title: Dynamic gadolinium-enhanced magnetic resonance urography for assessing drainage in dilated pelvicalyceal systems with moderate renal function: preliminary results and comparison with diuresis renography.
abstract: OBJECTIVE
  To evaluate the use of dynamic gadolinium diethylenetriaminepenta-acetic acid (DTPA)-enhanced magnetic resonance urography (Gd-MRU) for assessing kidneys with markedly dilated pelvicalyceal systems and impaired function.
  
  
  METHODS
  Eight children (mean age 30 months, sd 25) were assessed, diagnosed as having gross unilateral hydronephrosis with a mean (sd) anteroposterior renal pelvic diameter of 36 (7) mm and reduced (30-40%) renal function. Dynamic Gd-MRU was performed after the patients were pre-loaded with intravenous fluid and diuretics, and comprised a dynamic T1-weighted sequence after Gd-DTPA (0.1 mmol/kg body weight) was administered, with a time-intensity curve of each kidney produced. Drainage was diagnosed by a clearly declining time-intensity curve and direct visualization of contrast medium within the ureter in several frames. High-grade or complete obstruction was diagnosed when drainage of contrast medium could not be detected. Gd-MRU results were compared with diuresis radionuclide (mercapto-acetyltriglycine, MAG3) renography within the same week. Unobstructive units detected by Gd-MRU were treated conservatively with a close follow-up by ultrasonography and radionuclide studies.
  
  
  RESULTS
  Diuresis MAG3 renography showed drainage in three dilated units and poor washout in five; in contrast, Gd-MRU showed drainage in seven dilated systems (three showed poor washout by MAG3), and obstruction in the remaining case. The unobstructed units detected by MRU under conservative treatment thus showed no further deterioration of renal function or progressive hydronephrosis in the subsequent follow-up (mean 18 months, range 15-23).
  
  
  CONCLUSIONS
  These preliminary results suggest that dynamic Gd-MRU is a useful noninvasive imaging method in distinguishing obstructive from unobstructive dilated systems, particularly in patients with hydronephrosis and reduced renal function.
authors.affiliation: Department of Diagnostic Radiology and Organ Imaging, The Chinese University of Hong Kong, Prince of Wales Hospital, 30-32 Ngan Shing Street, Shatin, Hong Kong SAR, China. winnie@med.cuhk.edu.hk
authors.forename: W C W
authors.initials: WC
authors.lastname: Chu
authors.forename: W W M
authors.initials: WW
authors.lastname: Lam
authors.forename: K W
authors.initials: KW
authors.lastname: Chan
authors.forename: C K
authors.initials: CK
authors.lastname: Yeung
authors.forename: K H
authors.initials: KH
authors.lastname: Lee
authors.forename: J D Y
authors.initials: JD
authors.lastname: Sihoe
mesh_terms: D002648:Child; D002675:Child, Preschool; D003287:Contrast Media; D004108:Dilatation, Pathologic / Q000000981:diagnostic imaging / Q000473:pathology; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D006869:Hydronephrosis / Q000000981:diagnostic imaging* / Q000473:pathology; D007223:Infant; D007682:Kidney Pelvis / Q000000981:diagnostic imaging; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D011866:Radioisotope Renography / Q000379:methods; D014517:Ureteral Obstruction / Q000000981:diagnostic imaging* / Q000473:pathology
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA