High-resolution photoacoustic tomography

Optical contrast is sensitive to physiological parameters, such as the oxygen saturation and total concentration of hemoglobin, in biological tissues. Photoacoustic tomography is based on the high optical contrast yet utilizing the high ultrasonic resolution. Our work in this emerging area of research will be summarized in this invited talk. In this technology, a diffraction-based inverse-source problem is solved in the image reconstruction, for which we developed the rigorous reconstruction theory. We implemented a prototype and accomplished non-invasive transdermal and transcranial functional imaging of small-animal brains in vivo. Changes in the cerebral blood oxygenation and blood volume of a rat, as a result of the alternation from hyperoxia to hypoxia, were imaged successfully.