title: The association between histological, macroscopic and magnetic resonance imaging assessed synovitis in end-stage knee osteoarthritis: a cross-sectional study.
abstract: To investigate the association between magnetic resonance imaging (MRI), macroscopic and histological assessments of synovitis in end-stage knee osteoarthritis (KOA).
  
  
  
  Synovitis of end-stage osteoarthritic knees was assessed using non-contrast-enhanced (CE), contrast-enhanced magnetic resonance imaging (CE-MRI) and dynamic contrast-enhanced (DCE)-MRI prior to (TKR) and correlated with microscopic and macroscopic assessments of synovitis obtained intraoperatively. Multiple bivariate correlations were used with a pre-specified threshold of 0.70 for significance. Also, multiple regression analyses with different subsets of MRI-variables as explanatory variables and the histology score as outcome variable were performed with the intention to find MRI-variables that best explain the variance in histological synovitis (i.e., highest R2). A stepped approach was taken starting with basic characteristics and non-CE MRI-variables (model 1), after which CE-MRI-variables were added (model 2) with the final model also including DCE-MRI-variables (model 3).
  
  
  
  39 patients (56.4% women, mean age 68 years, Kellgren-Lawrence (KL) grade 4) had complete MRI and histological data. Only the DCE-MRI variable MExNvoxel (surrogate of the volume and degree of synovitis) and the macroscopic score showed correlations above the pre-specified threshold for acceptance with histological inflammation. The maximum R2-value obtained in Model 1 was R2= 0.39. In Model 2, where the CE-MRI-variables were added, the highest R2= 0.52. In Model 3, a four-variable model consisting of the gender, one CE-MRI and two DCE-MRI-variables yielded a R2= 0.71.
  
  
  
  DCE-MRI is correlated with histological synovitis in end-stage KOA and the combination of CE and DCE-MRI may be a useful, non-invasive tool in characterising synovitis in KOA.
authors.affiliation: The Parker Institute, Copenhagen University Hospital Bispebjerg-Frederiksberg, Denmark; Department of Radiology, Copenhagen University Hospital Bispebjerg-Frederiksberg, Denmark; Department of Radiology, Zealand University Hospital Holbaek, Denmark. Electronic address: riis.robert@gmail.com.
authors.forename: R G C
authors.initials: RG
authors.lastname: Riis
authors.affiliation: The Parker Institute, Copenhagen University Hospital Bispebjerg-Frederiksberg, Denmark. Electronic address: rindelgudbergsen@gmail.com.
authors.forename: H
authors.initials: H
authors.lastname: Gudbergsen
authors.affiliation: Orthopaedic Surgery Research Unit, Aalborg University Hospital, Aalborg, Denmark. Electronic address: ohs@rn.dk.
authors.forename: O
authors.initials: O
authors.lastname: Simonsen
authors.affiliation: The Parker Institute, Copenhagen University Hospital Bispebjerg-Frederiksberg, Denmark; Department of Physical and Occupational Therapy, Copenhagen University Hospital Bispebjerg-Frederiksberg, Denmark. Electronic address: marius.henriksen@regionh.dk.
authors.forename: M
authors.initials: M
authors.lastname: Henriksen
authors.affiliation: Department of Pathology, Aalborg University Hospital, Aalborg, Denmark. Electronic address: nma@rn.dk.
authors.forename: N
authors.initials: N
authors.lastname: Al-Mashkur
authors.affiliation: Department of Pathology, Aalborg University Hospital, Aalborg, Denmark. Electronic address: mikkel.eld@rn.dk.
authors.forename: M
authors.initials: M
authors.lastname: Eld
authors.affiliation: Centre for Sensory-Motor Interaction, Aalborg University, Aalborg, Denmark. Electronic address: kkp@hst.au.dk.
authors.forename: K K
authors.initials: KK
authors.lastname: Petersen
authors.affiliation: Image Analysis Ltd., London, United Kingdom. Electronic address: olga@imageanalysis.org.uk.
authors.forename: O
authors.initials: O
authors.lastname: Kubassova
authors.affiliation: Nordic Bioscience, Herlev, Denmark. Electronic address: acbj@nordicbioscience.com.
authors.forename: A C
authors.initials: AC
authors.lastname: Bay Jensen
authors.affiliation: Department of Radiology, Copenhagen University Hospital Bispebjerg-Frederiksberg, Denmark. Electronic address: janus.nybing.damm@regionh.dk.
authors.forename: J
authors.initials: J
authors.lastname: Damm
authors.affiliation: The Parker Institute, Copenhagen University Hospital Bispebjerg-Frederiksberg, Denmark. Electronic address: henning.bliddal@regionh.dk.
authors.forename: H
authors.initials: H
authors.lastname: Bliddal
authors.affiliation: Centre for Sensory-Motor Interaction, Aalborg University, Aalborg, Denmark. Electronic address: lan@hst.aau.dk.
authors.forename: L
authors.initials: L
authors.lastname: Arendt-Nielsen
authors.affiliation: The Parker Institute, Copenhagen University Hospital Bispebjerg-Frederiksberg, Denmark; Department of Radiology, Copenhagen University Hospital Bispebjerg-Frederiksberg, Denmark. Electronic address: mikael.boesen@gmail.com.
authors.forename: M
authors.initials: M
authors.lastname: Boesen
mesh_terms: D000368:Aged; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging / Q000473:pathology*; D013585:Synovitis / Q000000981:diagnostic imaging / Q000473:pathology*
keywords: Dynamic contrast-enhanced magnetic resonance imaging; Histology; Knee osteoarthritis; Magnetic resonance imaging; Synovitis