目的　探讨以凝血酶为靶，重组水蛭素（ｒＨ）为配基进行血栓显像的潜在价值。方法　氯胺Ｔ法制备１２５ＩｒＨ，采用体外放射配体结合法分析ｒＨ对凝血酶纤维蛋白复合物的亲和、定量关系和时间反应动力学。亚氨基噻吩盐酸盐修饰法制备９９ＴｃｍｒＨ，进行小鼠体内分布测定及犬动、静脉血栓模型显像。结果　ｒＨ 不能直接与纤维蛋白原结合，当凝血酶与纤维蛋白形成复合物后才能与其形成三元复合物，且这种结合呈高亲和、特异和可逆性。９９ＴｃｍｒＨ 在小鼠心、脑、肝、脾、肺摄取低，肾摄取高，１５ ｍｉｎ 达（６４－７２４±５－０４２） ％ＩＤ／ｏｒｇａｎ，血清除迅速。犬股动脉血栓于４５ ｍｉｎ 可清晰显影，靶／ 本底（Ｔ／Ｂ） 比值为１－４７。静脉血栓于注药后３０ ｍｉｎ 就出现浓聚，并随时间延长血栓显影更清晰，１ ｈ Ｔ／Ｂ比值为１－５３。结论　９９ＴｃｍｒＨ 有望成为１ 种新的较理想的血栓示踪剂 Objective To investigate the potential value of thrombus imaging using thrombin as target and recombinant hirudin (rH) as ligand. Methods Chloramine  T 125I  rH prepared by in vitro radioligand binding assay rH thrombin  fibrin composite affinity, quantitative relationship and time reaction kinetics. Iminothiophene hydrochloride modified method Preparation 99Tcm  rH, the distribution of the mice were measured and canine venous thrombosis model. As a result, rH can not directly bind to fibrinogen, and thrombin forms a complex with fibrin to form a ternary complex with it, and the binding is highly affinity, specificity and reversibility. 99Tcm  rH in mice heart, brain, liver, spleen, lung uptake low, high renal uptake, 15 min up to (64-724 ± 5-042)% ID / organ, serum addition to rapid. Canine femoral artery thrombosis at 45 min can be clearly developed, target / background (T / B) ratio of 1-47. Thromboembolism occurred at 30 min after injection, and thrombosis became clearer with time. The 1 h T / B ratio was 1-53. Conclusion 99Tcm  rH is expected to become a new kind of more ideal thrombus tracer