Imaging Multiple Contrast Mechanisms in Deep-Tissue using Diffuse Optical Tomography

Diffuse optical tomography is a unique imaging tool that can noninvasively probe biological events in deep-tissue. Its application is currently being extended from basic research into preclinical and clinical arena. From the image formation point of view, diffuse optical tomography is based on solving the inverse problem of photon transport in optically diffusive tissue. While enabling deep-tissue probing, diffusive photons lead to relatively low structural resolution. As a result, multi-model imaging with MRI and CT is a natural solution to enhance tomographic image reconstruction and to facilitate registration of functional and structural data. From the point of view of imaging contrast, diffuse optical tomography is able to probe hemoglobin oxygenation, concentration of fluorescently labeled markers, and biological events associated with fluorescence lifetime and spectra such as Forster resonance energy transfer and synchronous fluorescence. A latest addition to the contrast mechanisms is the optical photons induced by high-energy radiation photons/electrons used in radiation therapy, which opens a door to cancer treatment and research. I will discuss the principles of diffuse optical tomography, followed by our work in imaging tissue oxygenation, fluorescence, time-resolved spectral signals, and potential clinical uses in radiation oncology.

Dr. Xiaofeng (Steve) Zhang obtained his PhD degree in Electrical Engineering from the University of Illinois at Urbana-Champaign in 2005. He was one of the earliest researchers working on multimodal imaging of human brain using diffuse optical tomography and MRI. He later moved onto his post-doctoral work on multimodal small animal imaging at the Pennsylvania State University for two years, before joining the Duke University Medical Center in 2007. Here at Duke, he continued his work in multimodal small animal imaging and, recently, expended his research into new areas of time-/spectral-resolved imaging and Cerenkov emission tomography. Lately, Dr. Zhang was appointed Assistant Professor of Radiology and is currently a faculty member of the Fitzpatrick Institute for Photonics.