title: T1rho relaxation time of the meniscus and its relationship with T1rho of adjacent cartilage in knees with acute ACL injuries at 3 T.
abstract: OBJECTIVE
  The aim of this study was to assess the reproducibility of meniscus T1rho measurements, and to study T1rho relaxation time in the lateral meniscus (LM) and its relationship with adjacent cartilage T1rho in knees with acute anterior cruciate ligament (ACL) injuries at 3T magnetic resonance imaging.
  
  
  METHODS
  Quantitative assessment of the meniscus and cartilage was performed in 15 healthy controls and 16 ACL-injured patients using a T1rho mapping technique. All ACL-injured patients were imaged prior to surgery within 1-3 months of injury. The anterior and posterior horns of LM and medial meniscus (MM) were associated with partitioned weight-bearing cartilage sub-compartments (anterior, central, and posterior).
  
  
  RESULTS
  T1rho measurements in the meniscus showed excellent reproducibility (coefficient of variation (CV)<5%). Significantly elevated T1rho values were found in the LM in patients compared with controls (P<0.01). No differences were found in the MM. Significantly higher T1rho values were found at the posterior horn compared with the anterior horn of patients' meniscus (P=0.005). At the posterior sub-compartment of lateral tibia (LT), significantly increased cartilage T1rho values were found in patients compared with controls (P=0.002). A significant correlation (R(2)=0.47, P=0.007) was found between T1rho values of posterior horn of LM and T1rho values of posterior sub-compartment of LT cartilage in patients.
  
  
  CONCLUSIONS
  A strong injury-related relationship was demonstrated between meniscus and cartilage biochemical changes. T1rho mapping techniques provide tools to quantitatively evaluate meniscus and cartilage matrix in patients with ACL injuries.
authors.affiliation: Musculo-skeletal Quantitative Imaging Research (MQIR), Department of Radiology, University of California, San Francisco (UCSF), San Francisco, CA 94107, USA. radu.bolbos@radiology.ucsf.edu
authors.forename: R I
authors.initials: RI
authors.lastname: Bolbos
authors.forename: T M
authors.initials: TM
authors.lastname: Link
authors.forename: C Benjamin
authors.initials: CB
authors.lastname: Ma
authors.forename: S
authors.initials: S
authors.lastname: Majumdar
authors.forename: X
authors.initials: X
authors.lastname: Li
mesh_terms: D000328:Adult; D000070598:Anterior Cruciate Ligament Injuries; D002358:Cartilage, Articular / Q000473:pathology*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D007718:Knee Injuries / Q000473:pathology*; D007719:Knee Joint / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008592:Menisci, Tibial / Q000473:pathology*; D008875:Middle Aged; D015203:Reproducibility of Results; D012189:Retrospective Studies; D055815:Young Adult