title: Technetium-99m-L,L-ethylenedicysteine is more effective than technetium-99m diethylenetriamine penta-acetic acid for excluding obstruction in patients with pyelocalicinal dilation.
abstract: OBJECTIVE
  To evaluate the utility of diuretic dynamic renal scintigraphy (DDRS) with technetium-99m-L,L-ethylenedicysteine ((99m)Tc-EC) in patients with indeterminate or possible false-positive results for urinary obstruction by technetium-99m diethylenetriamine penta-acetic acid ((99m)Tc-DTPA) DDRS.
  
  
  METHODS
  A total of 92 patients (63 male; mean age, 16.6 +/- 21.25 years) were studied, with a total of 103 kidneys presenting indeterminate (20/103) or possible false-positive results for obstruction attributable to reduced renal function or severe kidney dilation (83/103) by (99m)Tc-DTPA DDRS (<60% of radiopharmaceutical excreted in 20 minutes-half-time clearance [T(1/2)] >15 minutes). Patients were reimaged after intravenous injection of (99m)Tc-EC, with dynamic images before and after furosemide administration using the same acquisition parameters applied in the previous (99m)Tc-DTPA study. Time interval between (99m)Tc-DTPA and (99m)Tc-EC renograms was 2-64 days. The percentage of excreted material 20 minutes after furosemide was calculated using both radiopharmaceuticals, and were statistically compared using the paired samples t test.
  
  
  RESULTS
  The excretion after furosemide injection was 25.3% +/- 18.2% for (99m)Tc-DTPA and 41.2% +/- 26.1% for (99m)Tc-EC, with a statistically significant difference between both radiopharmaceuticals (P <.0001). Using (99m)Tc-EC obstruction was excluded in 36 of 103 kidneys, which excreted >60%. A total of 10 of 83 kidneys (12.0%) with an obstructive pattern by (99m)Tc-DTPA study turned out to be indeterminate by (99m)Tc-EC DDRS. There was an agreement between (99m)Tc-EC and (99m)Tc-DTPA studies in 54 of 83 kidneys with obstructive (65.1%) and in 3 of 20 (15.0%) with indeterminate patterns.
  
  
  CONCLUSIONS
  (99m)Tc-EC was more effective than (99m)Tc-DTPA for excluding obstruction, presenting less false-positive and indeterminate results. (99m)Tc-EC can substitute (99m)Tc-DTPA to evaluate patients with urinary tract dilation.
authors.affiliation: Division of Nuclear Medicine, Department of Radiology, State University of Campinas, Campinas, São Paulo, Brazil. mar.lima@terra.com.br
authors.forename: Mariana C L
authors.initials: MC
authors.lastname: Lima
authors.forename: Marcelo Lopes
authors.initials: ML
authors.lastname: de Lima
authors.forename: Carlos F V
authors.initials: CF
authors.lastname: Pepe
authors.forename: Elba C S C
authors.initials: EC
authors.lastname: Etchebehere
authors.forename: Allan O
authors.initials: AO
authors.lastname: Santos
authors.forename: Bárbara J
authors.initials: BJ
authors.lastname: Amorim
authors.forename: Edwaldo E
authors.initials: EE
authors.lastname: Camargo
authors.forename: Ubirajara
authors.initials: U
authors.lastname: Ferreira
authors.forename: Paulo C R
authors.initials: PC
authors.lastname: Palma
authors.forename: Celso D
authors.initials: CD
authors.lastname: Ramos
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D003545:Cysteine / Q000031:analogs & derivatives*; D004108:Dilatation, Pathologic; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D007223:Infant; D007682:Kidney Pelvis; D008297:Male; D008875:Middle Aged; D015609:Organotechnetium Compounds; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D016284:Technetium Tc 99m Pentetate; D014517:Ureteral Obstruction / Q000000981:diagnostic imaging*; D055815:Young Adult
chemical_list: D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; C073806:technetium Tc 99m-ethylenedicysteine; D003545:Cysteine; D016284:Technetium Tc 99m Pentetate