融合块匹配和插值法的膈肌应变估计及分析  

Diaphragm strain estimation and analysis using block matching algorithm and interpolation method

作　　者：刘子玲 刘巧红 叶熊 撖子奇 LIU Ziling;LIU Qiaohong;YE Xiong;HAN Ziqi(School of Health Science and Engineering,University of Shanghai for Science and Technology,Shanghai 200093,China;School of Medical Instruments,Shanghai University of Medicine and Health Sciences,Shanghai 201318,China;School of Clinical Medicine,Shanghai University of Medicine and Health Sciences,Shanghai 201318,China)

机构地区：[1]上海理工大学健康科学与工程学院,上海200093 [2]上海健康医学院医疗器械学院,上海201318 [3]上海健康医学院临床医学院,上海201318

出　　处：《中国医学物理学杂志》2022年第11期1360-1368,共9页Chinese Journal of Medical Physics

基　　金：国家自然科学基金(61801288)。

摘　　要：为了准确评估膈肌收缩功能,提出一种融合块匹配法和插值法的膈肌运动位移和应变估计方法。首先利用基于归一化互相关的块匹配法结合膈肌生理约束特性估计出膈肌感兴趣区域的互相关函数,对膈肌运动的整数位移进行估计;然后利用9点抛物线插值算法对互相关函数进行插值处理,进一步计算膈肌感兴趣区域二维亚像素位移;接下来根据估计出的位移计算应变;最后利用反追踪的思想选取最佳窗口的大小,以降低位移追踪误差。按照上述方法,分别针对吸气相超声膈肌全序列图像以及含吸气开始和吸气结束的首尾两张膈肌图像进行追踪,观察不同大小感兴趣区域窗口设置对膈肌运动位移和应变估计的影响。实验结果表明块匹配算法的窗口大小选择中,5×10和10×15窗口存在匹配错误,15×20、20×25、25×30、30×35窗口追踪得到的水平位移和竖直位移均无显著差异,而固定窗口大小为25×30最佳;选择使用全序列图像和首尾两张图像对膈肌全局应变计算不存在显著差异。A method combining block matching algorithm with interpolation method is proposed to estimate diaphragm motion displacement and strain for evaluating diaphragm contractility accurately.According to the physiological restraint characteristics of the diaphragm,block matching algorithm based on normalized cross-correlation is used to estimate the cross-correlation function of the region of interest(ROI)of the diaphragm,thereby estimating the integer displacement of the diaphragm motion.Then,a 9-point parabolic interpolation algorithm is used to interpolate the cross-correlation function for obtaining the two-dimensional subpixel displacement of the diaphragm ROI,and the strain is calculated according to the estimated displacement.Finally,the optimal window size is confirmed using the idea of reverse tracking for reducing the displacement tracking error.The whole sequence images of the diaphragm in the inspiratory phase and the fore and aft images of the diaphragm obtained at the beginning and end of inspiratory phase are tracked by the proposed method to analyze the effects of different ROI window sizes on the estimations of diaphragm motion displacement and strain.Experimental results show that there are matching errors in 5×10 and 10×15 windows.The differences in horizontal and vertical displacements tracked by windows of 15×20,20×25,25×30 and 30×35 are trivial,and the optimal window size is 25×30.There is no significant difference in diaphragm global strain calculated in whole sequence images or fore and aft images.

关 键 词：膈肌 超声图像 块匹配算法 插值法 应变估计 

分 类 号：R318[医药卫生—生物医学工程]