Urology Journal

Abstract

Introduction: L,L-ethylenedicysteine (EC) is a new carrier of technetium Tc 99m (^99mTc) with a lower affinity to plasma albumin in comparison with diethylenetriamine pentaacetic acid (DTPA). We compared  ^99mTc-ECscan with ^99mTc-DTPA scan in diuretic renography for patients with obstructive uropathy.

Materials and Methods: Thirty-three patients with upper urinary tract obstruction were randomly selected and underwent diuretic renographies by ^99mTc-EC and ^99mTc-DTPA. The counts of radioisotope per pixel in the target (the kidney) and background tissues as well as the clearance half-life of these two radiopharmaceuticals were measured and compared. 

Results: Mean counts of radioisotope per pixel in the target tissue was not different between ^99mTc-EC and ^99mTc-DTPA scans, but in the background tissue, it was less for ^99mTc-EC (P = .003). Target-background ratio was higher for ^99mTc-EC scan (3.80 ± 2.11 versus 2.48 ± 1.39; P < .001). Renal clearance half-life of radioisotope was shorter for ^99mTc-EC scan than ^99mTc-DTPA scan (58.15 ± 15.17 minutes versus 78.65 ± 19.99 minutes; P = .033). The results were similar for uremic patients (with a serum creatinine level > 2mg/dL).

Conclusion: Target-background ratio of radiopharmaceutical uptake rates in diuretic renography was a good indicator of the higher resolution of ^99mTc-EC than ^99mTc-DTPA scan. We also demonstrated the faster clearance of ^99mTc-EC than ^99mTc-DTPA. This results in less radiation that is especially useful in children. To our opinion, ^99mTc-EC can better depict the kidneys in comparison with ^99mTc-DTPA.