title: (18)F-FDG PET imaging of rheumatoid knee synovitis correlates with dynamic magnetic resonance and sonographic assessments as well as with the serum level of metalloproteinase-3.
abstract: OBJECTIVE
  The aim of this study was to assess rheumatoid arthritis (RA) synovitis with positron emission tomography (PET) and( 18)F-fluorodeoxyglucose ((18)F-FDG) in comparison with dynamic magnetic resonance imaging (MRI) and ultrasonography (US).
  
  
  METHODS
  Sixteen knees in 16 patients with active RA were assessed with PET, MRI and US at baseline and 4 weeks after initiation of anti-TNF-alpha treatment. All studies were performed within 4 days. Visual and semi-quantitative (standardised uptake value, SUV) analyses of the synovial uptake of FDG were performed. The dynamic enhancement rate and the static enhancement were measured after i.v. gadolinium injection and the synovial thickness was measured in the medial, lateral patellar and suprapatellar recesses by US. Serum levels of C-reactive protein (CRP) and metalloproteinase-3 (MMP-3) were also measured.
  
  
  RESULTS
  PET was positive in 69% of knees while MRI and US were positive in 69% and 75%. Positivity on one imaging technique was strongly associated with positivity on the other two. PET-positive knees exhibited significantly higher SUVs, higher MRI parameters and greater synovial thickness compared with PET-negative knees, whereas serum CRP and MMP-3 levels were not significantly different. SUVs were significantly correlated with all MRI parameters, with synovial thickness and with serum CRP and MMP-3 levels at baseline. Changes in SUVs after 4 weeks were also correlated with changes in MRI parameters and in serum CRP and MMP-3 levels, but not with changes in synovial thickness.
  
  
  CONCLUSIONS
  (18)F-FDG PET is a unique imaging technique for assessing the metabolic activity of synovitis. The PET findings are correlated with MRI and US assessments of the pannus in RA, as well as with the classical serum parameter of inflammation, CRP, and the synovium-derived parameter, serum MMP-3. Further studies are warranted to establish the place of metabolic imaging of synovitis in RA.
authors.affiliation: Division of Nuclear Medicine, Center for Cellular and Molecular Therapy, University Hospital of Liège, Liège, Belgium.
authors.forename: Catherine
authors.initials: C
authors.lastname: Beckers
authors.forename: Xavier
authors.initials: X
authors.lastname: Jeukens
authors.forename: Clio
authors.initials: C
authors.lastname: Ribbens
authors.forename: Béatrice
authors.initials: B
authors.lastname: André
authors.forename: Stefaan
authors.initials: S
authors.lastname: Marcelis
authors.forename: Philippe
authors.initials: P
authors.lastname: Leclercq
authors.forename: Marie-Joëlle
authors.initials: MJ
authors.lastname: Kaiser
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Foidart
authors.forename: Roland
authors.initials: R
authors.lastname: Hustinx
authors.forename: Michel G
authors.initials: MG
authors.lastname: Malaise
mesh_terms: D000328:Adult; D001172:Arthritis, Rheumatoid / Q000097:blood / Q000000981:diagnostic imaging* / Q000473:pathology; D019788:Fluorodeoxyglucose F18; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology; D008279:Magnetic Resonance Imaging; D019278:Matrix Metalloproteinase 3 / Q000097:blood*; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013223:Statistics as Topic; D013585:Synovitis / Q000097:blood / Q000000981:diagnostic imaging* / Q000473:pathology; D014463:Ultrasonography
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D019278:Matrix Metalloproteinase 3