For cancer patients, imaging technologies such as x-ray computed tomography (CT) and positron emission tomography (PET) are indispensable tools for diagnosis and treatment. Fourth-year UW Bioengineering Ph.D. student Efren Lee aims to advance these technologies to help physicians better plan and evaluate the success of individualized treatment, and to improve patient outcomes.
The two types of scans provide complementary information. CT scans offer anatomical information such as the size and shape of a tumor within the body, while PET scans offer detailed information about the biology of disorders at the molecular level. With a PET scan, a doctor can distinguish living or dead tissue, determine cellular activity and gain a detailed, quantitative perspective of how the tumor is responding to treatment.
However useful a PET scan is, its accuracy can be affected by a phenomenon called attenuation, or loss of detection. When CT and PET are used together, the CT scan can collect information for correcting the attenuation bias and errors in PET.
This collective power is compromised, however, if CT scan does not anatomically match the PET scan. In lung cancer patients, for example, a patient’s breathing patterns may be irregular or labored during a 30-second CT scan and the following 20-minute PET scan. CT scan data that accounts for different conditions causes the corresponded PET scan to be inaccurate.
With his lab, Efren is interested in solving this PET/CT mismatch problem. “PET/CT is becoming a gold standard,” he explains. “But as hardware keeps improving, there’s still a lot of room for improving the protocol.” His lab discovered that lengthening the CT scan time allows for more detailed data to correct for attenuation bias in the following PET scan. “If they have a good match, the quantitative information for PET will be more accurate.”
While extending the scan time, the research team aims to reduce the amount of radiation a patient is exposed to. Like traditional x-rays, CT scans expose patients to ionizing radiation. There is ongoing concern in the medical community about the effect of ongoing exposure to radiation in patients who receive CT scans. “We know that by extending the scan time, we can increase the accuracy,” Efren explains. “But extending the scan time of CT will result in increased radiation dose. If we can lower the dose, how low can we go?”
To answer this question, Efren is developing methods for analyzing statistical data that he hopes will lead to an ultra-low dose image reconstruction algorithm for PET/CT scanners. Current PET/CT scanners are programmed to account for a standard radiation dose, and are inaccurate when used to compile data from an ultra-low dose CT scan. “There’s no protocol for this,” Efren explains. “If I can apply the knowledge I’ve gained through this research, we can come up with the ultra-low dose algorithm.”
Research in an interdisciplinary culture of collaboration, support
An international student from Taiwan, Efren started out studying chemistry. Eventually, however, he realized he wanted to pursue clinical applications of science. He was especially interested in imaging — and was particularly inspired by Albert Einstein’s equation E=mc2. “I knew this was the most famous equation in science since I was a child, but I thought it was so distant from me,” he explains. “However, I realized that exactly depicts what has happened in PET imaging.” Efren was excited by the prospect of applying what he saw as one of the highest achievements in science findings to daily clinical practice.
After serving one year of military service in Taiwan, Efren moved to the U.S. and completed a master’s in biomedical imaging at the University of California San Francisco. He planned to focus on optical imaging, but wanted to get closer still to applying his work to clinical care. “Optical imaging is a powerful approach in basic science research,” he says. “I found that CT, MRI, ultrasound, PET and SPECT are closer to the patient.”
He decided to change his focus to nuclear medicine, and chose to attend UW on the basis of its strength in imaging research. He works with Paul Kinahan, UW professor of radiology and adjunct faculty in bioengineering, in the Imaging Research Laboratory. The lab collaborates with clinical, academic and industrial partners to advance imaging technology and translate research to clinical applications that improve health care.
Efren was drawn to the idea of working in an interdisciplinary lab, and now sees it as a good environment for his Ph.D. research. “We have faculty who focus on algorithms and statistics. Some are more focused on hardware. Two are in radiation oncology, and focused on clinical care,” he explains. Beyond his lab, he also appreciated UW’s culture of collaboration, especially at UW Medical Center. “If I need to borrow a PET/CT scanner for my work, I can do it today. I feel that UWMC is very supportive of graduate student research.”
He also appreciates BioE’s dedication to the graduate student experience. He had the opportunity to serve on the department’s curriculum committee for two years, which offered him a unique perspective of how the department supports students through its strong curriculum and focus on training interdisciplinary researchers. “I can feel that the department really cares about the students.”
A path to industry, frontier of medical imaging
Efren plans to pursue a career in industry after completing his Ph.D. He says that BioE’s BioEngage industry relations program has been a useful resource for himself and students who want to follow similar career paths, as opposed to careers in academia. “Through BioEngage, I feel that the department really supports the choice of students to go into industry.”
He also says BioE’s community of alumni in industry helps students who wish to gain industry experience. Last summer, he completed a summer internship at Toshiba Medical Research Institute, an opportunity that became available through a former BioE Ph.D. student. “Her company had an opening and they really wanted a student from UW BioE,” he explains. The alumnus reached out to Dr. Kinahan, who recommended Efren for the position. “We have a lot of outstanding alumni, and I think this is a very precious asset to BioE students.”
Through his internship, Efren became even more confident in his decision to pursue a career in industry. “I want to go to the frontier of the medical imaging business, to see what the problems are with daily clinical practice.” From his perspective, industry research moves quickly to devise solutions to problem. “I love the fast pace, and I really think that side of research is closer to the patient.”