title: Texture analysis of cartilage T2 maps: individuals with risk factors for OA have higher and more heterogeneous knee cartilage MR T2 compared to normal controls--data from the osteoarthritis initiative.
abstract: BACKGROUND
  The goals of this study were (i) to compare the prevalence of focal knee abnormalities, the mean cartilage T2 relaxation time, and the spatial distribution of cartilage magnetic resonance (MR) T2 relaxation times between subjects with and without risk factors for Osteoarthritis (OA), (ii) to determine the relationship between MR cartilage T2 parameters, age and cartilage morphology as determined with whole-organ magnetic resonance imaging scores (WORMS) and (iii) to assess the reproducibility of WORMS scoring and T2 relaxation time measurements including the mean and grey level co-occurrence matrix (GLCM) texture parameters.
  
  
  METHODS
  Subjects with risk factors for OA (n = 92) and healthy controls (n = 53) were randomly selected from the Osteoarthritis Initiative (OAI) incidence and control cohorts, respectively. The specific inclusion criteria for this study were (1) age range 45-55 years, (2) body mass index (BMI) of 19-27 kg/m2, (3) Western Ontario and McMaster University (WOMAC) pain score of zero and (4) Kellgren Lawrence (KL) score of zero at baseline. 3.0 Tesla MR images of the right knee were analyzed using morphological gradings of cartilage, bone marrow and menisci (WORMS) as well as compartment specific cartilage T2 mean and heterogeneity. Regression models adjusted for age, gender, and BMI were used to determine the difference in cartilage parameters between groups.
  
  
  RESULTS
  While there was no significant difference in the prevalence of knee abnormalities (cartilage lesions, bone marrow lesions, meniscus lesions) between controls and subjects at risk for OA, T2 parameters (mean T2, GLCM contrast, and GLCM variance) were significantly elevated in those at risk for OA. Additionally, a positive significant association between cartilage WORMS score and cartilage T2 parameters was evident.
  
  
  CONCLUSIONS
  Overall, this study demonstrated that subjects at risk for OA have both higher and more heterogeneous cartilage T2 values than controls, and that T2 parameters are associated with morphologic degeneration.
authors.affiliation: Department of Radiology and Biomedical Imaging, University of California San Francisco, 1700 4th Street, Suite 203, San Francisco, CA 94107, USA. gabby.joseph@ucsf.edu
authors.forename: Gabby B
authors.initials: GB
authors.lastname: Joseph
authors.forename: Thomas
authors.initials: T
authors.lastname: Baum
authors.forename: Julio
authors.initials: J
authors.lastname: Carballido-Gamio
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Nardo
authors.forename: Warapat
authors.initials: W
authors.lastname: Virayavanich
authors.forename: Hamza
authors.initials: H
authors.lastname: Alizai
authors.forename: John A
authors.initials: JA
authors.lastname: Lynch
authors.forename: Charles E
authors.initials: CE
authors.lastname: McCulloch
authors.forename: Sharmila
authors.initials: S
authors.lastname: Majumdar
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Link
mesh_terms: D002358:Cartilage, Articular / Q000473:pathology*; D015331:Cohort Studies; D016208:Databases, Factual; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000175:diagnosis* / Q000453:epidemiology* / Q000473:pathology; D012307:Risk Factors