Flow 3D+T Image Reconstruction Algorithms for Enhanced Cerebral Angiography

描述（由申请人提供）：这项R21研究旨在促进增强的时空图像重建和分析，以实现更安全的神经血管手术。目前的术中脑血管造影图像是二维投影，需要操作者实时解读。在时间敏感的环境中，操作者必须在2D x射线血管造影投影延时图像和复杂的3D脑血管结构之间进行心理映射，以便检测和定位干预期间可能出现的近端和远端血栓栓塞事件。在介入治疗（如颈动脉支架置入或动脉瘤盘绕）过程中，如果不能检测到部分或完全阻塞的血栓，可能会导致下游脑组织的血流中断，从而导致缺血性中风。目前可用的术内三维断层血管图不包含局部血流信息。目前还无法获得所需的动态3D （3D+T）图像，因为：1)对于现有的基于x射线的断层扫描设备来说，血管中的血流太快了；2)如果这种技术可用，将使患者接受相当多的额外辐射暴露和注射造影剂。检测术中血栓栓塞事件将使他们的治疗避免中风。成功检测的可能性反过来将显著受益于以下能力：1)重建3D+T图像，从多个角度实时估计和监测血流；2)获得节段性血流和区域灌注的定量信息；3)检测和定位手术引起的时空变化和血流异常（例如形成或栓塞的血栓或斑块碎片、内膜剥离或医源性血管痉挛）。只要这种能力及时发生，而不需要额外的分散注意力的人为干预或对患者的辐射暴露。为了解决这些问题，我们开发了（目标1）用于同时平滑和分割的变分能量公式，该公式以统一的方式融合了先验信息和测量数据。这种方法同时演变了整个脉管系统的流动，并避免了下游错误的传播和积累。接下来，将开发分析方法，从血流模式中提取信息，以便检测和定位位于未直接成像区域的异常。重建、异常检测和定位算法都将使用虚拟数据进行测试，以证明处理模糊的能力，然后是来自流模型的台式数据，其中包含模拟的动态分支闭塞。算法还将通过回顾性分析从先前已知不良事件（如血栓栓塞）的手术中收集的3D和动态2D （2D+T）图像来验证。该结果将为该方法在算法优化和前瞻性临床评价方面的扩展奠定基础。

DESCRIPTION (provided by applicant): This R21 research aims to contribute to enhanced spatiotemporal image reconstruction and analysis to achieve safer neurovascular procedures. Current intra-procedural cerebral angiographic images are two-dimensional projections, which require demanding real-time interpretation by the operator. In a time-sensitive environment, the operator must perform the mental mapping between 2D X-Ray angiographic projection time lapse images and the complex 3D structure of the cerebrovasculature in order, among other, to detect and locate proximal and distal thromboembolic events that may have arisen during an intervention. Failure to detect partially or completely obstructive clots during an intervention such as carotid stenting or aneurysm coiling, could result in blood flow interruption to downstream brain tissue leading to ischemic stroke. Currently available intra-procedural tomographic 3D vascular maps do not contain local blood flow information. Desired dynamic 3D (3D+T) images are currently unavailable because: 1) blood flow across the vasculature is too rapid for available X-ray based tomography units, and 2) such technology, were it available, would subject the patient to considerable additional radiation exposure and contrast agent injection. Detecting intra-procedural thromboembolic events would enable their treatment to avoid a stroke. The likelihood of successful detection in turn would significantly benefit from the ability to 1) reconstruct 3D+T images to estimate and monitor blood flow in real time from multiple perspectives, 2) obtain quantitative information of segmental blood flow and regional perfusion, and 3) detect and locate procedure-induced spatio-temporal changes and blood flow anomalies (e.g. formed or embolized thrombus or plaque fragment, intimal dissection, or iatrogenic vasospasm), provided that this capability occurs in a timely fashion without additional distracting human intervention or radiation exposure to the patient. To address these issues, we developed (Aim 1) a variational energy formulation for simultaneous smoothing and segmentation that fuses in a unified fashion prior information and measurement data. This approach simultaneously evolves flow over the entire vasculature and avoids propagation and accumulation of errors downstream. Next, analytical methods will be developed for extracting information from blood flow patterns to enable the detection and localization of abnormalities situated in areas not directly imaged. Both the reconstruction and anomaly detection and localization algorithms will be tested using phantom data to demonstrate the ability to deal with ambiguity, followed by benchtop data from the flow model incorporating simulated dynamic branch occlusions. The algorithms will also be validated by retrospective analysis of 3D and dynamic 2D (2D+T) images collected from previous procedures with known adverse events such as thromboembolism. The results will form the basis for expansion of this approach to algorithm optimization and prospective clinical evaluation. PUBLIC HEALTH RELEVANCE: It is difficult to interpret from two-dimensional X-ray images what is inside our body. They do not reveal always so well the nature of the blood flow inside the body, nor the possible occurrence of blood clots. This research overcomes this limitation by providing radiologists and surgeons with three-dimensional images of blood flow in vessels. These images are easier to interpret, more revealing and will make it possible for doctors to detect, locate and take actions to correct abnormalities such as clots, as well as perform a safer and faster surgery thus saving lives and money.