4D DSA and 4D Fluoroscopy: Validation of Diagnostic and Therapeutic Capabilities

描述（由申请人提供）：1980年，当DSA被引入时，最初的热情是该技术将首次能够使用静脉注射造影剂在广泛的基础上进行血管造影术。不幸的是，这种热情很快就消失了，因为很明显，由于任何单个投影上的动脉和静脉重叠，需要多次采集才能进行充分的诊断评估（其中每一次都与非常显着的造影剂剂量以及额外的造影剂剂量相关）。X射线曝光）。很快，真实的时间数字成像能力的使用被调整为与动脉内造影剂注射一起使用。 常规DSA以可变帧速率（时间序列）提供2D图像。类似地，X射线荧光透视以高帧速率提供2D显示。在过去的30年里，DSA主要与动脉内注射结合用于诊断目的，而其他血管造影方式（如CTA和MRA）则与静脉注射结合使用。尽管当前的3D旋转DSA确实提供了3D重建，但是图像不包含时间信息，并且尽管通过使用旋转视图可以在一定程度上克服血管重叠，但是重建体积中动脉和静脉的组合通常使得难以实现最佳可视化。由于限制C形臂机架定位的几何约束，使用C形臂系统实现的荧光透视通常不能提供用于介入设备的递送和部署的最佳视图（工作视图）。这不仅损害了某些介入治疗的安全性，而且往往导致无法为患者提供血管内治疗，需要他们接受更具侵入性的传统外科手术。在过去的几年中，我们已经开发了MRA技术，包括次奈奎斯特采集和约束重建，允许加速因子高达1000。这些已经消除了空间和时间分辨率之间的传统折衷，并且已经提供了使用少至1cc的静脉内钆的对比度增强的MRA技术和相位对比技术，其已经促进了诸如血管压力梯度1-4的非侵入性测量的新应用。约束重建的原理也已经扩展到其他医学成像领域，其中已经报告了显著的剂量降低或SNR增加5-7。这些原理中的许多可以应用于X射线DSA，以大大提高可以获得3D时间分辨体积的速率。我们最近开发了一种基于C形臂的4D DSA方法，该方法以高达30/s的帧率提供一系列完全时间分辨的3D DSA体积（4D-DSA），具有比当前MRA和CTA技术更高的时间和空间分辨率。我们还开发了一种4D荧光透视方法，该方法允许以任何期望的角度对虚拟路线图进行荧光透视查看，而无需重新定位C形臂机架。拟议的研究的目的是验证这些技术，并使它们达到一个点，他们准备广泛传播和临床使用。

DESCRIPTION (provided by applicant): In 1980 when DSA was introduced there was initial enthusiasm that the technique would, for the first time, enable the ability to perform angiographic procedures, on a wide spread basis, using an intravenous injection of contrast medium. Unfortunately, this enthusiasm rather quickly dissipated as it became evident that because of the overlap of arteries and veins on any single projection, multiple acquisitions were required for adequate diagnostic evaluations (each of these was associated with a very significant contrast medium dose as well as additional x-ray exposure). Quickly, the use of the real time digital imaging capabilities was adapted for use with intra-arterial contrast injections. Conventional DSA provides 2D images at variable frame rates (a time series). Similarly, X-ray fluoroscopy offers a 2D display at high frame rates. Over the last 3 decades, DSA has been used primarily in conjunction with intra-arterial injections for diagnostic purposes while other angiographic modalities such as CTA and MRA have been used in connection with intravenous injections. Although current 3D rotational DSA does provide a 3D reconstruction, the images contain no temporal information, and although vessel overlap can be overcome to some extent through the use of rotational views, the combination of arteries and veins in the reconstructed volume often makes optimal visualization difficult. Because of the geometrical constraints that limit positioning of the C-arm gantries fluoroscopy implemented using C-arm systems often cannot provide optimal views for delivery and deployment (working views) of interventional devices. This not only impairs the safety of some interventions but also often results in an inability to offer patients endovascular treatment, requiring that they undergo more invasive traditional surgical interventions. During the past several years we have developed MRA techniques involving sub-Nyquist acquisition and constrained reconstruction that permit acceleration factors up to 1000. These have removed the traditional tradeoffs between spatial and temporal resolution and have provided contrast-enhanced MRA techniques using as little as 1 cc of intravenous gadolinium and phase contrast techniques that have facilitated new applications such as non-invasive measurement of vascular pressure gradients 1-4. The principles of constrained reconstruction have also been extended to other areas of medical imaging where significant dose reductions or SNR increases have been reported 5-7. Many of these principles can be applied to X-ray DSA to greatly increase the rate at which 3D time resolved volumes can be obtained. We have recently developed a C-arm based 4D DSA method that provides a series of fully time resolved 3D DSA volumes (4D-DSA) at frame rates of up to 30/s with higher temporal and spatial resolution than current MRA and CTA techniques. We also have developed a 4D Fluoroscopy method that permits fluoroscopic viewing of virtual roadmaps at any desired angle without a need to reposition the C-arm gantries. The purpose of the proposed research is to validate these techniques and to bring them to a point where they are ready for wide spread dissemination and clinical usage.