title: Diagnostic efficiency of split-bolus dual-energy computed tomography for patients with suspected urinary stones.
abstract: OBJECTIVE
  The objective of this study was to evaluate the efficiency of virtual noncontrast image (VNCI) generated from dual-energy split-bolus computed tomographic urography (DE-SBCTU) for urinary stones detection.
  
  
  METHODS
  Three hundred fifty-six patients underwent true noncontrast image (TNCI) and DE-SBCTU. Two radiologists evaluated opacification scores of DE-SBCTU as well as iodine subtractions and image noise on VNCI. Diagnostic performance of the VNCI was evaluated using TNCI as a reference standard, according to diameter and image quality. The results were compared between patient groups with body mass index of less than 25 and 25 kg/m2 or greater.
  
  
  RESULTS
  Agreements for opacification, iodine subtraction, and image noise between the radiologists were excellent, and there were no significant difference in the 2 patients groups. A total of 499 stones were detected on VNCI, with a sensitivity and diagnostic accuracy of 95.1% (468/492) and 92.9% (499/537). Mean (SD) diameter was significantly smaller on VNCI (3.6 [2.3] mm) than on TNCI (4.4 [2.0] mm) (P = 0.01). The stone diameter with false interpretation was less than 4 mm in 48 of 51 patients. The diameter and image quality on VNCI had no significant difference between the 2 patients groups.
  
  
  CONCLUSIONS
  Virtual noncontrast image displays high accuracy for detecting urinary stones, regardless of body mass index.
authors.affiliation: From the *Department of Radiology, Dongsan Hospital, Keimyung University; †Department of Radiology, Kyungpook National University Hospital; and ‡Department of Radiology, Yeungnam University Hospital, Daegu, South Korea.
authors.forename: Yu Jin
authors.initials: YJ
authors.lastname: Yeo
authors.forename: See Hyung
authors.initials: SH
authors.lastname: Kim
authors.forename: Mi Jeong
authors.initials: MJ
authors.lastname: Kim
authors.forename: Young Hwan
authors.initials: YH
authors.lastname: Kim
authors.forename: Seung Hyun
authors.initials: SH
authors.lastname: Cho
authors.forename: Eun Joo
authors.initials: EJ
authors.lastname: Lee
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011856:Radiographic Image Enhancement / Q000379:methods*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015900:Radiography, Dual-Energy Scanned Projection / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014545:Urinary Calculi / Q000000981:diagnostic imaging*; D014584:User-Computer Interface