Diffuse correlation spectroscopy for non-invasive blood flow measurement.

• Main Author: Toh, Hui Jin.
• Other Authors: Lee Kijoon
• Format: Final Year Project
• Language: English
• Published: 2011
• Subjects: DRNTU::Science::Chemistry::Biochemistry::Spectroscopy
• Online Access: http://hdl.handle.net/10356/45668
• Institution: Nanyang Technological University

Diffuse Correlation Spectroscopy (DCS) is a novel promising technique which adopts the diffusive nature of light propagation in resolving motions of scatterers in the turbid media to initiate non-invasive in-vivo analysis of blood flow. Unlike conventional non-invasive methods, DCS does not involve external contrast agents usage and radiation dose concerns. In addition, DCS has a distinguishing feature of probing deep tissues with high resolution, given its high sensitivity to minute displacements in biological samples. This proficiency makes adequate information about capillary blood flow achievable in the fields of mammography[1]. Hence, the advantage of having high contrast resolutions enables diverse applications of DCS, especially in medical diagnostics such as medical imaging[2-3]. In this report, the author presents the design, analysis and implementation of the point-source-point-detector DCS system in optically monitoring relative changes of non-invasive flow. Preliminary experiments were conducted on a phantom with known optical and dynamical properties to permit a more quantitative understanding of the DCS signal from actual tissues. After which, applications of DCS that involve measuring in-vivo blood flow responses during cuff inflation and deflation, and blood flow in rat tumor model throughout the Photodynamic Therapy (PDT) were elaborated. Experimental validation of DCS proposes a sound coupling of the DCS signal to blood flow. The mean square displacement as a result of both Brownian diffusion and random flow was determined. While the scattered motion of blood cells is not considered to be Brownian in living tissue, the autocorrelation functions are generally better characterized with diffusion than with random flow. Experimental results were in logical agreement with the data from literature, thereby offering an opportunity for real-time blood flow monitoring in clinical applications.