title: Dual energy computed tomography: a novel technique for diagnosis of gout.
abstract: OBJECTIVE
  To evaluate the sensitivity and specificity of dual energy computed tomography (DECT) for diagnosing gout compared with a composite gold standard (CGS) comprising joint aspiration and/or American College of Rheumatology clinico-radiographic criteria.
  
  
  METHODS
  Ninety patients of suspected gout underwent radiography and DECT of bilateral feet and knees. Radiographs and non-contrast CT (NCCT) were assessed for morphological characteristics, following which DECT was used to identify urate deposits.
  
  
  RESULTS
  With CGS as a reference (n = 90), sensitivity of radiographs was 15% (95% confidence interval [CI]: 6-27%) while specificity was 100% (95% CI: 90-100%). Sensitivity of NCCT was 26% (95% CI: 15-40%) while specificity was 97% (95% CI: 85-99%). Sensitivity of DECT was 82% (95% CI: 68-90%) while specificity was 89% (95% CI: 73-96%). Fifty-five patients underwent joint aspiration. Sensitivity and specificity of radiographs and NCCT with aspiration as a reference (n = 55) were not much different from that of CGS. However, DECT showed a higher sensitivity of 100% (95% CI: 86-100%) and a lower specificity of 48% (95%CI: 28-68%) with aspiration alone.
  
  
  CONCLUSIONS
  Dual energy computed tomography had higher sensitivity compared to conventional imaging with CGS as a reference; however, its specificity dropped with aspiration as a reference. It may be a useful adjunct for the diagnosis of gout, especially in the acute and inter-critical stage.
authors.affiliation: Departments of Radiodiagnosis, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Zohra
authors.initials: Z
authors.lastname: Ahmad
authors.affiliation: Departments of Radiodiagnosis, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Arun Kumar
authors.initials: AK
authors.lastname: Gupta
authors.affiliation: Departments of Radiodiagnosis, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Raju
authors.initials: R
authors.lastname: Sharma
authors.affiliation: Departments of Radiodiagnosis, All India Institute of Medical Sciences, New Delhi, India. ashubhalla1@yahoo.com.
authors.forename: Ashu Seith
authors.initials: AS
authors.lastname: Bhalla
authors.affiliation: Departments of Medicine and Rheumatology, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Uma
authors.initials: U
authors.lastname: Kumar
authors.affiliation: Departments of and Biostatistics, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: V
authors.initials: V
authors.lastname: Sreenivas
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000032:analysis / Q000097:blood; D003460:Crystallization; D005260:Female; D033023:Foot Joints / Q000737:chemistry / Q000000981:diagnostic imaging*; D006073:Gout / Q000097:blood / Q000000981:diagnostic imaging*; D006801:Humans; D007719:Knee Joint / Q000737:chemistry / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D013396:Suction; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014527:Uric Acid / Q000032:analysis* / Q000097:blood; D055815:Young Adult
chemical_list: D015415:Biomarkers; D014527:Uric Acid
keywords: arthritis; dual energy computed tomography; gout; tophi