A Track Record of ‘Lightbulb Moments’
What drew you to photonics?
Growing up in India, I'd always wanted to go into medicine but missed the required grades by one point. I didn't know what to do next but I was really good at physics, so pursued an undergraduate degree in physics and mathematics at the University of Bombay-Mumbai with an attitude of not wanting to be there. Then I met Professor S. B. Patel, my Nuclear and Laser Physics Professor and lifelong mentor, who suggested that I should consider bringing physics and medicine together. He introduced me to biomedical engineering and optics, and turned my professional life around.
When did you first encounter spectroscopy?
I moved to the University of Texas-Austin to do a PhD and found Professor Rebecca Richards-Kortum. She introduced me to optical spectroscopy and its application for the diagnosis of cervical pre-cancer. While I started with fluorescence spectroscopy, I quickly became convinced this might not be the answer to solve this problem, and switched to Raman spectroscopy. I soon discovered that signals from the optical fibers interfered with tissue measurements, so designed a novel probe that could filter these spurious signals and detect tissue. Each measurement took 90 seconds instead of today's two seconds, but building a system that could collect Raman signals in vivo was the highlight of my PhD and convinced me to continue this area of research.
At Vanderbilt you translate optical technologies into diagnostic tools — tell us more.
I develop all kinds of spectroscopies and imaging but what I do is different to many people — my research is problem-based and I focus on medical problems. We need people to develop new light-based technologies such as photoacoustics or optical coherence tomography but we also need people to match the problem to the solution. My approach is to understand the problem and find the best technique to solve it.
Examples of your problem-led approach?
Just over a decade ago, a third-year surgical resident [at Vanderbilt] explained that finding the parathyroid glands, an organ that regulates the calcium in your body, during neck surgeries is difficult, and asked if there was a light-based solution. We discovered that there is a very strong near-infrared auto-fluorescence signal in parathyroid tissues compared to all other tissues in the neck. This discovery led to the development of the ‘PTeye,' an approach to help the surgeons confirm the identity of the parathyroid gland during surgery. At the time, most researchers were looking at disease detection using light but we were focused on finding an organ. PTeye is now FDA-approved and is one example of something that I always hoped to accomplish — to take something from the bench all the way to patient care.
Anita Mahadevan-Jansen with students. Credit: Vanderbilt University.
You have used Raman spectroscopy to assess breast cancer margins and detect inflammatory bowel disease, early throat cancers and more. Will we see FDA-approved devices soon?
With the parathyroid glands, the fluorescence signal is so clear and doesn't require a lot of fancy processing — this made a huge difference to patient-numbers in trials and allowed us to get PTeye through FDA quickly. But with Raman spectroscopy you are looking at subtle changes in signals, and need to use multivariate statistics using data from many more patients, so approval takes longer. However, it is a powerful technique and for the right application, the right solution. For example, we're using the technique to evaluate the cervix as it re-models during pregnancy to predict the risk of pre-term labor and birth.
Your research on infrared neural stimulation (INS) is a little different — why do this?
This is one project where my husband, Dr. Duco Jansen, and I work together. We were sharing a bottle of wine with a neurosurgeon friend, when we wondered if it would be possible to stimulate neural activity. The next day, we went to the lab and applied Vanderbilt's Free Electron Laser (FEL) to a frog sciatic nerve. Low and behold, for every pulse, we saw a twitch that we could record. We've since applied this to the peripheral and central nervous system of sea slugs, rodents, primates and humans, and even single cells.
Will we see INS in clinics soon?
We have demonstrated the safe use of INS in cerebral palsy patients. These patients have an uncontrollable tremor — to help this, a few rootlets can be cut using electrical stimulation, but deciding which rootlets to cut is an educated guess. However, with INS we see which muscle group is innervated by that rootlet, and can accurately decide which to cut. We can also use the method for monitoring nerves during, say, cancer surgery, and hope to trial this on patients in a couple of years.
This is your 28th Photonics West. Can you explain why this conference is so important?
I attended my first Photonics West as a 2nd year PhD student in 1992. The conference showed me the breadth and depth of what light can do, and the networking was invaluable. I have since attended every meeting except one, and my husband is also a biophotonics researcher, so we come to this conference together each year. Even when I had my daughter, we were at the conference 3.5 weeks later with her in tow. In fact, my daughter had attended ten shows by the time she was ten years old. This was in an era when people didn't bring their kids to conferences, but SPIE was supportive and helped us handle that work-life balance. Photonics West really brought both parts of my world together and holds a very special place in my heart.
This year you will serve as VP of SPIE and become President in 2022 — what are your hopes?
My research allows me to identify and understand a problem and bring the right solution to it — I'm hoping to bring that skill to the SPIE community. I want to listen to our members and help develop solutions and help them make connections. I would like to provide a global voice and showcase the benefits of being part of SPIE so more people can take advantage of its resources. I will of course, continue my efforts in bringing equity, diversity and inclusion to all aspects of SPIE and the optics and photonics community.
Advice to other researchers?
Interdisciplinarity is directly responsible for my success, but so is making connections with people and accepting help. When I arrived at Vanderbilt I was six months pregnant so spent the first few months at home. The then Department Chair, Professor Tom Harris, liked what I did, so said ‘whenever you want to start, you can come in and I will support you'. If it wasn't for mentors like him and Dr. Patel who guided me along the way, it would have been difficult to achieve everything that I have done. Seek the mentors and role models — SPIE is a huge resource here. Don't feel bad about asking for help — people often feel they have to achieve everything alone — I don't think that's necessary. This meeting is the perfect place to make connections that will last a lifetime.
Rebecca Pool is a UK-based freelance writer. This article originally appeared in the 2020 SPIE Photonics West Show Daily.
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