Development of SPECT for in vivo 3D cell tracking

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Medical imaging is undergoing a revolution fueled by both advances in imaging technology and advances in imaging probes. New probes, arising from discoveries in molecular biology, allow imaging of very specific molecular events - provided that imaging technology can be adapted to their detection. Central to realizing the potential of the medical imaging revolution are three challenges: (1) Imaging molecular pathways: Imaging of multiple probes simultaneously to follow related molecular processes; (2) Providing context: Combining the imaging of probes with the imaging of anatomy to localize the molecular events relative to underlying anatomical structure; and (3) Ensuring accessibility: Making the imaging technology cost-effective and widely deployable. An imaging technology with the potential to meet these challenges is Single Photon Emission Computed Tomography (SPECT). SPECT is inherently multi-spectral, allowing for the simultaneous imaging of multiple radioactively labeled probes. The rich functional information provided by SPECT can be placed into the context of underlying anatomy through hybrid SPECT/CT, which is readily available and increasingly popular. Finally, SPECT is already deployed widely throughout Canada. The inevitable evolution of SPECT to solid-state detector technology promises to multiply its multi-spectral capabilities. Our development of reconstruction algorithms designed for imaging large objects with smaller cost-effective detectors will help make this evolution more economically feasible. We propose to optimize SPECT for in vivo cell tracking - an emerging niche with applications in cardiac, neural, and pancreatic regenerative therapy; oncology; and developmental biology. Our theoretical work includes state-of-the-art computer simulations and reconstruction techniques; while our experimental efforts focus on phantoms and large animals (canines). The focus of our application is monitoring myocardial stem cell therapy in a canine model of heart disease because of availability in our research institute, and because it represents the majority of challenges to be solved in molecular imaging and cell tracking.