title: Contrast-enhanced magnetic resonance angiography for the detection of crossing renal vessels in children with symptomatic ureteropelvic junction obstruction: comparison with operative findings.
abstract: BACKGROUND
  Crossing renal vessels (CRV) are associated with ureteropelvic junction (UPJ) obstruction, particularly when presentation is beyond the neonatal period. Their presence may influence surgical management.
  
  
  OBJECTIVE
  To evaluate the accuracy of contrast-enhanced magnetic resonance angiography (CE-MRA) in the identification of CRV in children requiring surgical treatment of symptomatic UPJ obstruction, against a gold standard of laparoscopic or open surgical findings.
  
  
  METHODS
  We reviewed CE-MRA studies (3-D T2-weighted turbo spin-echo and multiphase 3-D spoiled gradient echo following intravenous gadolinium administration) of 14 children, age range 6-15 years, performed prior to surgery for suspected CRV-related UPJ obstruction. Consensus reviews of the CE-MRA studies were compared with surgical findings.
  
  
  RESULTS
  CE-MRA demonstrated CRV at the level of the obstruction in nine and no crossing vessels in five children. These were all verified intraoperatively (chi2=14.0; P<0.001). In eight of the nine patients with CRV there was no evidence of intrinsic obstruction at surgery. In the remaining patient there was fibrosis of the upper ureter.
  
  
  CONCLUSIONS
  CE-MRA is an accurate means of identifying CRV in children older than 6 years with symptomatic UPJ obstruction.
authors.affiliation: Department of Radiology, Great Ormond Street Hospital for Children NHS Trust, London, WC1N 3JH, UK.
authors.forename: Alistair D
authors.initials: AD
authors.lastname: Calder
authors.forename: Melanie P
authors.initials: MP
authors.lastname: Hiorns
authors.forename: Aruna
authors.initials: A
authors.lastname: Abhyankar
authors.forename: Imran
authors.initials: I
authors.lastname: Mushtaq
authors.forename: Oystein E
authors.initials: OE
authors.lastname: Olsen
mesh_terms: D000293:Adolescent; D002648:Child; D003287:Contrast Media / Q000008:administration & dosage; D005260:Female; D005355:Fibrosis; D019786:Gadolinium DTPA / Q000008:administration & dosage; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D007275:Injections, Intravenous; D007682:Kidney Pelvis / Q000098:blood supply*; D010535:Laparoscopy; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D015609:Organotechnetium Compounds; D011866:Radioisotope Renography; D019275:Radiopharmaceuticals; D012189:Retrospective Studies; D014513:Ureter / Q000098:blood supply; D014517:Ureteral Obstruction / Q000175:diagnosis* / Q000601:surgery
chemical_list: D003287:Contrast Media; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; D019786:Gadolinium DTPA