皮肤浅层血容积的三维动态表征研究

The pulse wave detected from the change of blood volume in skin can provide an important basis for the diagnosis of cardiovascular disease. Based on the technology of imaging photoplethysmography (iPPG), aiming at meeting the diagnostic needs of cardiovascular disease, this project focuses on the development of the non-contact and accurate way to obtain the reference pulse signals, and explores the penetration depths and their corresponding probabilities of light at different wavelengths. According to the discussion above, the modified Beer-Lambert Law is utilized to construct the photoplethysmographic image (PPGi) of blood volume at different skin depths. Combining the characteristics of dynamic visualization of PPGi with the capability of “tomography” at different wavelengths in depth direction can realize the construction of three-dimensional dynamic blood volume in the superficial skin. Furthermore, the actually collected data from patients with cardiovascular disease can elucidate the specific meanings of three-dimensional dynamic PPGi. Research results would provide a simple, non-contact, accurate, intuitive, and effective approach for the diagnosis of cardiovascular disease.

由皮肤血容积变化获得的脉搏波可为心血管疾病的诊断提供重要依据。本选题着眼于心血管疾病的诊断需求，以成像式光电容积描记法（iPPG）为技术基础，重点探讨非接触参考脉搏波信号的精确获取方法和不同波长光的皮肤穿透深度及其对应的穿透概率。在此基础上，利用修正比尔-朗伯定律构建皮肤浅层不同深度下的血容积图（PPGi），结合血容积图自身的动态可视化特征与不同波长光在深度方向上的“层析”能力，实现皮肤浅层感兴趣区域血容积的三维动态构建。通过心血管疾病患者的三维动态血容积图来表征其相应的患病类型，以期为心血管疾病的诊断提供简单、非接触、准确、直观且有效的手段。

项目着眼于心血管疾病的诊断需求，以成像式光电容积描记法（iPPG）为技术基础，围绕基于视频成像的脉搏波信号非接触、精确获取和皮肤浅层血容积图的构建方法开展了相关工作。基于建立的衡量脉搏波信号质量的信噪比模型，实现了用于脉搏波计算的皮肤组织参考区域的位置和大小的有效选取；建立了皮肤组织的六层层状模型，基于蒙特卡洛模拟法阐明了不同波长光对应的脉搏波幅度、穿透深度以及脉搏波的产生深度，为皮肤浅层组织脉搏波的精确获取提供理论依据和技术途径；采用视频图像的全局运动跟踪和克服微小运动的R、G、B三通道映射方法实现了自然条件下抗运动干扰、光照变化的非接触脉搏波信号的精确获取；提出了基于选取的皮肤组织区域构建全局参考脉搏波信号，后与视频图像各像素点脉搏波信号互相关实现皮肤浅层血容积图的构建方法；搭建了同时实现多光谱容积脉搏波信号获取和视频成像的双光路非接触容积脉搏波测量装置，结合修正比尔朗伯定律与容积脉搏波的光谱特性，实现了皮肤浅层感兴趣区域血容积的三维动态表征。相关研究成果为人体健康诊断提供了简单、非接触、准确、直观且有效的手段。