Photon-Counting Spectral CT to Reduce Dose and Detect Early Vascular Disease

描述（由申请人提供）：我们的长期目标是在出现症状性后果之前，在动脉粥样硬化的最早阶段进行无创检测，并优化光谱CT以供最终临床使用。该提案的目标是使用基于光子计数探测器的光谱CT，以比使用基于积分探测器的常规CT可能的辐射剂量低得多的辐射剂量提供所需的空间分辨率和材料辨别灵敏度。实现这一目标的重要性在于，在不可逆的后果如心肌梗死或中风之前，有效治疗影响血管壁的病理机制将在个人和社会层面上都更加有效，并且更便宜。此外，我们提出的研究将提供必要的知识，以减少常规CT成像所需的辐射剂量，并为其他应用程序的光谱CT，需要提高灵敏度的材料歧视。该项目的创新之处在于使用了基于光子计数探测器的 全身CT扫描仪开发和验证所需的采集、重建和处理技术。使用光谱CT的基本原理是，它提供了比其他非侵入性方法（如3D MRI和放射性核素成像）更高的时空分辨率，比传统CT受部分体积平均的影响更小，并且能够区分和量化所有相关斑块成分的浓度。此外，电子噪声对使用光子计数探测器的光谱CT的影响可以忽略不计。这是重要的，因为将X射线光谱分解成提高材料辨别灵敏度所需的小能量仓大大减少了每个仓的光子计数。此外，利用能量域相关性的降噪方法可用于增加对低浓度材料的灵敏度。因此，不需要增加辐射暴露。窄谱能量箱的使用还极大地降低了由于动脉壁钙化和/或管腔内对比度而引起的局部射束硬化效应。使我们能够实现目标的具体目标是：目标1 -采用光子计数探测器技术开发用于全身光谱CT的优化采集、重建和处理技术。我们将充分表征光谱CT系统;确定能量箱的最佳数量、宽度和位置;实施和评估降噪算法和算法，以区分和量化共定位斑块成分的浓度;确定系统精度并评估部分体积平均的影响。目的2 -确定全身光谱CT识别人尸体动脉粥样硬化斑块成分的灵敏度和特异性。目的3 -在麻醉猪中，使用碘基造影剂定量主要动脉壁的新生血管形成，作为动脉粥样硬化斑块形成的早期指标。

DESCRIPTION (provided by applicant): Our long-term objective is to non-invasively detect atherosclerosis in its earliest stages, before symptomatic consequences occur, as well as to optimize spectral CT for ultimate clinical use. The goal of this proposal is to use photon-counting-detector-based spectral CT to provide the required spatial resolution and material discrimination sensitivity at much lower radiation doses than would be possible using integrating-detector- based conventional CT. The significance of achieving this goal is that effective treatment of the pathological mechanism(s) affecting the vascular wall, prior to irreversible consequences such as myocardial infarction or stroke, would be considerably more effective, and less expensive, at both the individual and societal levels. Further, our proposed studies will provide knowledge essential for reducing the radiation doses required in routine CT imaging and for other applications of spectral CT that require increased sensitivity for material discrimination . The innovation of this project lies in the use of a photon-counting-detector-based whole-body CT scanner to develop and validate the needed acquisition, reconstruction, and processing techniques. The rationale for using spectral CT is that it offers improved spatio-temporal resolution over other non-invasive methods, such as 3D MRI and radionuclide imaging, is less affected by partial volume averaging than conventional CT, and is capable of discriminating and quantifying the concentration of all relevant plaque components. Also, the effects of electronic noise on spectral CT using photon-counting detectors are negligible. This is important because breaking the x-ray spectrum into the small energy bins needed for improved material discrimination sensitivity drastically reduces the photon counts per bin. Further, noise reduction methods that exploit energy domain correlations can be used to increase the sensitivity to low concentrations of materials. Thus, increased radiation exposures will not be required. Use of narrow spectral energy bins also greatly reduces the local beam hardening effects due to arterial wall calcification and/or intraluminal contrast. The specific aims that wil enable us to achieve our goal are: AIM 1 - Develop optimized acquisition, reconstruction and processing techniques for whole-body spectral CT with photon-counting detector technology. We will fully characterize the spectral CT system; determine the optimal number, width and location of energy bins; implement and evaluate noise reduction algorithms and algorithms to discriminate and quantify the concentration of co-localized plaque components; and determine system accuracy and evaluate the impact of partial volume averaging. AIM 2 - Determine the sensitivity and specificity of whole-body spectral CT for the identification of atherosclerotic plaque components in human cadavers. AIM 3 - In anesthetized pigs, quantify neovascularization in major arterial walls, as an early indicator of atherosclerotic plaque formation, using iodine-based contrast agents.