Biomedical Applications of Diffuse Reflectance Spectroscopy and Hyperspectral Imaging

Abstract

Optical measurement techniques have a large potential as diagnostic tools in medicine. This thesis covers multiple biomedical applications of optical spectroscopy and hyperspectral imaging. Main topics have been monitoring of photodynamic therapy of bladder cancer, age determination of bruises for forensic applications, and tissue characterization, including hyperspectral characterization of atherosclerotic plaques.

Diffuse reflectance spectroscopy was found to be a suitable modality to monitor skin reactions following non-penetrating trauma, and may be a candidate to accurately and objectively determine the age of such bruises, a large improvement over current age determination methods. Hyperspectral imaging is another candidate for this purpose, a large advantage being that it records the entire scene and thereby allows both the spectral and spatial development of the injury to be monitored. The combination of hyperspectral imaging, statistical image analysis and diffusion modeling was proved to be a versatile and powerful tool for characterization of bruised skin and vascular structures (e. g. blood perfusion). The results show that these tools can be used to derive information about the depth and structure of the vasculature. The combination of reflectance and fluorescence hyperspectral imaging has also been demonstrated in characterization of atherosclerotic lesions, where hyperspectral imaging and image analysis were shown to identify the complexity and large heterogeneity of such plaques as compared to histology