Hybrid Imaging and the Relationship Between Physics and PET/MRI

Hybrid imaging is the fusion of two or more imaging modalities to form a new technique, leading to a new or more powerful modality. For Dr. Youngho Seo, PhD, Associate Professor in Residence and Director of Nuclear Imaging Physics at the UCSF Department of Radiology, working with hybrid imaging resulted in new opportunities.  “My work on hybrid imaging led me to work on PET/MRI,” explained Dr. Seo.

“There are many traditional physicists like me who came into the imaging field because of the similarities in technical development, especially PET scans.” His work impacts patient safety and treatment outcomes.

Physics plays a central role in radiological imaging. According to Dr. Seo, imaging is purely experimental particle physics because, “we detect particles in PET technology, thus detect radiation.”

Dr. Seo’s background makes him an expert on radiation dose. “Radiation reduction is not necessarily a matter of PET/CT versus PET/MRI, but the quality of technology we have for the PET portion,” he said. “UCSF’s PET scanner portion of our PET/MRI machine is state-of-the-art. Because we use high quality technology, we can reduce radiation from the PET portion of the scanner.”

Reducing radiation is important, but it’s not the only benefit patients get from hybrid approaches.

“There is a synergy when you deploy the simultaneous technologies. For example, with PET and CT, CT provides additional information for PET, and PET, enabled by CT, provides even more information than it would alone. It’s not really one plus one is two, because the end result is bigger than two.”

He explains further, that on a practical level, “it is better logistically for the patient because they get two scans in one appointment. We can also use the PET screening to learn more about the patient’s condition and get new health information for them. And because the technologies image better together, we can use less radiation.”

Dr. Seo also develops software to perform functions like image processing and the measurement of imaging data. “My primary focus is how calculating data affects treatment outcomes. When a patient has cancer, for example, or cardiovascular therapy, or a pacemaker, we look at the data to learn more about how imaging can benefit them,” he explains. “Instead of just finding an area that’s abnormal, it’s ideal to have some quantitative index of it, like a number. This measurable index can be used to guide treatment response, planning, drug trials and more.”

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Youngho Seo, PhD, is an associate professor in residence and director of Nuclear Imaging Physics in the Department of Radiology and Biomedical Imaging, associate professor in residence in the Department of Radiation Oncology at the University of California, San Francisco, and physicist faculty scientist at Lawrence Berkeley National Laboratory. He received his bachelor's degree in Physics from Korea Advanced Institute of Science and Technology (KAIST). He completed two master's degrees in Physics at the University of Alabama in Huntsville, and at the University of California, Los Angeles (UCLA). Dr. Seo completed his PhD in Physics from UCLA under the supervision of Professor David Cline, followed by postdoctoral training at the same institution. He joined the UCSF Physics Research Laboratory in 2003, and was trained under the supervision of Professor Bruce Hasegawa before joining the faculty in 2006.

Dr. Seo leads a group of physicists and engineers working in the field of radionuclide and X-ray imaging instrumentation and physics, and directs the UCSF Physics Research Laboratory (PRL). His primary research focus is to use quantitative SPECT/CT, PET/CT, and PET/MR molecular imaging for a broad range of research areas from small animal imaging using dedicated animal imaging systems and basic instrumentation development to physics analysis of clinical research data. Dr. Seo also directs the preclinical PET/SPECT/CT/Optical imaging core facility at the UCSF Center for Molecular and Functional Imaging at China Basin.

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