Laser based signal and image fractal analysis for assessment of blood flow

Laser based techniques offer non invasive means of imaging and optical signal acquisition in the biomedical field. Laser Doppler flowmetry and laser speckle imaging are important laser based methods in current research and have been explored for the analysis of blood flow. Doppler flow meters as well as laser speckle imagers use tissue backscattered light to non-invasively assess the blood flow rate. While because of large spatial variability and the temporal heterogeneity in tissue microvasculature, the measured blood flow rate is expressed in relative units in laser Doppler, laser speckle methods offers a whole field imaging resulting in absolute measurements of flow velocity. Measurement of and analysis of blood flow is vital in evaluating normal as well as differently diseased conditions of the human body. Several parameters related to flow along with flow velocity are important in characterizing tissues based on blood flow. Complexity of the flow is one of such important parameters which could be explored by looking at the fractality of the acquired Doppler signals / speckle images. In this paper, we are comparing the results of blood flow complexities assessed through fractal dimensions of Doppler signals and speckle images acquired from different parts of the body. The method adopted is expected to serve as a helping tool in characterizing normal and malignant tissues with associated variation in blood flow complexities based on the values of obtained fractal dimensions in such cases. © 2012 SPIE.