Biomedical Engineering Associate Project Scientist Junwei Du Receives Two NIH R01 Grants for Developing High-Performance Small-Animal PET Scanners

Junwei Du received his second NIH R01 grant for $2.3 million to develop a high-resolution total-body small animal PET scanner (H2RS PET) for preclinical studies using mouse models. Du is an associate project scientist in professor Simon Cherry's biomedical engineering (BME) lab.  

“This device is 17 cm long, covering the entire body of a mouse," said Du. "It has a 0.5 mm spatial resolution and over 20% sensitivity. It enables us to detect pathologies such as cancer earlier and more easily, using a lower radiation dose.” 

Long History of Imaging Research

Du was previously granted $2.4 million from the NIH in 2020 to develop a high-sensitivity total-body small animal PET scanner. This scanner will be helpful for ultra-low-dose preclinical imaging studies, including imaging low levels of receptor binding and transgene expression and observing therapeutic cell circulation in mouse and rat models. In two years, the Cherry lab intends to begin using this and the newest scanner with small animals. 

"Members of the Cherry Lab have worked for years to develop the basic detector elements and readout electronics for these two scanners. We are fortunate now to have both these major projects funded. With these two scanners, our department continues its long history of developing innovative small-animal PET scanners," Du said. "We hope that these two scanners will become useful preclinical tools for researchers within and beyond our department." 

Cherry commented, “These awards build on years of detailed and cutting-edge technology development work by Dr. Du, and it is exciting to now have the necessary funding to develop entire prototype imaging systems to realize the potential of the technology for improving preclinical imaging."

Technical Challenges, Possibilities, and Next Steps

The second scanner, the H2RS PET device, approaches the theoretically achievable spatial resolution limit of PET imaging. It improves the spatial resolution by more than twofold with a comparable sensitivity or enhances the detection sensitivity by 20 times for a similar spatial resolution. The improvement could enable applications including high-resolution brain studies and fast total-body dynamic imaging studies in mouse models. The new scanner will develop and inform the paradigms and protocols that feed into human total-body PET studies and brain studies. 

"It can be a challenge to shrink a scanner down," explains Du. "Even though it involves less material, it's physically harder to build something where the crystals inside are smaller, and there's less room for error. The hardware presents even more difficulties than the software." Du says it is challenging to improve resolution further without sacrificing other performance needs, such as sensitivity. The next steps are enhancing timing resolution and speeding up the process of mathematically analyzing the results.

The Cherry Lab, in collaboration with Ramsey Badawi in radiology, has developed a series of PET scanners in recent years, including the EXPLORER total-body human PET/CT scanner and the miniEXPLORER I and II PET scanners for large-animal studies, and is currently a partner in the development of the NeuroeXplorer, a next-generation human brain PET scanner. 

There are two students currently in the Cherry lab and they hope to bring more aboard in the future. "People here have worked on advancing imaging technology for 20 to 30 years," says Du. "UC Davis is a great place for this research."