title: Characteristic magnetic resonance imaging entheseal changes of knee synovitis in spondylarthropathy.
abstract: OBJECTIVE
  To use magnetic resonance imaging (MRI) in patients with rheumatoid arthritis (RA) and spondylarthropathy (SpA) to determine if the primary site of abnormality differs.
  
  
  METHODS
  Twenty patients with recent-onset knee effusion (10 with SpA and 10 with RA) were evaluated using fat-suppressed MRI. Knee joint effusion and synovitis were confirmed using ultrasonography. MRI scans were independently scored by 2 observers who were blinded to the patient's diagnosis.
  
  
  RESULTS
  All 10 of the SpA patients, but only 4 of the 10 RA patients, had focal peri-entheseal high signal (compatible with fluid or edema) outside the joint (P = 0.01). Six of the SpA patients had bone marrow edema that was maximal at entheseal insertions; in 4 cases this was multifocal. No RA patients showed such an abnormality (P = 0.01).
  
  
  CONCLUSIONS
  Prominent entheseal abnormalities on MRI are a consistent feature of new-onset synovitis in SpA, but are a minor feature of RA. This finding has important implications for the diagnosis, classification, and mechanisms of synovitis in patients with SpA.
authors.affiliation: University of Leeds, UK.
authors.forename: D
authors.initials: D
authors.lastname: McGonagle
authors.forename: W
authors.initials: W
authors.lastname: Gibbon
authors.forename: P
authors.initials: P
authors.lastname: O'Connor
authors.forename: M
authors.initials: M
authors.lastname: Green
authors.forename: C
authors.initials: C
authors.lastname: Pease
authors.forename: P
authors.initials: P
authors.lastname: Emery
mesh_terms: D000328:Adult; D001855:Bone Marrow Diseases / Q000000981:diagnostic imaging; D002061:Bursa, Synovial / Q000002:abnormalities / Q000000981:diagnostic imaging; D003238:Connective Tissue / Q000002:abnormalities / Q000000981:diagnostic imaging; D004487:Edema / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging* / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011877:Radionuclide Imaging; D013167:Spondylitis, Ankylosing / Q000150:complications*; D013585:Synovitis / Q000150:complications / Q000000981:diagnostic imaging*