Biomedical Engineering seminar: Photoacoustic imaging and focusing in deep biological tissue

The Department of Biomedical Engineering Seminar;
Lidai Wang, Ph.D., Department of Biomedical Engineering, Washington University in St. Louis

Date: Thursday, January 29 – 1:00 pm, Room: 320 Dillman

Title: “Photoacoustic imaging and focusing in deep biological tissue”

Taking advantage of rich molecular contrasts and safe non-ionizing radiation, optical imaging has been playing increasingly important roles in biomedical applications. However, a fundamental limit of
optical imaging in biological tissue is light diffusion, which prohibits high-resolution imaging at depths beyond ~1mm. To break through this limit, we recently developed photoacoustic imaging and wavefront shaping technologies for in vivo functional imaging, early cancer detection, and focusing light into diffusive regimes. This presentation will first discuss the development of video-rate functional photoacoustic microscopy which, for the first time, enabled real-time quantitative imaging of oxygen release from single red blood cells in living tissue. Then I will introduce another functional photoacoustic imaging modality, ultrasonic-encoded photoacoustic flowgraphy, which can measure extremely slow blood flow in deep tissue with four times higher sensitivity than ultrasonic Doppler flowmetry. In addition, I will present a novel technique named nonlinear photoacoustic guided wavefront shaping (PAWS) that enables diffraction-limited optical focusing and imaging in highly scattering media such as deep biological tissue.