title: Peripatellar synovitis: comparison between non-contrast-enhanced and contrast-enhanced MRI and association with pain. The MOST study.
abstract: OBJECTIVE
  To assess the diagnostic performance of signal changes in Hoffa's fat pad (HFP) assessed on non-contrast-enhanced (CE) magnetic resonance imaging (MRI) in detecting synovitis, and the association of pain with signal changes in HFP on non-CE MRI and peripatellar synovial thickness on CE MRI.
  
  
  METHODS
  The Multicenter Osteoarthritis (MOST) Study is an observational study of individuals who have or are at high risk for knee OA. All subjects with available non-CE and CE MRIs were included. Signal changes in HFP were scored from 0 to 3 in two regions using non-CE MRI. Synovial thickness was scored from 0 to 2 on CE MRI in five peripatellar regions. Sensitivity, specificity and accuracy of HFP signal changes were calculated considering synovial thickness on CE MRI as the reference standard. We used logistic regression to assess the associations of HFP changes (non-CE MRI) and synovial thickness (CE MRI) with pain from walking up or down stairs, after adjusting for potential confounders.
  
  
  RESULTS
  A total of 393 subjects were included. Sensitivity of infrapatellar and intercondylar signal changes in HFP was high (71% and 88%), but specificity was low (55% and 30%). No significant associations were found between HFP changes on non-CE MRI and pain. Grade 2 synovial thickness assessed on CE MRI was significantly associated with pain after adjustments for potential confounders.
  
  
  CONCLUSIONS
  Signal changes in HFP detected on non-CE MRI are a sensitive but non-specific surrogate for the assessment of synovitis. CE MRI identifies associations with pain better than non-CE MRI.
authors.affiliation: Department of Radiology, Quantitative Imaging Center, Boston University School of Medicine, Boston, MA, USA. michelcrema@gmail.com
authors.forename: M D
authors.initials: MD
authors.lastname: Crema
authors.forename: D T
authors.initials: DT
authors.lastname: Felson
authors.forename: F W
authors.initials: FW
authors.lastname: Roemer
authors.forename: J
authors.initials: J
authors.lastname: Niu
authors.forename: M D
authors.initials: MD
authors.lastname: Marra
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
authors.forename: J A
authors.initials: JA
authors.lastname: Lynch
authors.forename: G Y
authors.initials: GY
authors.lastname: El-Khoury
authors.forename: C E
authors.initials: CE
authors.lastname: Lewis
authors.forename: A
authors.initials: A
authors.lastname: Guermazi
mesh_terms: D000273:Adipose Tissue / Q000473:pathology; D018771:Arthralgia / Q000209:etiology / Q000473:pathology*; D003287:Contrast Media; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D007719:Knee Joint / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008875:Middle Aged; D010003:Osteoarthritis / Q000150:complications; D010329:Patella / Q000473:pathology; D012680:Sensitivity and Specificity; D013583:Synovial Membrane / Q000473:pathology*; D013585:Synovitis / Q000150:complications / Q000175:diagnosis*
chemical_list: D003287:Contrast Media; C064925:gadodiamide; D019786:Gadolinium DTPA