Optical imaging and tomography for biomedical and clinical applications

Abstract

In recent years, optical imaging has been of significant interest as a non-invasive medical imaging modality for biomedical and clinical applications. Visible and near-infrared light wavelengths have been used for tissue and organ imaging using surface reflectance, transillumination and transmission based methods. Fluorescence optical imaging has shown great potential in molecular imaging with a spectrum of applications including drug discovery. Fluorescence imaging uses ultraviolet light to excite fluorophores and collects emitted light at a higher wavelength. Fluorophores include endogenous and exogenous fluorophores. The former refers to natural fluorophores such amino acid and structural proteins that are distributed in the tissue. The latter usually refers to some polymer nano-particles targeting at specific molecules such as hemoglobin. Recently, fluorescence tomography methods have been developed for investigations for tissue or animal imaging. The fluorescence tomography imaging methods conduct three-dimensional reconstruction of fluorescence bio-distribution in the object with respect to optical heterogeneity and fluorophores. The Optical Coherent Tomography (OCT) makes use of the coherent properties of light in the tissue medium for three-dimensional reconstruction. In an OCT system, light with a low coherence length is divided into two parts. One serves as reference while the other is directed into the tissue. When light travels in the tissue, it encounters mediums with different refractive indices providing partial reflections from the internal structures. The partial reflectance is compared with the reference signal for coherence. The OCT is based on low-coherence interferometry for obtaining sub-surface images at near-microscopic resolution extended to tissue reconstruction. In this talk, recent methods in optical imaging, fluorescence imaging, optical spectroscopy, and optical coherent tomography will be discussed with applications in clinical and therapeutic applications. Optical imaging methods for characterization of skin-lesions for early detection of skin-cancer will also be discussed using multispectral optical transillumination imaging methods.