title: Dual energy computed tomography in tophaceous gout.
abstract: OBJECTIVE
  To evaluate the potential utility of a dual energy CT (DECT) scan in assessing urate deposits among patients with tophaceous gout, and obtain computerised quantification of tophus volume in peripheral joints.
  
  
  METHODS
  20 consecutive patients with tophaceous gout and 10 control patients with other arthritic conditions were included. DECT scans were performed using a renal stone colour-coding protocol that specifically assessed the chemical composition of the material (ie, urate coloured in red, calcium coloured in blue). An automated volumetric assessment of DECT was used to measure the volume of urate deposits in all peripheral joint areas.
  
  
  RESULTS
  All 20 patients with gout showed red colour-coded urate deposits on their DECT scans, whereas none of 10 controls showed urate deposits. DECT scans revealed a total of 440 areas of urate deposition in 20 patients, whereas physical examination showed 111 areas of urate deposition (mean 22 vs 6 per patient, respectively, p<0.001). Total urate volume in a given patient ranged from 0.63 cm(3) to 249.13 cm(3), with a mean of 40.20 cm(3).
  
  
  CONCLUSIONS
  DECT scans can produce obvious colour displays for urate deposits and help to identify subclinical tophus deposits. Furthermore, tophus volume can be measured by DECT scans through an automated volume estimation procedure.
authors.affiliation: Division of Rheumatology, Vancouver General Hospital, University of British Columbia, Vancouver, Canada. hchoi@arthritisresearch.ca
authors.forename: H K
authors.initials: HK
authors.lastname: Choi
authors.forename: A M
authors.initials: AM
authors.lastname: Al-Arfaj
authors.forename: A
authors.initials: A
authors.lastname: Eftekhari
authors.forename: P L
authors.initials: PL
authors.lastname: Munk
authors.forename: K
authors.initials: K
authors.lastname: Shojania
authors.forename: G
authors.initials: G
authors.lastname: Reid
authors.forename: S
authors.initials: S
authors.lastname: Nicolaou
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D003116:Color; D005260:Female; D006073:Gout / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D014018:Tissue Distribution; D014057:Tomography, X-Ray Computed / Q000379:methods; D014527:Uric Acid / Q000032:analysis
chemical_list: D014527:Uric Acid