title: Sequential change in T2* values of cartilage, meniscus, and subchondral bone marrow in a rat model of knee osteoarthritis.
abstract: BACKGROUND
  There is an emerging interest in using magnetic resonance imaging (MRI) T2* measurement for the evaluation of degenerative cartilage in osteoarthritis (OA). However, relatively few studies have addressed OA-related changes in adjacent knee structures. This study used MRI T2* measurement to investigate sequential changes in knee cartilage, meniscus, and subchondral bone marrow in a rat OA model induced by anterior cruciate ligament transection (ACLX).
  
  
  METHODS
  Eighteen male Sprague Dawley rats were randomly separated into three groups (n = 6 each group). Group 1 was the normal control group. Groups 2 and 3 received ACLX and sham-ACLX, respectively, of the right knee. T2* values were measured in the knee cartilage, the meniscus, and femoral subchondral bone marrow of all rats at 0, 4, 13, and 18 weeks after surgery.
  
  
  RESULTS
  Cartilage T2* values were significantly higher at 4, 13, and 18 weeks postoperatively in rats of the ACLX group than in rats of the control and sham groups (p<0.001). In the ACLX group (compared to the sham and control groups), T2* values increased significantly first in the posterior horn of the medial meniscus at 4 weeks (p = 0.001), then in the anterior horn of the medial meniscus at 13 weeks (p<0.001), and began to increase significantly in the femoral subchondral bone marrow at 13 weeks (p = 0.043).
  
  
  CONCLUSIONS
  Quantitative MR T2* measurements of OA-related tissues are feasible. Sequential change in T2* over time in cartilage, meniscus, and subchondral bone marrow were documented. This information could be potentially useful for in vivo monitoring of disease progression.
authors.affiliation: Imaging Research Center, Taipei Medical University, Taipei, Taiwan ; Department of Medical Imaging, Taipei Medical University Hospital, Taipei Medical University, Taipei, Taiwan.
authors.forename: Ping-Huei
authors.initials: PH
authors.lastname: Tsai
authors.forename: Herng-Sheng
authors.initials: HS
authors.lastname: Lee
authors.forename: Tiing Yee
authors.initials: TY
authors.lastname: Siow
authors.forename: Yue-Cune
authors.initials: YC
authors.lastname: Chang
authors.forename: Ming-Chung
authors.initials: MC
authors.lastname: Chou
authors.forename: Ming-Huang
authors.initials: MH
authors.lastname: Lin
authors.forename: Chien-Yuan
authors.initials: CY
authors.lastname: Lin
authors.forename: Hsiao-Wen
authors.initials: HW
authors.lastname: Chung
authors.forename: Guo-Shu
authors.initials: GS
authors.lastname: Huang
mesh_terms: D000818:Animals; D016118:Anterior Cruciate Ligament / Q000601:surgery; D001853:Bone Marrow / Q000000981:diagnostic imaging*; D002358:Cartilage, Articular / Q000000981:diagnostic imaging*; D005240:Feasibility Studies; D016014:Linear Models; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008592:Menisci, Tibial / Q000000981:diagnostic imaging*; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging*; D011859:Radiography; D051381:Rats; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results; D013997:Time Factors