title: T2 texture index of cartilage can predict early symptomatic OA progression: data from the osteoarthritis initiative.
abstract: OBJECTIVE
  There is an interest in using Magnetic Resonance Imaging (MRI) to identify pre-radiographic changes in osteoarthritis (OA) and features that indicate risk for disease progression. The purpose of this study is to identify image features derived from MRI T2 maps that can accurately predict onset of OA symptoms in subjects at risk for incident knee OA.
  
  
  METHODS
  Patients were selected from the Osteoarthritis Initiative (OAI) control cohort and incidence cohort and stratified based on the change in total Western Ontario and McMaster Universities Arthritis (WOMAC) score from baseline to 3-year follow-up (80 non-OA progression and 88 symptomatic OA progression patients). For each patient, a series of image texture features were measured from the baseline cartilage T2 map. A linear discriminant function and feature reduction method was then trained to quantify a texture metric, the T2 texture index of cartilage (TIC), based on 22 image features, to identify a composite marker of T2 heterogeneity.
  
  
  RESULTS
  Statistically significant differences were seen in the baseline T2 TIC between the non-progression and symptomatic OA progression populations. The baseline T2 TIC differentiates subjects that develop worsening of their WOMAC score OA with an accuracy between 71% and 76%. The T2 TIC differences were predominantly localized to a dominant knee compartment that correlated with the mechanical axis of the knee.
  
  
  CONCLUSIONS
  Baseline heterogeneity in cartilage T2 as measured with the T2 TIC index is able to differentiate and predict individuals that will develop worsening of their WOMAC score at 3-year follow-up.
authors.affiliation: Department of Orthopaedics and Rehabilitation, Division of Musculoskeletal Sciences, College of Medicine, The Pennsylvania State University, 30 Hope Drive, EC089, Hershey, PA 17033, USA. Electronic address: kurish@hmc.psu.edu.
authors.forename: K L
authors.initials: KL
authors.lastname: Urish
authors.forename: M G
authors.initials: MG
authors.lastname: Keffalas
authors.forename: J R
authors.initials: JR
authors.lastname: Durkin
authors.forename: D J
authors.initials: DJ
authors.lastname: Miller
authors.forename: C R
authors.initials: CR
authors.lastname: Chu
authors.forename: T J
authors.initials: TJ
authors.lastname: Mosher
mesh_terms: D002358:Cartilage, Articular / Q000473:pathology*; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007719:Knee Joint / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000175:diagnosis* / Q000473:pathology; D011379:Prognosis; D012720:Severity of Illness Index
keywords: Cartilage T2; Image biomarkers; MRI; Osteoarthritis; Signal texture; T2 heterogeneity