Development of SPECT for in vivo 3D cell tracking

医学成像正在经历一场由成像技术和成像探头的进步推动的革命。新的探针，从分子生物学的发现中产生，允许成像非常具体的分子事件-只要成像技术可以适用于它们的检测。实现医学成像革命潜力的核心是三个挑战：（1）成像分子通路：同时成像多个探针以跟踪相关的分子过程;（2）提供背景：将探针成像与解剖成像相结合，以定位相对于底层解剖结构的分子事件;以及（3）确保可访问性：使成像技术具有成本效益并可广泛部署。具有满足这些挑战的潜力的成像技术是单光子发射计算机断层扫描（SPECT）。SPECT固有地是多光谱的，允许多个放射性标记的探针的同时成像。SPECT提供的丰富的功能信息可以通过混合SPECT/CT置于基础解剖学的背景下，这是容易获得的，并且越来越受欢迎。最后，SPECT已经在加拿大各地广泛部署。SPECT向固态探测器技术的不可避免的演变有望使其多光谱能力倍增。我们开发的重建算法设计用于成像大型物体与较小的成本效益的探测器将有助于使这种演变更经济可行。我们建议优化SPECT在体内细胞跟踪-一个新兴的利基与心脏，神经和胰腺再生治疗的应用，肿瘤学和发育生物学。我们的理论工作包括最先进的计算机模拟和重建技术;而我们的实验工作集中在幻影和大型动物（犬类）。我们应用的重点是监测心脏病犬模型中的心肌干细胞治疗，因为我们研究所的可用性，并且因为它代表了分子成像和细胞跟踪中待解决的大多数挑战。

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.