报告内容摘要（Abstract）

By physically combining electromagnetic and ultrasonic waves, photoacoustic imaging (PAI) has proven powerful for in vivo early-cancer detection and functional or molecular imaging. In PAI, a pulsed laser beam illuminates the biological tissue to generate a small but rapid temperature rise, which leads to emission of ultrasonic waves due to thermoelastic expansion. The short-wavelength ultrasonic waves are detected outside the tissue by an ultrasonic transducer or transducer array to form an image that maps the original optical energy deposition in the tissue.

The talk will focus on the recent progress of PAI on exciting new fronts. First, PAI has broken the optical-diffraction limit and achieved super-resolution (~80 nm) imaging by using non-linear photobleaching or photo-switching dynamics, extending its applications into sub-cellular nano-dimensions. Second, by using a novel pulse-width-based single wavelength method, ultra-fast photoacoustic microscopy has achieved a 1D oxygenation imaging rate of 100 kHz, allowing label-free imaging of mouse brain activity with high spatial–temporal resolution. Third, taking advantage of the newly developed far NIR non-fluorescent protein BphP1, which can be reversibly switched ON and OFF, PAI has achieved more than 200 times enhancement in detection sensitivity in reporter gene imaging, allowing early-stage cancer imaging at >7 mm in tissue with a detection sensitivity of ~40 cancer cells. This new technique can also dramatically enhance the spatial resolution of photoacoustic microscopy to the sub-diffraction level. 

报告人简介 (Biography)

Dr. Junjie Yao received his B.E. and M.E. degrees in Biomedical Engineering from Tsinghua University, Beijing, in 2006 and 2008, respectively, under the tutelage of Prof. Jing Bai. He received his Ph.D. degree in Biomedical Engineering at Washington University, St. Louis (WUSTL), in 2013, under the tutelage of Prof. Lihong V. Wang. He is currently a postdoctoral research associate at WUSTL.

Dr. Junjie Yao’s research interest is in novel photoacoustic, optical, and ultrasound imaging technologies in biomedicine. In the last six years, he has published more than 50 peer-reviewed journal articles and two book chapters. He (co-)invented photoacoustic Doppler-bandwidth flowmetry, photoacoustic oxygen metabolic microscopy, and photo-imprint super-resolution photoacoustic microscopy. In particular, his MEMS-based photoacoustic microscopy is currently the world’s fastest high-resolution photoacoustic imaging system. He received the 2012 Chinese Government Award for Outstanding Students Aboard.