99mTc-MAEC Complexes: New Renal Radiopharmaceuticals Combining Characteristics of 99mTc-MAG3 and 99mTc-EC

Journal of Nuclear Medicine

Eugene Malveaux¹  Luigi G. Marzilli¹  Malgorzata Lipowska¹  Andrew T. Taylor¹  Lory Hansen¹ 

关键词: ^99mTc-mercaptoacetamide-ethylene-cysteine;    ^99mTc-ethylenedicysteine;    ^99mTc-mercaptoacetyltriglycine;    renal radiopharmaceuticals;   

DOI  :  

学科分类：医学（综合）

来源: Society of Nuclear Medicine

【 摘 要 】

99mTc-Mercaptoacetyltriglycine (99mTc-MAG3) and 99mTc-l,l-ethylenedicysteine (99mTc-ll-EC) are useful renal radiopharmaceuticals; however, both agents have renal clearances less than that of 131I-orthoiodohippurate (131I-OIH), and 99mTc-ll-EC exists in dianionic and monoanionic forms at physiologic pH. In an effort to develop a superior 99mTc agent with a rapid clearance comparable with that of 131I-OIH, we have designed a new ligand system, mercaptoacetamide-ethylene-cysteine (MAEC), which combines important structural features of both MAG3 and EC. Methods: Biodistribution and clearance studies were performed on Sprague–Dawley rats using syn- and anti-99mTc-l- and -d-MAEC coinjected with 131I-OIH. Studies were also performed by coinjecting each isomer (∼74 MBq [∼2 mCi]) and 7.4–11.1 MBq (200–300 μCi) of 131I-OIH in 3 volunteers with dual-isotope imaging performed using a camera system fitted with a high-energy collimator. Blood samples were obtained from 3 to 90 min after injection and urine samples were obtained at 30, 90, and 180 min. Results: In the rats, <10% of the injected dose remained in the blood at 10 min after injection for all isomers, and the urine dose at 60 min ranged from 84% to 99% that of 131I-OIH. The clearances of syn- and anti-99mTc-l-MAEC in the rats were higher than the clearances for the d-isomers (P ≤ 0.02) and were 102% and 105% that of 131I-OIH, respectively. In humans, the plasma protein binding of the 99mTc-MAEC complexes ranged from 82% to 89%. All 4 complexes provided excellent renal images. The 99mTc-MAEC complex/131I-OIH plasma clearance ratio in humans ranged from 45% (anti-99mTc-l-MAEC) to 74% (syn-99mTc-d-MAEC) with the 180-min urine excretion equivalent to that of 131I-OIH for all 4 complexes. Conclusion: Initial data in humans suggest that syn-99mTc-d-MAEC has a higher clearance than that of 99mTc-MAG3; however, none of the 99mTc-MAEC tracers have a clearance equivalent to that of 131I-OIH and further ligand design is needed.

【 授权许可】

Unknown