title: Bone erosions and bone marrow edema as defined by magnetic resonance imaging reflect true bone marrow inflammation in rheumatoid arthritis.
abstract: OBJECTIVE
  To investigate the pathologic nature of features termed "bone erosion" and "bone marrow edema" (also called "osteitis) on magnetic resonance imaging (MRI) scans of joints affected by rheumatoid arthritis (RA).
  
  
  METHODS
  RA patients scheduled for joint replacement surgery (metacarpophalangeal or proximal interphalangeal joints) underwent MRI on the day before surgery. The presence and localization of bone erosions and bone marrow edema as evidenced by MRI (MRI bone erosions and MRI bone marrow edema) were documented in each joint (n=12 joints). After surgery, sequential sections from throughout the whole joint were analyzed histologically for bone marrow changes, and these results were correlated with the MRI findings.
  
  
  RESULTS
  MRI bone erosion was recorded based on bone marrow inflammation adjacent to a site of cortical bone penetration. Inflammation was recorded based on either invading synovial tissue (pannus), formation of lymphocytic aggregates, or increased vascularity. Fat-rich bone marrow was replaced by inflammatory tissue, increasing water content, which appears as bright signal enhancement on STIR MRI sequences. MRI bone marrow edema was recorded based on the finding of inflammatory infiltrates, which were less dense than those of MRI bone erosions and localized more centrally in the joint. These lesions were either isolated or found in contact with MRI bone erosions.
  
  
  CONCLUSIONS
  MRI bone erosions and MRI bone marrow edema are due to the formation of inflammatory infiltrates in the bone marrow of patients with RA. This emphasizes the value of MRI in sensitively detecting inflammatory tissue in the bone marrow and demonstrates that the inflammatory process extends to the bone marrow cavity, which is an additional target structure for antiinflammatory therapy.
authors: Medical University of Vienna, Vienna, Austria.
authors: Esther
authors: E
authors: Jimenez-Boj
authors: Iris
authors: I
authors: Nöbauer-Huhmann
authors: Beatrice
authors: B
authors: Hanslik-Schnabel
authors: Ronald
authors: R
authors: Dorotka
authors: Axel-Hugo
authors: AH
authors: Wanivenhaus
authors: Franz
authors: F
authors: Kainberger
authors: Siegfried
authors: S
authors: Trattnig
authors: Roland
authors: R
authors: Axmann
authors: Wayne
authors: W
authors: Tsuji
authors: Sonja
authors: S
authors: Hermann
authors: Josef
authors: J
authors: Smolen
authors: Georg
authors: G
authors: Schett
mesh_terms: D000328:Adult; D001172:Arthritis, Rheumatoid / Q000473:pathology* / Q000601:surgery; D050806:Arthroplasty, Replacement, Finger; D001853:Bone Marrow / Q000473:pathology*; D004487:Edema / Q000473:pathology*; D005260:Female; D005384:Finger Joint / Q000473:pathology* / Q000601:surgery; D006801:Humans; D008279:Magnetic Resonance Imaging; D008662:Metacarpophalangeal Joint / Q000473:pathology* / Q000601:surgery; D008875:Middle Aged; D010000:Osteitis / Q000473:pathology* / Q000601:surgery