基于SE序列的MR图像权重计算方法

A Method of MR Imaging Weighted Calculation Based on SE Sequence

目的:探究一种基于SE序列的MR图像权重计算方法,为判定SE加权像提供更加科学及准确的判定依据。方法:提出一种计算两种生物组织的质子密度特性差异、纵向弛豫时间特性差异及横向弛豫时间特性差异各自对磁共振图像对比度的贡献比例方法,首先,将磁共振图像对比度公式进行等量变换,建立SE序列权重对比度数学关系式;其次,对该关系式进行对数变换,在对数坐标下,乘性权重因子转化为加性权重因子;最后,利用比例计算公式计算生物组织的三种特性差异各自对磁共振图像的贡献比例。结果:利用医用核磁共振仪器,通过对重复时间及回波时间不同设置后,获得两幅关于白质和灰质的MR图像,然后利用本文介绍的基于SE序列的MR图像权重计算方法,获得质子密度特性差异、纵向弛豫时间特性差异及横向弛豫时间特性差异各自对MR图像对比度贡献比例,并显示于这两幅MR图像上,可定量判定SE加权像。结论:通过本文介绍的基于SE序列的MR图像权重计算方法,对精确判定磁共振SE加权像有极大的帮助。

Objective： Explore a method of MR imaging weighted calculation based on SE sequenco to provide more scientif- ic and accurate judgment basis for determining the SE-weighted imaging. Methods： Propose a method of calculating about two kinds of tissue proton density characteristic differences, longitudinal relaxation time characteristic differences and trans- verse relaxation time characteristic differences in the contribution of MR imaging contrast proportion, Firstly, establish mathe- matical relationships of SE sequence weighted contrast. Secondly, mathematical relationships of this equation can convert mul- tiplicative weighted factor into additive one in logarithmic coordinates. Lastly, use proportion calculation method to calculate contribution proportion of three kinds of biological tissue differences to MR imaging. Results： Get two MR imaging figure about white matter and gray matter using medical magnetic resonance equipment and setting different repetition time and echo time. Then, obtain proton density characteristic differences, longitudinal relaxation time characteristic differences and trans- verse relaxation time characteristics differences in the contribution of the MR image contrast ratio which show on two MR imaging figures, using method of MR imaging weighted calculation based on SE sequence. This can quantitatively determine the SE-weighted imaging. Conclusions： It is much helpful to obtain a more accurate SE-weighted imaging through this method.