Muyinatu Bell, Ph.D., known informally as “Bisi,” is a mid-career scientist at Johns Hopkins University (JHU) who is recognized for her innovations that have improved the quality of ultrasound and photoacoustic imaging.
Guided by the philosophy that innovation lies at the intersection of disciplinary boundaries, Bell leads a research program that integrates optics, acoustics, robotics, electronics, and mechanics, as well as signal processing and medical device design.
In addition to directing the Photoacoustic and Ultrasonic Systems Engineering (PULSE) Lab at JHU, Bell is the John C. Malone Associate Professor of Electrical and Computer Engineering, Biomedical Engineering, and Computer Science, and is affiliated with the department of oncology.
Bell wants to ensure that imaging tools are highly effective for everyone regardless of their body size or skin color. She has drawn attention to the fact that some breast imaging methods don’t perform as well among women with darker skin tones.
One of her major research contributions has been the development of a beamforming technique called short-lag spatial coherence (SLSC) that can remove noisy background information (acoustic clutter) in ultrasound images.
A recent study she led investigated how skin tone affects the visibility of breast cancer targets in photoacoustic imaging. The results showed that breast models with darker skin tones have more acoustic clutter than those with lighter skin tones, which can make it harder to detect breast cancer.
Budding scientist turned engineer
Bell knew from age six that she wanted to be a scientist. “At first, it was just the idea of wearing a lab coat and doing experiments that looked cool. That morphed into trying out experiments at home using science books I checked out from the public library, competing in annual science fairs at my school, and becoming a chemistry major in high school,” she said. Bell learned about biomedical engineering in high school when she participated in a program for sophomores who excelled in STEM.
As an undergraduate student at the Massachusetts Institute of Technology (MIT), she minored in biomedical engineering and majored in mechanical engineering because MIT lacked a major in biomedical engineering at the time, Bell said. When she switched to Duke University for graduate school, she pursued a Ph.D. in biomedical engineering.
Shaping her imaging career
During her first year at Duke University, Bell participated in the NIH Medical Imaging Training program, which she says helped to shape her medical imaging career. The program provided rigorous training in a variety of diagnostic imaging technologies, including ultrasound.
“I was attracted to ultrasound imaging, especially its potential to detect cancer based on distinguishing stiff tumors from surrounding healthy soft tissue. In addition, ultrasound is portable and inexpensive compared to other imaging modalities, which could have an impact in different communities throughout the world,” said Bell.
As a graduate research assistant at Duke University from 2006 to 2012, Bell investigated sources of acoustic clutter in ultrasound imaging, which led to new methods of reducing acoustic clutter such as the SLSC beamformer, which she tested in phantoms, simulations, and clinical cardiac data from human patients.
Upon receiving her doctoral degree, Bell pursued a postdoctoral fellowship at the Johns Hopkins Engineering Research Center for Computer-Integrated Surgical Systems and Technology. There, her research projects expanded to photoacoustic-guided neurosurgery, robot-assisted ultrasound-guided radiation therapy, and photoacoustic imaging of tiny radioactive seeds in the prostate used to treat prostate cancer.
At the end of her graduate school career, Bell aspired to be an independent researcher. Receiving the NIH/NIBIB K99/R00 Pathway to Independence Award enabled her to transition from a mentored research position to an independent researcher as a tenure-track academic. Bell became an assistant professor at JHU in 2017 and founded the PULSE research lab the same year.
Bell has received NIBIB funding for her biomedical imaging research projects since 2015. An NIBIB Trailblazer Award in 2018 enabled the PULSE Lab to develop machine learning software that trains computers to remove acoustic clutter from ultrasound images so interventional radiologists can see only the structures they’re interested in, such as a needle tip or a tumor.
Bell used the multi-year NIBIB support to develop a sophisticated imaging system that’s used for research pending further clinical development. The new imaging system allows blood vessels hidden behind bones to be seen during surgery to remove pituitary tumors, which will help avoid injuring the carotid arteries.
Rewards, challenges, and lessons learned
Bell enjoys being an academic researcher, especially at this stage of her career, where she can run her own lab and has the independence and freedom to work on problems that interest her. She also enjoys giving back to the field by supervising and mentoring new groups of Ph.D. students and early-stage researchers.
“The most rewarding aspects of my work are seeing the real-world impact of what we do and interacting with patients, physicians, friends, and family who are inspired by various aspects of my research contributions, such as my work addressing the impact of skin tone in photoacoustic imaging,” said Bell.
She also teaches, writes grant applications and research papers, and serves on committees. Bell recognized early in her career that she couldn’t do everything and learned to set priorities.
“Now, the most challenging aspects of my job are trying to convince others to care about the same passions that I have, and to accept and move on when our interests don’t align,” said Bell.
Her advice to women interested in biomedical engineering/imaging research careers is “go for it. It won’t always be easy, but as long as you set your priorities and are satisfied with the outcomes, that’s more important than any associated doubts you have.”
When she’s not working, Bell likes to travel, go to the beach, connect with friends and family over a good meal, sing karaoke, relax, and exercise.