title: Focused Dual-energy CT Maintains Diagnostic and Compositional Accuracy for Urolithiasis Using Ultralow-dose Noncontrast CT.
abstract: OBJECTIVE
  To evaluate the diagnostic accuracy of a new energy and radiation dose-reduced protocol for noncontrast computed tomography (NCCT) with dual-energy CT (DECT) analysis and its potential for the compositional analysis of uric acid (UA)- or non-uric acid (N-UA)-containing calculi.
  
  
  METHODS
  A retrospective evaluation was carried out in 61 patients who underwent dose-reduced DECT (tube A: 140 kV/55 mAs; tube B: 80 kV/303 mAs) with a tube current 38.8% lower than that set by the manufacturer. A protocol combining low-dose CT and targeted DE scans was used. Urinary stones were detected and classified as UA- or N-UA-containing or mixed based on DE software results. The accuracy of the compositional analysis was controlled by correlation with conventional infrared-based analysis.
  
  
  RESULTS
  The compositional stone differentiation was correct in 58 of 61 (95.1%) patients. The sensitivity of detecting pure UA-containing and pure N-UA-containing stones was 100%. The specificity of detecting UA- and pure N-UA-containing stones was 100% and 78.57%, respectively, as 3 of 7 mixed urinary stones (small fragments <4 mm) were classified as N-UA calculi. The total radiation dose in patients with body mass index <25 and >25 kg/m(2) was 1.2 and 2.5 mSv, respectively.
  
  
  CONCLUSIONS
  Lowering the DECT tube current by up to 38% of the manufacturer's recommendations allows a reduced radiation dose without impairing detection accuracy and stone compositional analysis. Compared with previous studies, this protocol might significantly decrease patient radiation exposure without affecting the quality of results.
authors.affiliation: Department of Urology, University Medical Center, Freiburg, Germany. Electronic address: konrad.wilhelm@uniklinik-freiburg.de.
authors.forename: Konrad
authors.initials: K
authors.lastname: Wilhelm
authors.affiliation: Department of Urology, University Medical Center, Freiburg, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Schoenthaler
authors.affiliation: Department of Urology, University Medical Center, Freiburg, Germany.
authors.forename: Simon
authors.initials: S
authors.lastname: Hein
authors.affiliation: Department of Urology, University Medical Center, Freiburg, Germany.
authors.forename: Fabian
authors.initials: F
authors.lastname: Adams
authors.affiliation: Department of Urology, University Medical Center, Freiburg, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Schlager
authors.affiliation: Department of Urology, Medical University of Vienna, Wien, Austria.
authors.forename: Franklin Emmanuel
authors.initials: FE
authors.lastname: Kuehhas
authors.affiliation: Department of Urology, Medical University of Vienna, Wien, Austria.
authors.forename: Sabina
authors.initials: S
authors.lastname: Sevcenco
authors.affiliation: Department of Radiology, University Medical Center, Freiburg, Germany.
authors.forename: Gregor
authors.initials: G
authors.lastname: Pache
authors.affiliation: Department of Radiology, University Medical Center, Freiburg, Germany.
authors.forename: Mathias
authors.initials: M
authors.lastname: Langer
authors.affiliation: Department of Radiology, University Medical Center, Freiburg, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Bulla
authors.affiliation: Department of Urology, University Medical Center, Freiburg, Germany.
authors.forename: Arkadiusz
authors.initials: A
authors.lastname: Miernik
mesh_terms: D000328:Adult; D000368:Aged; D015992:Body Mass Index; D005260:Female; D006801:Humans; D007669:Kidney Calculi / Q000737:chemistry* / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011829:Radiation Dosage; D015900:Radiography, Dual-Energy Scanned Projection; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013055:Spectrophotometry, Infrared; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014514:Ureteral Calculi / Q000737:chemistry* / Q000000981:diagnostic imaging*; D014527:Uric Acid / Q000032:analysis
chemical_list: D014527:Uric Acid