title: Dual-energy CT for the diagnosis of gout: an accuracy and diagnostic yield study.
abstract: OBJECTIVE
  To assess the accuracy of dual-energy CT (DECT) for diagnosing gout, and to explore whether it can have any impact on clinical decision making beyond the established diagnostic approach using polarising microscopy of synovial fluid (diagnostic yield).
  
  
  METHODS
  Diagnostic single-centre study of 40 patients with active gout, and 41 individuals with other types of joint disease. Sensitivity and specificity of DECT for diagnosing gout was calculated against a combined reference standard (polarising and electron microscopy of synovial fluid). To explore the diagnostic yield of DECT scanning, a third cohort was assembled consisting of patients with inflammatory arthritis and risk factors for gout who had negative synovial fluid polarising microscopy results. Among these patients, the proportion of subjects with DECT findings indicating a diagnosis of gout was assessed.
  
  
  RESULTS
  The sensitivity and specificity of DECT for diagnosing gout was 0.90 (95% CI 0.76 to 0.97) and 0.83 (95% CI 0.68 to 0.93), respectively. All false negative patients were observed among patients with acute, recent-onset gout. All false positive patients had advanced knee osteoarthritis. DECT in the diagnostic yield cohort revealed evidence of uric acid deposition in 14 out of 30 patients (46.7%).
  
  
  CONCLUSIONS
  DECT provides good diagnostic accuracy for detection of monosodium urate (MSU) deposits in patients with gout. However, sensitivity is lower in patients with recent-onset disease. DECT has a significant impact on clinical decision making when gout is suspected, but polarising microscopy of synovial fluid fails to demonstrate the presence of MSU crystals.
authors.affiliation: Division of Rheumatology, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: Tim
authors.initials: T
authors.lastname: Bongartz
authors.affiliation: Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: Katrina N
authors.initials: KN
authors.lastname: Glazebrook
authors.affiliation: Department of Orthopedic Surgery, Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Kavros
authors.affiliation: Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: Naveen S
authors.initials: NS
authors.lastname: Murthy
authors.affiliation: Department of Family Medicine, Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Merry
authors.affiliation: Department of Family Medicine, Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: Walter B
authors.initials: WB
authors.lastname: Franz
authors.affiliation: Division of Rheumatology, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: Clement J
authors.initials: CJ
authors.lastname: Michet
authors.affiliation: Division of Rheumatology, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: Barath M Akkara
authors.initials: BM
authors.lastname: Veetil
authors.affiliation: Division of Rheumatology, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: John M
authors.initials: JM
authors.lastname: Davis
authors.affiliation: Division of Rheumatology, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Mason
authors.affiliation: Division of Rheumatology, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Warrington
authors.affiliation: Division of Rheumatology, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: Steven R
authors.initials: SR
authors.lastname: Ytterberg
authors.affiliation: Division of Rheumatology, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: Eric L
authors.initials: EL
authors.lastname: Matteson
authors.affiliation: Division of Biomedical Statistics and Informatics, Department of Health Sciences Research, Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: Cynthia S
authors.initials: CS
authors.lastname: Crowson
authors.affiliation: Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: Shuai
authors.initials: S
authors.lastname: Leng
authors.affiliation: Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: Cynthia H
authors.initials: CH
authors.lastname: McCollough
mesh_terms: D015502:Absorptiometry, Photon; D000328:Adult; D000368:Aged; D001168:Arthritis / Q000175:diagnosis / Q000000981:diagnostic imaging*; D016022:Case-Control Studies; D015331:Cohort Studies; D004551:Elbow Joint / Q000000981:diagnostic imaging; D005260:Female; D033023:Foot Joints / Q000000981:diagnostic imaging; D006073:Gout / Q000175:diagnosis / Q000000981:diagnostic imaging*; D050823:Hand Joints / Q000000981:diagnostic imaging; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging; D008297:Male; D008854:Microscopy, Electron; D008859:Microscopy, Polarization; D008875:Middle Aged; D012680:Sensitivity and Specificity; D013582:Synovial Fluid; D014057:Tomography, X-Ray Computed; D014527:Uric Acid
chemical_list: D014527:Uric Acid
keywords: Dual energy CT scanning; Gout; accuracy