The easily visualize metabolic pathways of cancer cells.

The imaging technology plays critical role in diagnosing numerous life-threatening diseases, such as
cancers, cardiovascular diseases, and neuro-disorders. I deeply fell in love with this field when I was a
freshman. Studying biomedical imaging at UC Davis soon became delightful and exciting. As I have
always been eager to discover secrets of life, and improve wellbeing of humans from an engineering
approach, I decided to pursue a lifelong career as a professor of biomedical engineering and imaging.
With this propelling motivation, I joined Dr. Angelique Louie laboratory in UC Davis two years ago to
work on projects associated with MRI and spectroscopy. I first worked with a postdoctoral fellow, Dr.
Garcia, to study MRI antioxidant biosensors and dual-modal probes. During the collective works, Dr.
Garcia has significantly trained me in forming hypothesis, designing experiments, exploring conditions,
and trouble-shooting. I enjoyed working and sharing ideas with him. My first independent project was
to design and characterize emission profile of fiber-coupled LEDs for photosensitive contrast agents.
Utilizing mathematical models, I found that single-wavelength UV irradiations at isomerization peaks
generates more significant MRI T1 relaxation changes than the traditional white light. Through failures
and attempts, I witnessed the essence of perseverance and motivation in research. Like the synthesis of
MRI probes, best results are usually obtained after a number of painstaking struggles and efforts.
While MRI is a powerful tool for diagnosis, it does have limitations. For example, contrast-enhanced
MRI scans cannot easily visualize metabolic pathways of cancer cells. In contrast, nuclear medicine
imaging tools, such as the PET scan, can efficiently monitor cellular metabolisms by tracking glucose
exchanges. With the great interest and curiosity in PET, I joined the laboratory of Dr. Simon Cherry in
fall 2016, who had been a leader in PET instrumentation research for years. I have worked on several
PET projects in his group. One of my independent projects is to optimize timing resolution of BGObased
detectors. While BGO is a common scintillator in the detector arrays of a TOF-PET, it usually
produces insufficient scintillation photons, limiting timing resolution of detectors and accuracy of PET
images. We hypothesized that under certain sampling conditions, capturing Cerenkov photons in BGO
crystals instead could be an improved method. After coupling BGOs with NUV-SiPM photodetectors,
I designed a computer program to down-sample SiPM signals and then discriminate Cerenkov photons.
I am very excited that an outstanding 500ps timing resolution can be achieved by this novel method.
Biomedical engineering research integrates the expertise of both biomedicine and engineering. Without
a thorough understanding of the cancer biology, for instance, it is difficult for engineers to design the
elegant tumor-specific imaging techniques for accurate diagnosis. To enrich my research experience in
cancer biology, I obtained a summer research opportunity in Dr. Yan Liu laboratory at the Indiana
University School of Medicine, to focus on tumor suppressor p53 and leukemia. I worked with a Ph.D.
student, Sisi Chen, to study the role of p53 target gene Necdin during the response of human leukemia
cells towards chemotherapy treatments. I found that human leukemia cells could be sensitized by the
loss of Necdin. Furthermore, when expressing mutant p53, hematopoietic stem cells (HSCs) are also
resistant to chemotherapy-induced cell deaths. In summer 2016, I worked in Dr. Yunlong Liu group to
study bioinformatics at the same school. Dr. Yan Liu and Dr. Yunlong Liu have been collaborating on
the p53 project for the past several years. From analysis of the genome wide data of microarray, RNAseq,
and ChIP-seq, I discovered that several biological pathways, such as inflammatory response and
epigenetic pathway, are altered in mutant HSCs, which might contribute to the drug resistances seen in
leukemia cells with mutant p53. These finding are meaningful, as most leukemia patients are resistant
to the conventional chemotherapies overtime. I hope that my research in cancer biology labs will help
cancer patients and improve their quality of life in the near future. Though laborious, I have found independent research extremely rewarding. Not limited in mastering of
crucial techniques in biomedical imaging and cancer biology, I have also owned several peer-reviewed
publications. In addition to co-authoring two papers from Louie lab and another two from my summer
research labs, I recently submitted a manuscript for my previous fiber-coupled LEDs project, where I
am the first author. I also had another co-authored paper of leukemia and pre-leukemia HSCs from Liu
lab currently under revision. Besides, I have presented my research projects at several conferences.
When pursuing a Ph.D., I would like to get more rigorous training on innovative scientific thinking and
cutting-edge technologies. The Ph.D. program in Biomedical Engineering at Yale University is my
best choice, because Yale is a leader in the fields of nuclear medicine and magnetic resonance imaging.
For instance, the traditional data-driven gated reconstructions for correcting the effects of respiratory
motions during PET scans usually greatly reduce SNRs on the images. Meanwhile, to compensate this
issue, Ren et al. from the Yale PET Center have developed a novel event-by-event motion-correction
method, which incorporates information from the list-mode time-of-flight data through the centroid-ofdistribution
(COD) algorithm. This correction has successfully led to great reductions of noises and
blurs on PET images. In addition to the Yale PET Center, the Biomedical Engineering department also
has strong collaborations with the MRRC, IPAG, Y-TRIC, and the Bioimaging Science at Yale School
of Medicine. I can hence obtain valuable opportunities to learn skills from my peers and experts in the
interdisciplinary fields.
Earlier in this year, I have discussed the ongoing projects and potential rotation opportunities with two
professors in Yale University, including Dr. Richard Carson and Dr. James Duncan. Since I have
developed significant interest and useful skills for PET during my undergraduate studies, I am eager to
study the list-mode PET reconstructions or kinetic modelling of PET radiotracers at the Carson group.
Given that the outstanding imaging analysis and post-processing play important roles in the accurate
disease diagnosis and the advanced interventional surgeries, I am attracted by the Duncan group for the
algorithm designs in neuroimaging and cardiac functions analysis. The Biomedical Engineering Ph.D.
program at Yale University will prepare me well for a research career in biomedical imaging in the