Wårdell K, Jakobsson A, Nilsson G E
Department of Biomedical Engineering, Linköping University, Sweden.
IEEE Trans Biomed Eng. 1993 Apr;40(4):309-16. doi: 10.1109/10.222322.
Imaging of tissue perfusion is important in assessing the influence of peripheral vascular disease on microcirculation. This paper reports on a laser Doppler perfusion imaging technique based on dynamic light scattering in tissue. When a laser beam sequentially scans the tissue (maximal area approximately 12 cm *12 cm), moving blood cells generate Doppler components in the back-scattered light. A fraction of this light is detected by a remote photodiode and converted into an electrical signal. In the signal processor, a signal proportional to the tissue perfusion at each measurement point is calculated and stored. When the scanning procedure is completed, the system generates a color-coded perfusion image on a monitor. A perfusion image is typically built up of data from 4,096 measurement sites, recorded during a time period of 4 min. This image has a spatial resolution of about 2 mm * 2 mm. A theory for the system inherent amplification factor dependence on the distance between individual measurement points and detector is proposed and correction measures are presented. The performance of the laser Doppler perfusion imager was evaluated using a flow simulator. The correlation coefficient between the estimated flow parameter and the perfusion through a mechanical flow simulator was calculated to r = 0.996. To assess the sampling depth of the laser beam, light scattering in tissue was simulated by a Monte Carlo technique. The average sampling depth for skin tissue was calculated to 200-240 microns, depending on the blood content.(ABSTRACT TRUNCATED AT 250 WORDS)
组织灌注成像对于评估外周血管疾病对微循环的影响至关重要。本文报道了一种基于组织中动态光散射的激光多普勒灌注成像技术。当激光束依次扫描组织（最大面积约12厘米×12厘米）时，移动的血细胞会在背向散射光中产生多普勒分量。这部分光的一部分由远程光电二极管检测并转换为电信号。在信号处理器中，计算并存储与每个测量点处的组织灌注成比例的信号。扫描过程完成后，系统会在监视器上生成彩色编码的灌注图像。灌注图像通常由在4分钟时间段内记录的4096个测量点的数据组成。该图像的空间分辨率约为2毫米×2毫米。提出了系统固有放大因子与各个测量点和探测器之间距离的依赖关系理论，并给出了校正措施。使用流动模拟器评估了激光多普勒灌注成像仪的性能。计算得出估计的流量参数与通过机械流动模拟器的灌注之间的相关系数r = 0.996。为了评估激光束的采样深度，通过蒙特卡罗技术模拟了组织中的光散射。根据血液含量，皮肤组织的平均采样深度计算为200 - 240微米。（摘要截短于250字）
