Clinical evaluation of technetium-99m-L,L-ethylenedicysteine in patients with chronic renal failure

Technetium-99m-L,L-ethylenedicysteine (Tc-99m-L,L-EC), a new renal radiopharmaceutical, has been shown to have similar excretion characteristics but a higher plasma clearance than Tc-99m-mercaptoacetyltriglycine (Tc-99m-MAG3) in normal volunteers and patients with obstructive nephropathy. This study evaluated Tc-99m-L,L-EC in patients with chronic renal failure. Methods: The clearance of Tc-99m-L,L,-EC was compared with that of I-125-hippuran in 26 patients with varying degrees of chronic renal impairment (serum creatinine 168-1163 mu mol/liter). All 26 patients also were imaged with Tc-99m-L,L-EC (70-80 MBq). Fifteen patients had further imaging with Tc-99m-MAG3 (100 MBq) the following day. Results: A subjective analysis of the (TC)-T-99m-L,L-EC images revealed that all were of acceptable quality regardless of creatinine level. In the 15 patients who were imaged with both Tc-99m-L,L-EC and Tc-99m-MAG3, general image quality and target-to-background ratio were similar. Time-activity curves and mean parenchymal transit times obtained with the two agents were almost identical. Plasma clearance values (mean +/- s.d.) of Tc-99m-L,L-EC and I-125-hippuran were 81 +/- 68 ml/min and 114 +/- 104 ml/min, respectively. Mean Tc-99m-L,L-EC clearance was 71% of the mean I-125-hippuran value. Conclusion: Technetium-99m-L,L-EC provides equally high-quality images to Tc-99m-MAG3 in patients with chronic renal failure. Technetium-99m-L,L-EC clearance more closely resembles that of hippuran than does Tc-99m-MAG3 clearance. These features together with its ease of preparation make Tc-99m-L,L-EC an attractive alternative to Tc-99m-MAG3 in patients with chronic renal failure