Liu Chang, Kılıç Kıvılcım, Erdener Sefik Evren, Boas David A, Postnov Dmitry D
Department of Biomedical Engineering, Boston University, Massachusetts 02215, USA.
Department of Bioengineering, Northeastern University, Massachusetts 02115, USA.
Biomed Opt Express. 2021 May 21;12(6):3571-3583. doi: 10.1364/BOE.426521. eCollection 2021 Jun 1.
Laser speckle contrast imaging (LSCI) is a real-time full-field non-invasive technique, which is broadly applied to visualize blood flow in biomedical applications. In its foundation is the link between the speckle contrast and dynamics of light scattering particles-erythrocytes. The mathematical form describing this relationship, which is critical for accurate blood flow estimation, depends on the sample's light-scattering properties. However, in biological applications, these properties are often unknown, thus requiring assumptions to be made to perform LSCI analysis. Here, we review the most critical assumptions in the LSCI theory and simulate how they affect blood flow estimation accuracy. We show that the most commonly applied model can severely underestimate the flow change, particularly when imaging brain parenchyma or other capillary perfused tissue (e.g. skin) under ischemic conditions. Based on these observations and guided by the recent experimental results, we propose an alternative model that allows measuring blood flow changes with higher accuracy.
激光散斑对比成像（LSCI）是一种实时全场非侵入性技术，广泛应用于生物医学领域以可视化血流情况。其基础是散斑对比度与光散射粒子（红细胞）动力学之间的联系。描述这种关系的数学形式对于准确估计血流至关重要，它取决于样本的光散射特性。然而，在生物应用中，这些特性往往是未知的，因此需要做出假设才能进行LSCI分析。在此，我们回顾LSCI理论中最关键的假设，并模拟它们如何影响血流估计的准确性。我们表明，最常用的模型可能会严重低估血流变化，尤其是在缺血条件下对脑实质或其他毛细血管灌注组织（如皮肤）进行成像时。基于这些观察结果并在近期实验结果的指导下，我们提出了一种替代模型，该模型能够更准确地测量血流变化。
