光声计算断层图像重建中声速异质性补偿方法  

Speed-of-Sound Heterogeneity Compensation Method in Photoacoustic Computed Tomographic Image Reconstruction

作　　者：邓可欣 崔曼修 左宏志 王铉皓 蔡创坚 罗建文[1] 马骋 Deng Kexin;Cui Manxiu;Zuo Hongzhi;Wang Xuanhao;Cai Chuangjian;Luo Jianwen;Ma Cheng(Department of Biomedical Engineering,Tsinghua University,Beijing 100086;Department of Electronic Engineering,Tsinghua University,Beijing 100086)

机构地区：[1]清华大学生物医学工程系,北京100086 [2]清华大学电子工程系,北京100086

出　　处：《中国激光》2021年第15期276-288,共13页Chinese Journal of Lasers

基　　金：国家自然科学基金(61735016,61971265)。

摘　　要：光声计算断层成像是近年发展起来的一种非入侵式和非电离式的新型生物医学成像方法,其临床应用对成像精度要求较高。生物组织内声速分布的不均匀性时常造成重建的光声图像中存在较为严重的伪影。实现光声IP和声速分布的联合重建是改善成像效果、去除成像伪影的重要途径之一,也是仅通过光声单一模态的信息获取就可以获得多模态信息(包括光学和声学信息)的崭新途径。总结了几种本研究组近年来开发的光声-声速联合重建方法,包括基于特征耦合、基于波前整形以及基于信号互补的方法。同时,分析了这几种方法的优劣势和适用场景,以期帮助人们更好地利用这些方法解决光声图像质量提高和多模态图像获取的问题。Significance Photoacoustic tomography(PACT)is a novel medical-imaging modality.During the imaging process,biological tissues are irradiated by nanosecond ultrashort light pulse.Fast energy deposition in tissues causes thermoelastic expansion and generates ultrasound emission.Such emissions can be detected by ultrasonic detectors.The penetration depth of PACT(>5 cm)is much higher than that of most optical-imaging modalities,approaching that of ultrasonic imaging.Therefore,PACT has wide potential applications in areas such as blood pressure monitoring,cancer detection,and small-animal studies.PACT reconstruction requires knowledge of distribution of speed-of-sound(SoS).In practice,acoustic properties of biological tissues are inhomogeneous and unknown,resulting in image degradation in PACT.In its simplest implementation,PACT reconstruction assumes single SoS for both biological tissues and surrounding acoustic-coupling medium(i.e.,water in most cases).However,considering that the SoS inside soft tissues varies from 1350 m/s(fat)to 1700 m/s(skin),such an assumption can sometimes be too idealized,resulting in splitting,blurring,and distortion of structural features.Furthermore,the SoS of a range of tumors is much higher than that of normal tissues.Therefore,imaging degradation is much severe in tumor imaging.To solve this problem,a more rigorous acoustic model is required during the reconstruction process.Some studies have employed ultrasound devices for directly imaging the distribution of SoS.However,the most effective method is the joint reconstruction of initial sound pressure(IP)and SoS.Presently,there are several methods for joint reconstruction.Each method has advantages and disadvantages and is effective in different scenarios.Herein,we introduce several methods developed by our teams and summarize their advantages and disadvantages,supporting the biomedical application of PACT.Progress The ring-array PACT system(Fig.1)is widely used in IP-SoS joint reconstruction.Most jointreconstruction methods are based on

关 键 词：医用光学 光声成像 医学影像 声速矫正 声速断层成像 多模态成像 

分 类 号：R445.9[医药卫生—影像医学与核医学]