校正光通量变化的定量光声内窥成像  

Quantitative Photoacoustic Endoscopic Imaging for Correcting Light Fluence Variation

作　　者：孟琪 孙正[1,2] 侯英飒 孙美晨 Meng Qi;Sun Zheng;Hou Yingsa;Sun Meichen(Department of Electronic and Communication Engineering,North China Electric Power University,Baoding 071003,Hebei,China;Hebei Key Laboratory of Power Internet of Things Technology,North China Electric Power University,Baoding 071003,Hebei,China)

机构地区：[1]华北电力大学电子与通信工程系,河北保定071003 [2]华北电力大学河北省电力物联网技术重点实验室,河北保定071003

出　　处：《光学学报》2023年第1期69-81,共13页Acta Optica Sinica

基　　金：国家自然科学基金(62071181)。

摘　　要：在光声内窥成像中,不均匀或不稳定的照明,以及生物组织的复杂光学特性均会导致成像平面内光通量分布不均匀,从而造成重建图像质量和成像深度的下降。提出了一种校正光通量变化的定量光声内窥成像方法,对光吸收能量分布进行稀疏分解,采用贪婪算法重构得到光吸收系数和光通量的稀疏表示,并通过稀疏矩阵分解实现光吸收系数与光通量分布的联合重建。仿真和体模实验结果表明,与一步法和基于模型的定量重建方法相比,采用所提方法估算光吸收系数的均方根误差(RMSE)可降低约48%,重建图像的归一化平均绝对距离(NMSAD)和结构相似度(SSIM)可分别降低约25%和提高约24%。与其他校正光通量的重建算法相比,所提方法估计光吸收系数的RMSE可降低约22%、NMSAD可降低约20%、SSIM可提高约10%。Objective Photoacoustic imaging(PAI) is an emerging imaging modality that provides structural and functional information on biological tissue, with the advantages of high contrast of optical imaging and high penetration depth of ultrasound imaging. Photoacoustic endoscopic imaging is an endoscopic application of PAI, which combines non-invasive PAI with endoscopic detection technology. This imaging modality is physically based on the photoacoustic effect of biological tissue illuminated by short laser pulses. The absorbed optical energy density is proportional to the product of the optical absorption coefficient and the local light fluence. Therefore, light fluence is related not only to the optical properties of the tissue but also to the distribution of irradiation intensity. The optical properties of the tissue cannot be accurately reflected in the distribution image of absorption energy density. By solving the optical inverse problem, the optical property parameters can be estimated quantitatively to realize quantitative imaging. Due to the complex optical properties of tissue and non-uniform and non-stationary illumination, photoacoustic image reconstruction is subject to non-uniform light fluence, which leads to a reduction in image quality and imaging depth. The purpose of this work is to solve the problem of reduced accuracy of quantitative imaging due to light fluence variation.Methods A quantitative image reconstruction method for photoacoustic endoscopic imaging is presented to correct light fluence variation. It employs a two-step scheme. Firstly, the distribution of absorbed optical energy density on the crosssection of the tubular object is recovered from the photoacoustic signal measured by the ultrasonic detector with conventional image reconstruction methods such as back projection and time reversion. Secondly, the sparse representation of the distribution of absorbed optical energy density is constructed by the weighted sum of a finite number of discrete Curvelet and Haar joint basis functions.

关 键 词：成像系统 图像重建技术 光声成像 内窥成像 光吸收系数 光通量 定量成像 

分 类 号：TP391[自动化与计算机技术—计算机应用技术]