title: Magnetic resonance imaging of osteophytic, chondral, and subchondral structures in a surgically-induced osteoarthritis rabbit model.
abstract: OBJECTIVE
  This study aimed to assess changes in osteophytic, chondral, and subchondral structures in a surgically-induced osteoarthritis (OA) rabbit model in order to correlate MRI findings with the macroscopic progress of OA and to define the timepoint for disease status in this OA model.
  
  
  METHODS
  The OA model was constructed by surgery in thirty rabbits with ten normal rabbits serving as controls (baseline). High-resolution three-dimensional MRI using a 1.5-T coil was performed at baseline, two, four, and eight weeks post-surgery. MRIs of cartilage lesions, subchondral bone lesions, and osteophyte formations were independently assessed by two blinded radiologists. Ten rabbits were sacrificed at baseline, two, four, and eight weeks post-surgery, and macroscopic evaluation was independently performed by two blinded orthopedic surgeons.
  
  
  RESULTS
  The signal intensities and morphologies of chondral and subchondral structures by MRI accurately reflected the degree of OA. Cartilage defects progressed from a grade of 0.05-0.15 to 1.15-1.30 to 1.90-1.97 to 3.00-3.35 at each successive time point, respectively (p<0.05). Subchondral bone lesions progressed from a grade of 0.00 to 0.78-0.90 to 1.27-1.58 to 1.95-2.23 at each successive time point, respectively (p = 0.000). Osteophytes progressed from a size (mm) of 0.00 to 0.87-1.06 to 1.24-1.87 to 2.21-3.21 at each successive time point, respectively (p = 0.000).
  
  
  CONCLUSIONS
  Serial observations revealed that MRI can accurately detect the progression of cartilage lesions and subchondral bone edema over an eight-week period but may not be accurate in detecting osteophyte sizes. Week four post-surgery was considered the timepoint between OA-negative and OA-positive status in this OA model. The combination of this OA model with MRI evaluation should provide a promising tool for the pre-clinical evaluation of new disease-modifying osteoarthritis drugs.
authors.affiliation: State Key Laboratory of Ultrasound Engineering in Medicine Co-Founded by Chongqing and the Ministry of Science and Technology, College of Biomedical Engineering, Chongqing Medical University, Chongqing, China; Department of Rehabilitation Medicine, the Second Affiliated Hospital, Chongqing Medical University, Chongqing, China.
authors.forename: Lang
authors.initials: L
authors.lastname: Jia
authors.affiliation: State Key Laboratory of Ultrasound Engineering in Medicine Co-Founded by Chongqing and the Ministry of Science and Technology, College of Biomedical Engineering, Chongqing Medical University, Chongqing, China.
authors.forename: Jinyun
authors.initials: J
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Ultrasound Engineering in Medicine Co-Founded by Chongqing and the Ministry of Science and Technology, College of Biomedical Engineering, Chongqing Medical University, Chongqing, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Ultrasound Engineering in Medicine Co-Founded by Chongqing and the Ministry of Science and Technology, College of Biomedical Engineering, Chongqing Medical University, Chongqing, China.
authors.forename: Yingjiang
authors.initials: Y
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Ultrasound Engineering in Medicine Co-Founded by Chongqing and the Ministry of Science and Technology, College of Biomedical Engineering, Chongqing Medical University, Chongqing, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Ultrasound Engineering in Medicine Co-Founded by Chongqing and the Ministry of Science and Technology, College of Biomedical Engineering, Chongqing Medical University, Chongqing, China.
authors.forename: Wenzhi
authors.initials: W
authors.lastname: Chen
mesh_terms: D000818:Animals; D001169:Arthritis, Experimental / Q000473:pathology* / Q000601:surgery*; D002356:Cartilage / Q000473:pathology; D018450:Disease Progression; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D015588:Observer Variation; D054850:Osteophyte / Q000473:pathology; D011446:Prospective Studies; D011817:Rabbits; D013997:Time Factors