Bogdanov A A, Callahan R J, Wilkinson R A, Martin C, Cameron J A, Fischman A J, Brady T J, Weissleder R
Department of Radiology, Massachusetts General Hospital, Boston.
J Nucl Med. 1994 Nov;35(11):1880-6.
A synthetic blood pool imaging agent labeled with 99mTc is reported.
The agent, methoxypolyethylene glycol-poly-L-lysyl-diethylenetriaminepentaacetate monoamide was synthesized from a covalent graft copolymer of methoxypolyethylene glycol succinate (molecular weight 5.1 kD) and poly-L-lysine (molecular weight average 35.6 kD) with subsequent modification of the product with diethylenetriamineacetyl residues. The polymer was formulated into a kit that contained Sn(II) and sodium acetate for radiolabeling with 99mTc. Biodistribution studies were performed in rats. Blood-pool imaging and blood clearance determination was carried out in rabbits and in a rhesus monkey.
The 99mTc-labeled agent [specific activity greater than 3.7 GBq/mg; radiochemical purity more than 98% by thin-layer and high-performance liquid chromatography (HPLC)] demonstrated remarkable stability in solution (pH 5.5-6.5) with no radioactive products of degradation detectable by HPLC even at 24 hr postlabeling. The agent exhibited prolonged circulation in the blood with a half-life of 31.5 hr in rabbits. Biodistribution in rats showed a lack of substantial accumulation of the agent in the reticuloendothelial system. Sequential acquisitions were performed in a rhesus monkey. The 99mTc-labeled polymer kit was compared with the 99mTc-red blood cells (RBCs) labeled in vitro. Both methods produced similar heart-to-lung ratios. The ratios remained essentially unchanged for up to 15 hr postinjection.
The 99mTc-labeled methoxypolyethylene glycol-poly-L-lysyl-diethylenetriamine pentaacetate monoamide is an attractive alternative to radiolabeled RBCs for blood pool imaging applications.
报道了一种用99mTc标记的合成血池显像剂。
该显像剂甲氧基聚乙二醇-聚-L-赖氨酰-二乙三胺五乙酸单酰胺由甲氧基聚乙二醇琥珀酸酯（分子量5.1 kD）和聚-L-赖氨酸（平均分子量35.6 kD）的共价接枝共聚物合成，随后用二乙三胺乙酰残基对产物进行修饰。将该聚合物配制成试剂盒，其中含有用于用99mTc进行放射性标记的Sn(II)和醋酸钠。在大鼠中进行了生物分布研究。在兔子和恒河猴中进行了血池显像和血清除率测定。
99mTc标记的显像剂[比活度大于3.7 GBq/mg；通过薄层色谱和高效液相色谱（HPLC）测定放射化学纯度超过98%]在溶液（pH 5.5 - 6.5）中表现出显著的稳定性，即使在标记后24小时，HPLC也未检测到放射性降解产物。该显像剂在血液中循环时间延长，在兔子中的半衰期为31.5小时。大鼠的生物分布显示该显像剂在网状内皮系统中没有大量蓄积。在恒河猴中进行了序列采集。将99mTc标记的聚合物试剂盒与体外标记的99mTc红细胞（RBC）进行了比较。两种方法产生的心脏与肺的比值相似。注射后长达15小时，该比值基本保持不变。
99mTc标记的甲氧基聚乙二醇-聚-L-赖氨酰-二乙三胺五乙酸单酰胺是血池显像应用中放射性标记红细胞的一种有吸引力的替代物。
