Photo of Lei Li

Biotechnology & medicine

Lei Li

Understanding the human brain through photoacoustic tomography

Year Honored


Li Lei started his master's degree in 2012 and got his Ph.D. at the California Institute of Technology in 2019. During this period, Li Lei dedicated himself to biomedical imaging and achieved many accomplishments. So far, he has published 9 high-impact papers in top journals (6 first-authored, 7 have been published, and 2 have been accepted for publication), 4 in high-level journals (3 first-authored), 19 in optical journals (5 first-authored), and 9 in international conferences (5 first-authored). He applied for 4 US patents and was also invited to deliver keynote presentations on photoacoustic tomography at the National Institute of Standards and Technology and the National Institutes of Health.

Now he continues his postdoctoral research in Prof. Wang Lihong's, a member of the National Academy of Engineering, laboratory at the California Institute of Technology.

Li Lei has been working on cutting-edge imaging fields. He has developed the most advanced photoacoustic computed tomography system, named single-impulse panoramic photoacoustic computed tomography. He demonstrated the structural and functional imaging of the whole brain in rats and revealed the resting-state functional connectivity of the whole brain. This is beyond the reach of existing optical imaging techniques and provides a powerful tool for further study of neural activity in the deep brain and the whole brain.

Li Lei combined the photoswitchable phytochrome probes to photoacoustic tomography. He used near-infrared light to switch the photosensitive protein on and off. By taking images at both the on and off states, the photosensitive proteins will be selectively imaged at a very high contrast through differential imaging of the two states. It achieved ultrahigh detection sensitivity, high contrast, and multiscale imaging for the first time.

Li Lei also proposed a new decay characteristic analysis method, which can realize accurate quantitative multi-contrast imaging in the deep tissue of the living body. At the same time, the combination of the advanced photoswitchable probes and photoacoustic computed tomography has, for the first time, achieved real-time high-resolution imaging of protein-protein interactions in deep tissue. This technical advancement paves a new avenue for cancer study and drug development.

Li Lei's third academic contribution is that he has introduced the concept of ergodicity into photoacoustic imaging and realized snapshot widefield high-throughput imaging. This technique captures wide-field images with single laser shots by encoding spatial information with randomized temporal signatures through the ergodic cavity. This ergodic cavity based photoacoustic imaging system can be easily miniaturized toward wearable applications for tumor detection and human vital sign monitoring.