Speckle-based measurement of the light scattering by red blood cells in vivo

Abstract

Optical spectroscopy approach, using non-coherent light sources, has become an important tool for non-invasive analysis in vivo. It is based on the assumption that biochemical characteristics of biological system can be determined through the optical coefficients of blood and tissue particles. Thus, in the framework of this approach, the major concern is to express the obtained optical signals in terms the optical coefficients of the single particle of blood or tissue. However, since the light propagation in tissue is dominated by the multiple-scattering component, a direct measurement of single scattering characteristics turns to be a very difficult task. Practically, only the relative changes of absorption and scattering coefficients are measured. We suggested to adopt the dynamic light scattering (DLS) or speckle technique for the determination of the light scattering coefficients of the red blood cells under stasis conditions in vivo. We assumed that under zero flow conditions the RBC movement is driven mostly by the Brownian motion. It was shown, that under appropriate measurement geometry, the measured optical signal can be decomposed into a few major components. The most dominant components are ascribed to the single backscattering and forward scattering coefficients of the red blood cells. In-vitro and in vivo experimental tests have shown a good correspondence between the theoretically estimated and experientially measured results. The obtained results indicate that the DLS technique can be adopted for the determination of blood particles scattering characteristics in addition to the movement and effective viscosity parameters measurement in vivo.

Postoperative Hemodynamic Index Measurement With Miniaturized Dynamic Light Scattering Predicts Colorectal Anastomotic Healing

“…The DLS system has been developed for decades for various clinical indications. 15,32 The device in our study has been previously tested in human subjects at different clinical conditions for assessment of capillary skin flow, RBC-endothelial interaction, and pulse wave hemodynamic characteristics. 32 We analyzed the data with a frequency between 1 and 5 kHz in the current study, which is considered to best represent tissue perfusion.…”

“…15,32 The device in our study has been previously tested in human subjects at different clinical conditions for assessment of capillary skin flow, RBC-endothelial interaction, and pulse wave hemodynamic characteristics. 32 We analyzed the data with a frequency between 1 and 5 kHz in the current study, which is considered to best represent tissue perfusion. 16,17 Substantial data can be further extracted to investigate the microcirculation with other characteristics.…”

New noninvasive index for evaluation of the vascular age of healthy and sick people

“…4,5 In our previous studies [6][7][8] we measured intravascular mobility of RBC as a natural marker of the effective viscosity of the blood plasma in close proximity to the vascular wall. For this end, we utilized DLS 9 for measurement of the RBC diffusion coefficient under the condition of intermittent stasis.…”