Characteristic magnetic resonance imaging entheseal changes of knee synovitis in spondylarthropathy

Arthritis Rheum. 1998 Apr;41(4):694-700. doi: 10.1002/1529-0131(199804)41:4<694::AID-ART17>3.0.CO;2-#.


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).

Conclusion: 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.

MeSH terms

  • Adult
  • Bone Marrow Diseases / diagnostic imaging
  • Bursa, Synovial / abnormalities
  • Bursa, Synovial / diagnostic imaging
  • Connective Tissue / abnormalities
  • Connective Tissue / diagnostic imaging
  • Edema / diagnostic imaging
  • Female
  • Humans
  • Knee Joint / diagnostic imaging*
  • Knee Joint / pathology
  • Magnetic Resonance Imaging*
  • Male
  • Middle Aged
  • Radionuclide Imaging
  • Spondylitis, Ankylosing / complications*
  • Synovitis / complications
  • Synovitis / diagnostic imaging*