title: Comparison of ultrasound and magnetic resonance urography for evaluation of contralateral kidney in patients with multicystic dysplastic kidney disease.
abstract: OBJECTIVE
  The contralateral kidney is abnormal in up to 25% of patients with multicystic dysplastic kidney. Traditionally, anatomical and functional evaluation of the contralateral kidney has been performed with ultrasound and dimercapto-succinic acid renal scintigraphy, as indicated. Recently magnetic resonance urography has been used to evaluate renal anatomy and function in other urological abnormalities. We compared the results of magnetic resonance urography and ultrasound for evaluating the contralateral kidney in patients with multicystic dysplastic kidney and we describe the range of findings detected.
  
  
  METHODS
  Patients with multicystic dysplastic kidney who underwent magnetic resonance urography were identified. Anatomical findings on magnetic resonance urography were analyzed and compared to those on renal ultrasound. Additional functional information derived from magnetic resonance urography was also recorded.
  
  
  RESULTS
  We retrospectively identified 58 patients with a unilateral multicystic dysplastic kidney who had undergone magnetic resonance urography, of whom 54 also underwent ultrasound. Of the patients 19 (32.8%) had a contralateral abnormality. A discrepancy between magnetic resonance urography and ultrasound was seen in 9 patients (16.7%). Of these patients only 1 had a completely normal contralateral kidney by ultrasound on retrospective review. The incidence and range of parenchymal abnormalities was wider than previously reported.
  
  
  CONCLUSIONS
  Contralateral abnormalities in children with multicystic dysplastic kidney are common and more definitively evaluated with magnetic resonance urography vs ultrasound. Renal ultrasound remains the most appropriate modality for the initial evaluation of children with multicystic dysplastic kidney, and magnetic resonance urography is recommended when a functional study is required either to confirm the diagnosis of multicystic dysplastic kidney or to evaluate suspected abnormalities of the contralateral kidney.
authors.affiliation: Emory University School of Medicine and Children's Healthcare of Atlanta, Atlanta, Georgia 30342, USA. jonkalisvaart@gmail.com
authors.forename: Jonathan
authors.initials: J
authors.lastname: Kalisvaart
authors.forename: Yasmin
authors.initials: Y
authors.lastname: Bootwala
authors.forename: Husain
authors.initials: H
authors.lastname: Poonawala
authors.forename: James
authors.initials: J
authors.lastname: Elmore
authors.forename: Andrew
authors.initials: A
authors.lastname: Kirsch
authors.forename: Hal
authors.initials: H
authors.lastname: Scherz
authors.forename: Richard
authors.initials: R
authors.lastname: Jones
authors.forename: J Damien
authors.initials: JD
authors.lastname: Grattan-Smith
authors.forename: Edwin
authors.initials: E
authors.lastname: Smith
mesh_terms: D002648:Child; D005260:Female; D006801:Humans; D007668:Kidney / Q000002:abnormalities / Q000000981:diagnostic imaging*; D008279:Magnetic Resonance Imaging; D008297:Male; D021782:Multicystic Dysplastic Kidney / Q000150:complications; D012189:Retrospective Studies; D014463:Ultrasonography; D014567:Urography / Q000379:methods