数字减影血管造影( DSA) 通过向血管中注入造影剂, 使血管的整体影像的对比度有了明显的增强, 然后通

过造影前后图像的相减运算, 可以去除非血管器官的影像, 得到血管更清晰的图像, 目前广泛应用于心血管疾病的

诊断。由于患者的呼吸运动, 使得不同时间采集的图像相减后会产生运动伪影。为了消除运动伪影, 从医生临床上

对于心脏的运动以胸腔的横膈膜为参考目标得到启发, 首先得到很多幅注入造影剂之前的图像( 掩膜图像) 和一幅

注入造影剂之后的图像( 造影图像) , 然后指定其中的一幅掩膜图像作为参考图像, 其它的掩膜图像和那一幅造影图

像分别对参考图像求位移。基于上面求出的位移, 可以将候选图像集中到位移小于某一阈值的很少的几幅图像上,

然后在这几幅图像上应用改造过的搜索算法, 最终找到了运动伪影最小的那幅掩膜图像。该算法引入了绝对位移

和相对位移相结合的方法使减影图像中运动伪影得到明显消除。-In dig ital subtr action ang io gr aphy ( DSA) , the co nt rast of the v essels is gr eatly improv ed w ith the injectio n

of contrast medium. In addit ion, mo re clear vessels can be visualized by eliminating the imag es o f non􀀁 vessel or gans,

and those imag es ar e called subtr action imag e o r DSA. Therefo re, DSA is o f w ide use for diag no sis o f car dio vascular

disease. Subtr action of imag es o bt ained befo re and after injection of contrast medium may cr eat e mo tion art ifacts due

to the aspiratio n o f pat ient s. In this reg ard, being motiv ated by the docto rs􀀂　ex per ience that t he displacement of dia􀀁

phragm can be used as the reference to measur e the hear t beat, we present a method to eliminate the mot ion ar tifacts.

In o ur method, fir stly , a set of DSA imag es are taken befo re injection o f contr ast medium, w hich are called mask

images!　 and one imag e taken after injection o f contrast is called targ et image! . Seco