title: Single-phase dual-energy CT urography in the evaluation of haematuria.
abstract: OBJECTIVE
  To assess the value of a single-phase dual-energy computed tomography (DECT) urography protocol with synchronous nephrographic-excretory phase enhancement and to calculate the potential dose reduction by omitting the unenhanced scan.
  
  
  METHODS
  Eighty-four patients referred for haematuria underwent CT urography using a protocol that included single-energy unenhanced and dual-energy contrast-enhanced with synchronous nephrographic-excretory phase scans. DECT-based images [virtual unenhanced (VUE), weighted average, and colour-coded iodine overlay] were reconstructed. Opacification degree by contrast media of the upper urinary tract, and image quality of virtual unenhanced images were independently evaluated using a four-point scale. The diagnostic accuracy in detecting urothelial tumours on DECT-based images was determined. The dose of a theoretical dual-phase single-energy protocol was obtained by multiplying the effective dose of the unenhanced single-energy acquisition by two. Radiation dose saving by omitting the unenhanced scan was calculated.
  
  
  RESULTS
  The degree of opacification was scored as optimal or good in 86.9% of cases (k = 0.72); VUE image quality was excellent or good in 83.3% of cases (k = 0.82). Sensitivity, specificity, positive predictive value, and negative predictive value for urothelial tumours detection were 85.7, 98.6, 92.3, and 97.1%. Omission of the unenhanced scan led to a mean dose reduction of 42.7 ± 5%.
  
  
  CONCLUSIONS
  Single-phase DECT urography with synchronous nephrographic-excretory phase enhancement represents an accurate "all-in-one'' approach with a radiation dose saving up to 45% compared with a standard dual-phase protocol.
authors.affiliation: Department of Radiological Sciences, Policlinico G. Martino, University of Messina, Messina, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Ascenti
authors.forename: A
authors.initials: A
authors.lastname: Mileto
authors.forename: M
authors.initials: M
authors.lastname: Gaeta
authors.forename: A
authors.initials: A
authors.lastname: Blandino
authors.forename: S
authors.initials: S
authors.lastname: Mazziotti
authors.forename: E
authors.initials: E
authors.lastname: Scribano
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D003287:Contrast Media; D005069:Evaluation Studies as Topic; D005260:Female; D006417:Hematuria / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011829:Radiation Dosage; D011856:Radiographic Image Enhancement / Q000379:methods*; D015900:Radiography, Dual-Energy Scanned Projection / Q000379:methods*; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods; D014567:Urography / Q000379:methods*
chemical_list: D003287:Contrast Media