Varghese Babu, Rajan Vinayakrishnan, Van Leeuwen Ton G, Steenbergen Wiendelt
MIRA Institute for Biomedical Technology and Technical Medicine, Biophysical Engineering Group, University of Twente, PO Box 217, NL-7500AE Enschede, The Netherlands.
Opt Express. 2010 Feb 1;18(3):2849-57. doi: 10.1364/OE.18.002849.
Perfusion measurements using conventional laser Doppler techniques are affected by the variations in tissue optical properties. Differences in absorption and scattering will induce different path lengths and consequently will alter the probability that a Doppler shift will occur. In this study, the fraction of Doppler shifted photons and the Doppler broadening of a dynamic medium, are measured with a phase modulated low coherence Mach-Zehnder interferometer. Path length-resolved dynamic light scattering measurements are performed in various media having a constant concentration of dynamic particles inside a static matrix with different scattering properties and the results are compared with a conventional laser Doppler technique, with a simple model and with Monte Carlo simulations. We demonstrate that, for larger optical path lengths, the scattering coefficient of the static matrix in which the moving particles are embedded have a small to minimal effect on the measured fraction of Doppler shifted photons and on the measured average Doppler frequency of the Doppler shifted light. This approach has potential applications in measuring perfusion independent of the influence of optical properties in the static tissue matrix.
使用传统激光多普勒技术进行的灌注测量会受到组织光学特性变化的影响。吸收和散射的差异会导致不同的光程长度，从而改变发生多普勒频移的概率。在本研究中，使用相位调制低相干马赫-曾德尔干涉仪测量动态介质中多普勒频移光子的比例和多普勒展宽。在具有不同散射特性的静态基质内含有恒定浓度动态粒子的各种介质中进行光程分辨动态光散射测量，并将结果与传统激光多普勒技术、简单模型和蒙特卡罗模拟进行比较。我们证明，对于较大的光程长度，嵌入移动粒子的静态基质的散射系数对测量的多普勒频移光子比例和测量的多普勒频移光的平均多普勒频率影响很小甚至最小。这种方法在测量灌注方面具有潜在应用，可不受静态组织基质中光学特性的影响。
