Dynamic Cardiac SPECT Imaging

描述（由申请人提供）：心脏病是当今美国死亡和残疾的主要原因。单光子发射计算机断层扫描 (SPECT) 心肌灌注成像 (MPI) 目前是冠状动脉疾病 (CAD) 检测和风险分层中应用最广泛的无创方法。假设：与传统 MPI SPECT 静态图像的视觉解释相比，动态心脏 SPECT 的冠状动脉血流储备 (CFR) 参数图像将提供更灵敏的梗死、缺血和血流动力学意义边缘病变的测量。该应用恰逢最近推出的新型心脏应激剂（可加快冠状动脉充血反应）和新型专用心脏 SPECT 系统（可快速采集动态数据）。然而，还没有相应的算法开发将动态采集的数据简化为诊断临床参数。该提案将通过应用算法处理使用现有 SPECT 系统和新的专用心脏 SPECT 系统在临床研究中获取的动态数据，来研究动态 SPECT 的临床作用。开发的协议和算法可以在诊所实施，无需额外费用。在医疗费用高昂且不断上涨的时期，这是该方法的另一个优势。拟议的工作应用数学工具来准确、精确地量化动力学参数；使用计算机模拟、模型实验和临床研究验证这些方法；并将完善动态心脏 SPECT 的临床作用。提出的创新方法包括：使用跳动心脏的多分辨率时空力学模型来估计描述示踪剂浓度和心脏变形随时间变化的模型参数（5D动态建模）；开发可变形模型，以生成更真实的心脏、肺和专利运动数据，以验证运动校正算法。一个独特的方面是我们能够直接从使用慢速相机旋转速度的投影来估计动力学模型参数，包括血液输入函数，而无需动脉血采样。 SPECT 和 CT 之间的错位将得到纠正。动力学信息将用于根据器官中示踪剂的动力学来估计来自不同器官的散射成分。这些新算法与新型快速专用心脏 SPECT 相机的结合将能够在与目前定量 PET 相同的时间内定量 CFR。此外，我们的方法将使动态 SPECT 在成像诊所中使用无法执行快速采集的现有扫描仪变得有用。开发的方法不仅适用于使用各种灌注和代谢剂对心肌进行成像，这可能会影响我们对各种心血管适应症的病理生理学的理解，而且还适用于对肿瘤和其他器官系统（例如肾脏和大脑）进行成像。

DESCRIPTION (provided by applicant): Heart disease is the leading cause of death and disability in the United States today. Single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) is now the most widely applied noninvasive method for the detection and risk stratification of coronary artery disease (CAD). Hypothesis: Parametric images of coronary flow reserve (CFR) from dynamic cardiac SPECT will provide more sensitive measures of infarct, ischemia, and lesions on the margin of hemodynamic significance than visual interpretations of static images of conventional MPI SPECT. This application is well timed with the recent introduction of new cardiac stressing agents that allow faster hyperemic response of coronary arteries, and new dedicated cardiac SPECT systems enabling rapid acquisition of dynamic data. However, there has not been accompanying development of algorithms that reduce dynamically acquired data to diagnostic clinical parameters. This proposal will investigate clinical roles of dynamic SPECT by applying algorithms for processing dynamic data acquired in clinical studies using existing SPECT systems as well as a new dedicated cardiac SPECT systems. The developed protocols and algorithms can be implemented in the clinic without additional costs. This is a further advantage of the method in this time of high and rising healthcare costs. The proposed work applies mathematical tools to accurately and precisely quantify kinetic parameters; validates these methods using computer simulations, phantom experiments, and clinical studies; and will perfect clinical roles for dynamic cardiac SPECT. Innovative methods proposed include: use of multi-resolution spatiotemporal mechanical models of the beating heart to estimate model parameters that delineate changes in tracer concentration and cardiac deformation as a function of time (5D dynamic modeling); and development of a deformable phantom to generate more realistic data of cardiac, lung, and patent motion for validation of motion correction algorithms. An unique aspect is our ability to estimate kinetic model parameters, including the blood input function, directly from projections using slow camera rotation speeds without the need for arterial blood sampling. Misalignment between SPECT and CT will be corrected. Kinetic information will be used to estimate scatter components from different organs based on the kinetics of the tracer in the organ. The incorporation of these new algorithms with the new fast dedicated cardiac SPECT cameras will enable quantitation of CFR in a time equal to that of present quantitative PET. Furthermore, our methods will make dynamic SPECT useful in imaging clinics with existing scanners that cannot perform rapid acquisitions. The methods developed will not only be applicable for imaging the myocardium with a variety of perfusion and metabolic agents, which could impact our understanding of the pathophysiology of a variety of cardiovascular indications, but will also have application for imaging tumors and other organ systems such as the kidney and brain.