title: Quantitative assessment of bone marrow edema-like lesion and overlying cartilage in knees with osteoarthritis and anterior cruciate ligament tear using MR imaging and spectroscopic imaging at 3 Tesla.
abstract: OBJECTIVE
  To quantitatively assess bone marrow edema-like lesion (BMEL) and the overlying cartilage in osteoarthritis (OA) or anterior cruciate ligament (ACL)-injured knees using magnetic resonance imaging (MRI) and spectroscopic imaging (MRSI).
  
  
  METHODS
  Eight healthy controls and 30 patients with OA and other injuries who showed BMEL were scanned at 3.0T. A regression model was constructed to automatically calculate the volume of BMEL. Normalized T(1rho) z-scores were calculated within BMEL-overlying cartilage. Three-dimensional (3D) MRSI was acquired in the BMEL and surrounding bone marrow.
  
  
  RESULTS
  The mean T(1rho) z-score was significantly higher in BMEL-overlying cartilage than that in surrounding cartilage in the lateral tibia of patients with ACL tears (P < 0.001). Significantly elevated water and unsaturated lipids, and decreased saturated lipids were observed in BMEL. The volume of elevated water correlated with the volume of BMEL. Water content was significantly higher within BMEL than that outside BMEL. The unsaturation index outside BMEL was significantly higher in patients with ACL tears than that in OA.
  
  
  CONCLUSIONS
  3D MRSI and T(1rho) mapping provide tools to quantitatively evaluate BMEL in OA and knee injury. This may allow us to better understand pathophysiology and evolution of injuries and degenerative conditions of the knee.
authors.affiliation: Musculo-skeletal Quantitative Imaging Research (MQIR), Department of Radiology, University of California, San Francisco (UCSF), San Francisco, California 94107, USA. xiaojuan.li@radiology.ucsf.edu
authors.forename: Xiaojuan
authors.initials: X
authors.lastname: Li
authors.forename: Benjamin C
authors.initials: BC
authors.lastname: Ma
authors.forename: Radu I
authors.initials: RI
authors.lastname: Bolbos
authors.forename: Robert
authors.initials: R
authors.lastname: Stahl
authors.forename: Jesus
authors.initials: J
authors.lastname: Lozano
authors.forename: Jin
authors.initials: J
authors.lastname: Zuo
authors.forename: Katrina
authors.initials: K
authors.lastname: Lin
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Link
authors.forename: Marc
authors.initials: M
authors.lastname: Safran
authors.forename: Sharmila
authors.initials: S
authors.lastname: Majumdar
mesh_terms: D000328:Adult; D000368:Aged; D000070598:Anterior Cruciate Ligament Injuries; D001853:Bone Marrow / Q000473:pathology*; D002358:Cartilage, Articular / Q000473:pathology*; D016022:Case-Control Studies; D004487:Edema / Q000473:pathology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000473:pathology*; D012044:Regression Analysis