Xie Zhiying, Wang Geng, Cheng Yuxuan, Zhang Qinqin, Le Minh Nhan, Wang Ruikang K
Department of Bioengineering, University of Washington, Seattle, WA, USA.
Quant Imaging Med Surg. 2021 Mar;11(3):907-917. doi: 10.21037/qims-20-778.
Photoplethysmography (PPG) is routinely used to detect the blood pulse signal from skin tissue beds in clinics. However, the origin of the PPG signal remains controversial. The purpose of this study is to explore optical coherence tomography angiography (OCTA) to indicate pulsatile waveforms in the papillary plexus and dermal plexus separately under different hand elevations.
Optical microangiography (OMAG) algorithm was used to obtain a 3D OCTA signals, from which the depth-resolved pulsatile blood flow signals were extracted from different skin vascular plexus. The systolic amplitude, crest time, and delta T were measured from the OCTA pulsatile signals when the hand was placed at the positions of 50 cm below, 0 cm, and 50 cm above the heart level.
The pulse signal integrated from all the depths has a similar waveform to that of the PPG and showed the same morphological change at different hand elevations. The pulsatile patterns from the papillary plexus and dermal plexus showed distinct morphological changes at different local blood pressure. Less amplitude difference was found from papillary plexus comparing to that of the dermal plexus. Crest time was found in an increasing trend in the OCTA pulsatile waveform from both plexuses when the arm was raised from the position below to above the heart level. In contrast, a decreasing trend of Delta T was detected in the dermal pulsatile but was not observed from that of the papillary plexus, indicating that vascular resistance associated with the arm elevations does not necessarily have the same effect on the two plexuses.
OCTA can provide depth-resolved pulsatile waveforms within different microvascular plexus within tissue skin beds. This technique could open doors to understanding the mechanisms of how blood flow changes at different skin circulatory plexus.
光电容积脉搏波描记法（PPG）在临床上常用于检测来自皮肤组织床的血脉冲信号。然而，PPG信号的起源仍存在争议。本研究的目的是探索光学相干断层扫描血管造影（OCTA），以分别显示在不同手部抬高情况下乳头层血管丛和真皮层血管丛中的搏动波形。
使用光学微血管造影（OMAG）算法获取三维OCTA信号，从中提取不同皮肤血管丛的深度分辨搏动血流信号。当手置于心脏水平以下50厘米、0厘米和心脏水平以上50厘米的位置时，从OCTA搏动信号中测量收缩期幅度、波峰时间和ΔT。
从所有深度积分得到的脉搏信号具有与PPG相似的波形，并且在不同手部抬高情况下显示出相同的形态变化。乳头层血管丛和真皮层血管丛的搏动模式在不同局部血压下显示出明显的形态变化。与真皮层血管丛相比，乳头层血管丛的幅度差异较小。当手臂从心脏水平以下位置抬高到心脏水平以上位置时，两个血管丛的OCTA搏动波形中的波峰时间均呈上升趋势。相比之下，真皮层搏动中检测到ΔT呈下降趋势，但乳头层血管丛未观察到，这表明与手臂抬高相关的血管阻力对两个血管丛的影响不一定相同。
OCTA可以提供皮肤组织床内不同微血管丛的深度分辨搏动波形。这项技术可能为理解不同皮肤循环血管丛中血流变化的机制打开大门。
