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虚拟内窥镜中基于褶皱预匹配的结肠配准研究_NCIG2016

郭志飞,段侪杰,梁正荣(清华大学深圳研究生院;美国纽约州立大学石溪分校放射学系)

摘 要
目的:虚拟结肠镜是一种采用CT或者MRI图像重建出结肠三维结构,通过漫游虚拟结肠来检测结肠组织,一般用于早期结直肠癌筛查。结肠配准能够有效的帮助提高息肉检测的效率和精确度,但由于仰卧和俯卧位下的结肠图像形变太大,传统配准方案基本无法得到正确的结果。方法:本文提出了一种新的结肠图像配准方法,能够完成不同体位获取的虚拟结肠图像之间的配准。首先提取可以反映结肠结构信息的皱襞特征,用模板匹配和特征匹配方法找出两幅结肠中匹配的皱襞对。然后将匹配对的中心点作为标记点,做基于标记点的非刚性配准,最后将两幅图做B样条配准完成细配准。这种方法能够将结肠内部较大的形变先矫正,使得两幅图之间的形变缩小到一定范围,然后利用传统配准方法能够完成配准。结果:在10套数据中,找到能够成功匹配的皱襞区域数量占所有分割出的皱襞区域总数量的55%左右,匹配错误率为6%左右,没检测到的匹配皱襞所占比例为8%左右。完成皱襞粗配准后,结肠形变明显趋于一致,灰度值相对误差减小,最终完成了结肠配准。讨论:先进行皱襞匹配再做基于匹配好的皱襞的映射关系做结肠配准,能够将存在较大形变的两套结肠匹配起来。但做配准评估时,单纯采用灰度差值不能很好完成评估,需要其它评估标准辅助评估。
关键词
A method of colon registration based on pre-match of haustral fold in virtual colonoscopy

guozhifei,duanchaijie,liangzhengrong(graduate school at ShenZhen, Tsinghua University;Department of Radiology, New York State University, Stony Brook)

Abstract
Objective The virtual colonoscopy is a method that looking through the 3D structure of colon which reconstructed by CT or MRI images and detect colon tissue especially the polypus. Colon registration can greatly improve the efficiency and accuracy of polyp detection in virtual colonoscopy, but the traditional registration can’t accomplish that due to the drastic change in position of the patient in supine and prone. Method In this paper, we propose a new method of colon registration that can complete the image registration acquired in different position. First, extract the haustral fold that can reflect the information of fold structure. Get the matched haustral folds using the method of template matching and feature matching. Then do the non-rigid registration based in the center of matched haustral folds. Using b-spline registration to completed the fine registration of the two pictures finally. This method can retrieve the drastic change in the colon image, make the change of the two image within certain limits, and the traditional registration method can be used. Result There are about fifty percent haustral fold can be matched among ten sets of data. The rate of matching error is six percent and eight percent of haustral fold can not be find. The colonic deformation decreased after the rough registration of the folds.,that make the two colon images can be registered using the tradition register method. we had accomplished the registration of colon images finally. Conclusion When doing the rough registration of the two colon image, the deformation of two colon images can be corrected. However, when doing registration evaluation,we can not complete the assessment simply using the difference of gray-scale, so we should make some other criteria to assist the assessment.
Keywords
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