title: Genitourinary imaging with noncontrast computerized tomography--are we missing duplex ureters?
abstract: OBJECTIVE
  Noncontrast computerized tomography has replaced excretory urography as the first line diagnostic tool for evaluating nephrolithiasis at many centers. We evaluated the ability of noncontrast computerized tomography to detect ureteral duplication to determine how frequently these anomalies are under diagnosed.
  
  
  METHODS
  Computerized tomography images of 14 patients with known ureteral duplication who had previously undergone noncontrast and contrast enhanced computerized tomography and 5 control patients with normal ureteral anatomy were interpreted by 2 blinded radiologists who specialize in genitourinary imaging.
  
  
  RESULTS
  The sensitivity of axial computerized tomography with contrast material, axial computerized tomography without contrast material and coronal computerized tomography without contrast material was 96%, 59% and 65%, respectively. The negative predictive value of axial computerized tomography with contrast material, axial computerized tomography without contrast material and coronal computerized tomography without contrast material was 95%, 65% and 67%, respectively. The accuracy of axial computerized tomography with contrast medium was significantly higher than that of noncontrast axial or noncontrast coronal computerized tomography (each p <0.01).
  
  
  CONCLUSIONS
  Duplicated ureters, which represent a challenge to the endourologist, are under diagnosed on noncontrast computerized tomography. Urologists and radiologists should be aware of this limitation and contrast studies should be done when anatomical anomalies are suspected.
authors.affiliation: Kidney Stone Center, Department of Urology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA. beisner@partners.org
authors.forename: Brian H
authors.initials: BH
authors.lastname: Eisner
authors.forename: Mehrine
authors.initials: M
authors.lastname: Shaikh
authors.forename: Raul N
authors.initials: RN
authors.lastname: Uppot
authors.forename: Dushyant V
authors.initials: DV
authors.lastname: Sahani
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Dretler
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed; D014513:Ureter / Q000002:abnormalities*; D014515:Ureteral Diseases / Q000151:congenital / Q000000981:diagnostic imaging*