title: Magnetic resonance imaging of subchondral bone marrow lesions in association with osteoarthritis.
abstract: OBJECTIVE
  This nonsystematic literature review provides an overview of magnetic resonance imaging (MRI) of subchondral bone marrow lesions (BMLs) in association with osteoarthritis (OA), with particular attention to the selection of MRI sequences and semiquantitative scoring systems, characteristic morphology, and differential diagnosis. Histologic basis, natural history, and clinical significance are also briefly discussed.
  
  
  METHODS
  PubMed was searched for articles published up to 2011, using the keywords bone marrow lesion, osteoarthritis, magnetic resonance imaging, bone marrow edema, histology, pain, and subchondral.
  
  
  RESULTS
  BMLs in association with OA correspond to fibrosis, necrosis, edema, and bleeding of fatty marrow as well as abnormal trabeculae on histopathology. Lesions may fluctuate in size within a short time and are associated with the progression of articular cartilage loss and fluctuation of pain in knee OA. The characteristic subchondral edema-like signal intensity of BMLs should be assessed using T2-weighted, proton density-weighted, intermediate-weighted fat-suppressed fast spin echo or short tau inversion recovery. Several semiquantitative scoring systems are available to characterize and grade the severity of BMLs. Quantitative approaches have also been introduced. Differential diagnoses of degenerative BMLs include a variety of traumatic or nontraumatic pathologies that may appear similar to OA-related BMLs on MRI.
  
  
  CONCLUSIONS
  Subchondral BMLs are a common imaging feature of OA with clinical significance and typical signal alteration patterns, which can be assessed and graded by semiquantitative scoring systems using sensitive MRI sequences.
authors.affiliation: Department of Radiology, Boston University School of Medicine, Boston, MA, USA.
authors.forename: Li
authors.initials: L
authors.lastname: Xu
authors.forename: Daichi
authors.initials: D
authors.lastname: Hayashi
authors.forename: Frank W
authors.initials: FW
authors.lastname: Roemer
authors.forename: David T
authors.initials: DT
authors.lastname: Felson
authors.forename: Ali
authors.initials: A
authors.lastname: Guermazi
mesh_terms: D001853:Bone Marrow / Q000293:injuries / Q000473:pathology; D001855:Bone Marrow Diseases / Q000453:epidemiology / Q000473:pathology*; D001856:Bone Marrow Examination; D002358:Cartilage, Articular / Q000473:pathology; D015897:Comorbidity; D003288:Contusions / Q000175:diagnosis; D003937:Diagnosis, Differential; D018450:Disease Progression; D004487:Edema / Q000473:pathology; D005355:Fibrosis / Q000473:pathology; D006801:Humans; D007719:Knee Joint / Q000473:pathology / Q000503:physiopathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009336:Necrosis / Q000473:pathology; D020370:Osteoarthritis, Knee / Q000150:complications / Q000175:diagnosis* / Q000453:epidemiology; D010146:Pain / Q000473:pathology; D014947:Wounds and Injuries / Q000175:diagnosis