), T(2) (CV(SD) = 5.89%), T(1rho) (CV(SD) = 2.03%), and size of femoral head (CV(SD) = 0.49%). Mean T(2) and T(1rho) relaxation time values for human healthy subjects were 28.38 (+/-2.66) msec and 38.72 (+/-3.84) msec, respectively. Mean T(2) and T(1rho) relaxation time values for subjects with OA were 34.78 (+/-8.36) msec and 44.07 (+/-0.99) msec, respectively. T(2) and T(1rho) values increased from the deep to the superficial layers.
  
  
  CONCLUSIONS
  Qualitative and quantitative results indicate that the MRI techniques presented in this study may be applied clinically to patients with OA of the hip to investigate these parameters at different stages of disease.
authors.affiliation: Department of Radiology, University of California-San Francisco, 1700 4th Street, San Francisco, CA 94158, USA. Julio.Carballido@radiology.ucsf.edu
authors.forename: Julio
authors.initials: J
authors.lastname: Carballido-Gamio
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Link
authors.forename: Xiaojuan
authors.initials: X
authors.lastname: Li
authors.forename: Eric T
authors.initials: ET
authors.lastname: Han
authors.forename: Roland
authors.initials: R
authors.lastname: Krug
authors.forename: Michael D
authors.initials: MD
authors.lastname: Ries
authors.forename: Sharmila
authors.initials: S
authors.lastname: Majumdar
mesh_terms: D000328:Adult; D002358:Cartilage, Articular / Q000033:anatomy & histology; D005240:Feasibility Studies; D005260:Female; D005270:Femur Head / Q000033:anatomy & histology; D006621:Hip Joint / Q000033:anatomy & histology*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D010003:Osteoarthritis / Q000473:pathology; D015203:Reproducibility of Results