title: T1rho MRI relaxation in knee OA subjects with varying sizes of cartilage lesions.
abstract: BACKGROUND
  The purpose of this investigation is to evaluate the T(1ρ) relaxation times of articular cartilage surrounding focal defects in the tibiofemoral joint.
  
  
  METHODS
  Quantitative cartilage assessment was performed using 3T MRI with T(1ρ) mapping in 19 healthy individuals and 44 OA patients. Sagittal T2-weighted fast spin echo (FSE) images were acquired for lesion assessment. Differences were determined using analysis of variance (ANOVA).
  
  
  RESULTS
  Cartilage lesions were found in 37% of controls, and 93% of OA patients. Meniscal tears were found in 16% of controls and 57% of OA patients. We observed no difference in T(1ρ) relaxation times when comparing cartilage immediately surrounding a focal defect, and the remaining cartilage within that compartment. The medial femoral condyle (MFC) had the highest incidence of cartilage defects. MFC and medial meniscus posterior horn T(1ρ) were higher in subjects having multiple focal lesions (p = 0.048, pb 0.001 respectively) and extensive full thickness lesions (p = 0.009, pb 0.001 respectively) compared to subjects with no MFC defects. Significant elevations in T(1ρ) of the adjacent compartment (medial tibia) and medial meniscus were observed in subjects with MFC lesions.
  
  
  CONCLUSIONS
  Increased relaxation times in the involved compartment as well as the adjacent compartment and associated meniscus underscore the interdependence of these structures at bearing load. However, no differences in cartilage composition immediately surrounding a defect were noted. Finally, an association was observed between cartilage defects and meniscal damage in advanced disease.
  
  
  CONCLUSIONS
  Cartilage defects were not associated with degeneration in the immediately adjacent cartilage.
authors.affiliation: Department of Physical Therapy and Rehabilitation Science, University of California, San Francisco, CA, USA. richard.souza@ucsf.edu
authors.forename: Richard B
authors.initials: RB
authors.lastname: Souza
authors.forename: Brian T
authors.initials: BT
authors.lastname: Feeley
authors.forename: Zinta A
authors.initials: ZA
authors.lastname: Zarins
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Link
authors.forename: Xiaojuan
authors.initials: X
authors.lastname: Li
authors.forename: Sharmila
authors.initials: S
authors.lastname: Majumdar
mesh_terms: D000328:Adult; D002358:Cartilage, Articular / Q000293:injuries* / Q000473:pathology; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008592:Menisci, Tibial / Q000473:pathology; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000473:pathology*; D000070600:Tibial Meniscus Injuries