title: Reliability of 99mtechnetium dimercapto-succinic acid uptake 2 hours after injection in hydronephrosis.
abstract: OBJECTIVE
  The accumulation of radioactivity in the dilated collecting system potentially influences the calculation of differential renal function on the radionuclide test. We focused on this reservoir effect in unilateral hydronephrosis and assessed the reliability of calculating differential renal function by dimercapto-succinic acid (DMSA) uptake 2 hours after injection.
  
  
  METHODS
  Unilateral partial ureteral obstruction was created in 8-week-old rats. Four weeks after surgery the animals were sacrificed 2 and 24 hours after the injection of tracer. The DMSA uptake rates of the renal parenchyma and collecting system were measured separately by autowell gamma counter. Differential function was calculated according to renal parenchymal and whole kidney (parenchyma and collecting system) uptake.
  
  
  RESULTS
  There was a higher accumulation of DMSA in the dilated renal pelvis at 2 than at 24 hours. However, DMSA uptake in the collecting system was extremely small in comparison to that in the parenchyma. As a result; differential renal function calculated using parenchymal uptake was similar to that calculated using whole kidney uptake measured 2 and 24 hours after injection.
  
  
  CONCLUSIONS
  Our data suggest that the pure reservoir effect of DMSA uptake at early measurement is much smaller than reported in previous experimental animal studies. Further clinical studies are needed to reexamine this reservoir effect in children with unilateral hydronephrosis.
authors.affiliation: Department of Urology, Tokyo Women's Medical College, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Yamazaki
authors.forename: B B
authors.initials: BB
authors.lastname: Shi
authors.forename: R
authors.initials: R
authors.lastname: Yago
authors.forename: H
authors.initials: H
authors.lastname: Toma
mesh_terms: D000818:Animals; D006869:Hydronephrosis / Q000378:metabolism*; D007267:Injections; D015609:Organotechnetium Compounds / Q000008:administration & dosage / Q000493:pharmacokinetics*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results; D004113:Succimer / Q000008:administration & dosage / Q000493:pharmacokinetics*; D019783:Technetium Tc 99m Dimercaptosuccinic Acid; D013997:Time Factors; D014517:Ureteral Obstruction / Q000378:metabolism*
chemical_list: D015609:Organotechnetium Compounds; D019783:Technetium Tc 99m Dimercaptosuccinic Acid; D004113:Succimer