Technetium-99m-L,L-ethylenedicysteine is more effective than technetium-99m diethylenetriamine penta-acetic acid for excluding obstruction in patients with pyelocalicinal dilation.
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.
Lima
Mariana C L
MC
Division of Nuclear Medicine, Department of Radiology, State University of Campinas, Campinas, São Paulo, Brazil. mar.lima@terra.com.br
de Lima
Marcelo Lopes
ML
Pepe
Carlos F V
CF
Etchebehere
Elba C S C
EC
Santos
Allan O
AO
Amorim
Bárbara J
BJ
Camargo
Edwaldo E
EE
Ferreira
Ubirajara
U
Palma
Paulo C R
PC
Ramos
Celso D
CD
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
D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; C073806:technetium Tc 99m-ethylenedicysteine; D003545:Cysteine; D016284:Technetium Tc 99m Pentetate