title: Effectiveness of MR urography in the evaluation of kidney which failed to opacify during excretory urography: comparison with ultrasonography.
abstract: OBJECTIVE
  The purpose of this study was to compare the effectiveness of MR urography (MRU) with that of ultrasonography (US) in the evaluation of urinary tract when this failed to opacify during excretory urography (EXU).
  
  
  METHODS
  Twelve urinary tracts in 11 patients were studied. In each case, during EXU, the urinary system failed to opacify within one hour of the injection of contrast media, and US revealed dilatation of the pelvocalyceal system. Patients underwent MRU, using a HASTE sequence with the breath-hold technique; multi-slice acquisition was then performed, and the images were reconstructed using maximal intensity projection. Each set of images was evaluated by three radiologists to determine the presence, level, and cause of urinary tract obstruction.
  
  
  RESULTS
  Obstruction was present in all twelve cases, and in all of these, MRU accurately demonstrated its level. In this respect, however, US was successful in only ten. The cause of obstruction was determined by MRU in eight cases, but by US in only six. In all of these six, MRU also successfully demonstrated the cause.
  
  
  CONCLUSIONS
  MRU is an effective modality for evaluation of the urinary tract when this fails to opacify during EXU, and appears to be superior to US in demonstrating the level and cause of obstruction.
authors.affiliation: Department of Radiology, Seoul National University Hospital, Seoul, Korea.
authors.forename: S I
authors.initials: SI
authors.lastname: Hwang
authors.forename: S H
authors.initials: SH
authors.lastname: Kim
authors.forename: Y J
authors.initials: YJ
authors.lastname: Kim
authors.forename: A Y
authors.initials: AY
authors.lastname: Kim
authors.forename: J Y
authors.initials: JY
authors.lastname: Cho
authors.forename: J W
authors.initials: JW
authors.lastname: Lee
authors.forename: H S
authors.initials: HS
authors.lastname: Kim
authors.forename: K M
authors.initials: KM
authors.lastname: Yeon
mesh_terms: D005260:Female; D006801:Humans; D007668:Kidney / Q000000981:diagnostic imaging / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D013997:Time Factors; D014463:Ultrasonography; D014551:Urinary Tract / Q000000981:diagnostic imaging / Q000473:pathology*; D014567:Urography; D014570:Urologic Diseases / Q000175:diagnosis*