title: High frequency of capsular knee involvement in polymyalgia rheumatica/giant cell arteritis patients studied by positron emission tomography.
abstract: OBJECTIVE
  Peripheral arthritis has been described in up to 50% of PMR patients, with knee involvement in the majority. This study was designed to evaluate by PET/CT the knees of patients with PMR and GCA and to identify the knee structures involved by inflammation.
  
  
  METHODS
  Twenty-five consecutive patients with PMR (19) or GCA (6) were studied in comparison with 25 age- and sex-matched controls who underwent PET/CT for initial staging of cancer. Clinical features, ESR and CRP were evaluated. Simultaneous FDG-PET and CT imaging from the skull base to the knee was performed after injection of 4.8-5.2 MBq of [(18)F]FDG per kilogram body weight. The knee anatomical structures being evaluated included joints, fibrous capsule, synovial recesses and bursae.
  
  
  RESULTS
  At PET/CT, 21/25 patients (84%) showed bilateral diffuse uptake at the knees. The tracer clearly outlined the contour of the fibrous capsule. In 50 knees, 90% of capsular sites were involved by inflammation in comparison with 23% of intracapsular sites and 4.7% of extracapsular sites (P < 0.0001). No correlation was found between PET/CT results and ESR or CRP. FDG uptake, with a pattern similar to that observed in 96% of PMR/GCA patients, was seen in 20% of controls (P = 0.03).
  
  
  CONCLUSIONS
  Our findings suggest that bilateral capsulitis of the knee is detectable in most PMR/GCA patients if a sensitive imaging technique such as PET/CT is used.
authors.affiliation: Clinica Reumatologica, Dipartimento di Medicina Interna e Specialità Mediche, Viale Benedetto XV, 6, 16132 Genova, Italy. cimmino@unige.it.
authors.forename: Marco A
authors.initials: MA
authors.lastname: Cimmino
authors.forename: Dario
authors.initials: D
authors.lastname: Camellino
authors.forename: Francesco
authors.initials: F
authors.lastname: Paparo
authors.forename: Silvia
authors.initials: S
authors.lastname: Morbelli
authors.forename: Michela
authors.initials: M
authors.lastname: Massollo
authors.forename: Maurizio
authors.initials: M
authors.lastname: Cutolo
authors.forename: Gianmario
authors.initials: G
authors.lastname: Sambuceti
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood; D001799:Blood Sedimentation; D002062:Bursitis / Q000000981:diagnostic imaging; D002097:C-Reactive Protein / Q000378:metabolism; D016022:Case-Control Studies; D005260:Female; D013700:Giant Cell Arteritis / Q000000981:diagnostic imaging*; D006801:Humans; D017746:Joint Capsule / Q000000981:diagnostic imaging*; D007719:Knee Joint / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging / Q000379:methods; D011111:Polymyalgia Rheumatica / Q000000981:diagnostic imaging*; D049268:Positron-Emission Tomography; D014057:Tomography, X-Ray Computed
chemical_list: D015415:Biomarkers; D002097:C-Reactive Protein
keywords: PET; giant cell arteritis; knee; polymyalgia rheumatica