M.Sc Thesis

M.Sc StudentAkons Kfir
SubjectImage-Guided Optical Measurement of Blood Oxygen Saturation
and Hemoglobin Concentration along Capillary
DepartmentDepartment of Biomedical Engineering
Supervisor ASSOCIATE PROF. Dvir Yelin
Full Thesis textFull thesis text - English Version


Oxygen is supplied to the body tissues through the blood circulation, carried by the hemoglobin protein in the red blood cells. Knowledge of the oxygen levels within the blood and tissue is valuable for assessing heart and lung function, as well as for measuring local tissue viability, and is commonly performed using invasive catheters and blood sampling. Non-invasive measurement of oxygen saturation, which is mostly desired for routine clinical care, often rely on the unique optical absorption spectra of hemoglobin. Because of the high scattering of light by tissue, most measurements probe relatively large tissue regions, averaging over multiple blood vessels and concentrating mainly on either arterial or venous oxygenation. Measuring oxygen saturation in capillary vessels could provide valuable information on oxygen transport and tissue viability in small regions of interest; however, the low spatial resolution of most spectroscopic techniques fail to account for the small vessel dimensions and the steep gradients of oxygen saturation levels. This thesis describes a non-invasive technique for image-guided confocal measurement of the optical absorption spectrum from a small volume that is comparable in size to the cross section of a capillary vessel. A large variability of oxygen saturation levels in a single capillary vessel was demonstrated, with significant oxygen loss rates of approximately 7.1% per 100 μm. The presented technique could help in studying oxygen exchange dynamics in tissues and could play a future role in clinical diagnosis and therapeutic applications that require localized tissue inspection.