Technetium-99m-L,L-Ethylenedicysteine Is More Effective Than Technetium-99m Diethylenetriamine Penta-acetic Acid for Excluding Obstruction in Patients With Pyelocalicinal Dilation
Received 29 November 2009; accepted 20 December 2009. published online 08 March 2010. Corrected Proof
Objective
To evaluate the utility of diuretic dynamic renal scintigraphy (DDRS) with technetium-99m-L,L-ethylenedicysteine (99mTc-EC) in patients with indeterminate or possible false-positive results for urinary obstruction by technetium-99m diethylenetriamine penta-acetic acid (99mTc-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 99mTc-DTPA DDRS (<60% of radiopharmaceutical excreted in 20 minutes—half-time clearance [T½] >15 minutes). Patients were reimaged after intravenous injection of 99mTc-EC, with dynamic images before and after furosemide administration using the same acquisition parameters applied in the previous 99mTc-DTPA study. Time interval between 99mTc-DTPA and 99mTc-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 99mTc-DTPA and 41.2% ± 26.1% for 99mTc-EC, with a statistically significant difference between both radiopharmaceuticals (P <.0001). Using 99mTc-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 99mTc-DTPA study turned out to be indeterminate by 99mTc-EC DDRS. There was an agreement between 99mTc-EC and 99mTc-DTPA studies in 54 of 83 kidneys with obstructive (65.1%) and in 3 of 20 (15.0%) with indeterminate patterns.
Conclusions
99mTc-EC was more effective than 99mTc-DTPA for excluding obstruction, presenting less false-positive and indeterminate results. 99mTc-EC can substitute 99mTc-DTPA to evaluate patients with urinary tract dilation.
aDivision of Nuclear Medicine, Department of Radiology, State University of Campinas (UNICAMP), Campinas, São Paulo, Brazil
bDivision of Urology, Department of Surgery, State University of Campinas (UNICAMP), Campinas, São Paulo, Brazil
Reprint requests: Mariana C. L. Lima, M.D., Serviço de Medicina Nuclear Av. Zeferino Vaz, s/n, Caixa Postal 6142, Campinas/SP–Brazil, CEP 13081-970
ABSTRACT