Throwing fresh light on optical tomography imaging

20 May 2020

After excelling in physics and mathematics at his high school, Renjie Zhou (Croucher Innovation Award 2019) headed for university in Wuhan in China where he aimed to focus on pure science, to understand photons, the fundamental unit of light, “for my own sake”.

Sixteen years on, after nine years of research and study at American universities, Zhou has more altruistic goals. Now an Assistant Professor in the Department of Biomedical Engineering at the Chinese University of Hong Kong (CUHK), his direction has moved toward practical applications in material science, biology, medical diagnostics, and treatment.

At CUHK, where he joined the Faculty of Engineering in May 2017, two months before the establishment of the Department of Biomedical Engineering, Zhou’s research focus is on building biomedical imaging instruments. He has compared his laboratory to a hardware store providing the research tools for biologists, doctors, and scientists. His research teams are heavily involved in collaborations, including with doctors at the Prince of Wales Hospital, a public hospital in Shatin in Hong Kong, testing applications of the imaging instruments they develop.

One of Zhou’s main research focuses is on developing an optical tomographic imaging technique, with further exploration now being supported by his five-year Croucher Innovation Award. His goal is to implement this for non-invasive imaging on humans for clinical applications, he explained.

He has two separate research teams working on optical tomographic imaging, one concentrating on developing a fast, powerful 3D microscope, known as a high throughput tomographic phase microscope, to image millions of cells within a short time. Such an instrument will enable, for example, identification of rare cancer cells in blood, delivering diagnostic results in minutes.

“Hopefully, that can eventually be something that can be put into clinical settings in hospitals,” he said. “We are building the first working system. We are thinking about making the system simpler and cheaper, then more people will benefit from it. We can even commercialise it.” This may be possible within three to five years, he said.

His other team is working on in vivo 3D optical imaging – that is, imaging inside a living organism such as a human body. With very high imaging resolution, their equipment can see cells and tissues, with the aim of detecting cancer or other diseases at the earliest stage. Conventional 3D imaging techniques, such as MRI and CT scans, do have the resolution to see individual cells. However, as cancers develop from cell or even sub-cellular level, high resolution imaging modality could enable early stage detection and intervention.

For Zhou, it is satisfying and exciting work. “At the moment with optical imaging, there are very few techniques that can be implemented for clinical applications on humans. This is one of the first that can be implemented with this high resolution.”

His laboratory is based behind blackout curtains , which is ironic given his explanation for his career choice: “When I was young, I was always fascinated by the mystery of light.” Discussions about light’s properties and composition in high school physics amazed him.

“I really wanted to understand what was happening and I found that a lot of technologies are based on using light – communication, imaging, quantum mechanics, for example,” he said. Studying in the manufacturing hub of Wuhan, “the capital of optics” with a designated high-tech Optics Valley, made this possible.

As a postgraduate at the University of Arizona, Zhou discovered its College of Optical Sciences (now James C Wyant College of Optical Sciences) had more than 100 faculty members working on optics and more than 100 optics-related courses. A course in optical imaging and his realisation of its potential – for example, for biomedicine – set him on his current path.

Initially, Zhou’s work was largely theoretical. “I was first involved in theoretical modelling. I tried to model images, to model physics,” he said. “Gradually, I found that if you do something, you really want to make it practical so people can benefit from it. When I went to Illinois for my PhD study, I wanted to focus more on using my knowledge in optics to develop imaging techniques for practical applications.”

That work, where he developed a theoretical foundation for a new 3D cell imaging technique, formed the basis of his co-first authored paper in the prestigious journal, Nature Photonics, in 2014.

Through that 3D cell imaging project, he also began building instruments. Initially that involved upgrading a conventional microscope to enable the construction of 3D images of live cells in a non-invasive manner – work on which he is building today.

Deciding to pursue it in more depth, he moved to MIT, Boston, to undertake postdoctoral research. There, in the underground George R Harrison Spectroscopy Lab, devoid of ambient light and vibration that could have interfered with his work, he undertook research that formed the foundations of his Croucher Innovation Award project. “I worked on building more instruments and trying to enhance the performance of those instruments. In MIT I was more focused on constructing the imaging instruments.”

Publishing as first author on this work in Optics Express in 2017, Zhou and his MIT team noted the potential of developing a tomographic phase microscope. In a 2017 review article in the Journal of the Optical Society of America as co-first-author, he and his colleagues predicted that this imaging technique could one day become popular with physicians and scientists around the world.

They also noted the urgent need for the development of high throughput and in vivo imaging methods – the fields in which Zhou and his teams are now attempting breakthroughs with potential to revolutionise blood screening, diagnostic and treatment capabilities not only for cancer but also for the detection of eye and other diseases.

Renjie Zhou is an Assistant Professor in the Department of Biomedical Engineering, Chinese University of Hong Kong (CUHK). He obtained his Bachelor degree at Huazhong University of Science and Technology in Wuhan, China, before undertaking Master’s research in optical sciences at the University of Dayton and University of Arizona, in the US. He completed his PhD at the University of Illinois at Urbana-Champaign, also in the US. After undertaking postdoctoral research at MIT in Boston, he joined CUHK in 2017.

To visit Zhou’s Croucher profile, please click here.