title: Responsiveness of quantitative cartilage measures over one year in knee osteoarthritis: comparison of radiography and MRI assessments.
abstract: OBJECTIVE
  To directly compare the responsiveness of quantitative imaging measures of disease progression in knee osteoarthritis (OA). In the medial compartment of the knee comparison was made between: 1) radiographic joint space narrowing (JSN); 2) global quantitative magnetic resonance imaging (qMRI) of cartilage volume; 3) regional qMRI of cartilage thickness; and 4) regional analysis using an ordered value (OV) methodology.
  
  
  METHODS
  3T MRI and weight-bearing radiography of the knees were performed at baseline and 1-year timepoints in 23 subjects (mean age 63 years) with symptomatic knee OA. Standardized response means (SRM) were calculated for each measure. Statistical analysis to determine significance of change between timepoints was performed with a two-tailed Student's t-test (JSN, global, regional analysis) and nonparametric Mann-Whitney test (ordered values).
  
  
  RESULTS
  At 1 year, global cartilage volume losses of 2.3% (SRM -0.44) in the medial tibia and 6.9% in the medial femur (SRM -0.74) were recorded. SRM for JSN was -0.46. Regional analysis revealed largest reductions in cartilage thickness in the external (SRM -0.84) weight-bearing subregion of the medial femur and in the posterior subregion of the medial tibia (SRM -0.79). OV analysis in the medial compartment revealed areas of cartilage thinning (four ranked OV) and cartilage thickening (two ranked OV).
  
  
  CONCLUSIONS
  The MRI OV approach proved to be a superior analysis tool for detecting changes in cartilage morphology over a 1-year period. Radiographically defined JSN was found to be the least responsive measurement method of knee OA disease progression.
authors.affiliation: Department of Radiology, Westmead Hospital, Westmead, Australia; Discipline of Medical Radiation Sciences, Faculty of Health Sciences, University of Sydney, Sydney, Australia.
authors.forename: Megan S
authors.initials: MS
authors.lastname: Cromer
authors.forename: Roger M
authors.initials: RM
authors.lastname: Bourne
authors.forename: Marlene
authors.initials: M
authors.lastname: Fransen
authors.forename: Roger
authors.initials: R
authors.lastname: Fulton
authors.forename: Shih-Chang
authors.initials: SC
authors.lastname: Wang
mesh_terms: D000368:Aged; D002356:Cartilage / Q000473:pathology*; D002358:Cartilage, Articular / Q000473:pathology*; D015331:Cohort Studies; D018450:Disease Progression; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging* / Q000473:pathology*; D011859:Radiography; D016474:Weight-Bearing
keywords: JSN; cartilage thickness; knee osteoarthritis; quantitative magnetic resonance imaging