Zhao Yiwu, Zhang Chenxi, Liu Songde, Tian Chao
Opt Lett. 2022 Aug 1;47(15):3960-3963. doi: 10.1364/OL.462799.
Image formation in photoacoustic tomography (PAT) is generally based on the assumption that biological tissues are acoustically homogeneous. However, this does not hold, especially when strongly heterogeneous tissues, such as bones and air cavities, are present. Tissue heterogeneity can cause acoustic reflection, refraction, and scattering at interfaces, which may create distortions and artifacts in final images. To mitigate this problem, we propose an adaptive photoacoustic (PA) image reconstruction method based on prior structural information of an acoustically heterogeneous region extracted from ultrasound images. The method works in three steps: acoustic heterogeneity identification via ultrasound imaging; acoustically heterogeneous region segmentation; and adaptive time-domain raw data truncation and image reconstruction. The data truncation is based on a variable cutoff time, which can be adaptively determined according to the relative position of a transducer and an acoustically heterogeneous region. Numerical and in vivo experimental imaging results of human fingers demonstrate that the proposed ultrasound-guided adaptive image reconstruction method can effectively suppress acoustic heterogeneity-induced artifacts and substantially improve image quality. This work provides a practical way to mitigate the influence of acoustic heterogeneity in PAT.
光声断层成像（PAT）中的图像形成通常基于生物组织在声学上是均匀的这一假设。然而，实际并非如此，尤其是当存在诸如骨骼和气腔等高度异质的组织时。组织异质性会在界面处引起声反射、折射和散射，这可能会在最终图像中产生畸变和伪影。为了缓解这个问题，我们提出了一种基于从超声图像中提取的声学异质区域的先验结构信息的自适应光声（PA）图像重建方法。该方法分三步进行：通过超声成像识别声学异质性；分割声学异质区域；以及自适应时域原始数据截断和图像重建。数据截断基于可变截止时间，该时间可以根据换能器与声学异质区域的相对位置自适应确定。人体手指的数值和体内实验成像结果表明，所提出的超声引导自适应图像重建方法可以有效抑制声学异质性引起的伪影，并显著提高图像质量。这项工作提供了一种减轻PAT中声学异质性影响的实用方法。
