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

描述(申请人提供)：1980年，当DSA被引入时，人们最初的热情是该技术将第一次能够在广泛的基础上使用静脉注射造影剂进行血管造影术。不幸的是，这种热情很快就消散了，因为很明显，由于任何单一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(每一次都与非常显著的造影剂剂量以及额外的X射线曝光有关)。很快，实时数字成像功能的使用被调整为用于动脉内造影剂注射。 传统的DSA以可变的帧速率(时间序列)提供2D图像。同样，X射线透视提供了高帧速率的2D显示。在过去的30年里，DSA主要用于动脉内注射用于诊断目的，而其他血管造影术如CTA和MRA也用于静脉注射。虽然目前的3D旋转DSA确实提供了3D重建，但图像不包含时间信息，尽管使用旋转切面可以在一定程度上克服血管重叠，但重建体积中的动脉和静脉的组合往往使最佳可视化变得困难。由于限制C形臂门架定位的几何约束，使用C形臂系统实施的透视通常不能为介入性设备的输送和部署(工作视图)提供最佳视角。这不仅损害了一些干预措施的安全性，而且往往导致无法为患者提供血管内治疗，要求他们接受更具侵入性的传统外科干预。在过去的几年里，我们开发了包括亚奈奎斯特采集和约束重建的MRA技术，允许加速系数高达1000。这些技术消除了空间和时间分辨率之间的传统折衷，并提供了仅使用1cc静脉注射Gd的对比度增强MRA技术和促进了新应用的相位对比技术，例如血管压力梯度1-4的非侵入性测量。限制性重建的原则也被扩展到医学成像的其他领域，据报道，这些领域的剂量显著减少或信噪比增加了5-7。这些原理中的许多可以应用于X射线DSA，以极大地提高获得3D时间分辨率体积的速度。我们最近开发了一种基于C-ARM的4DDSA方法，它以高达30/S的帧速率提供一系列完全时间分辨率的3D DSA体积(4D-DSA)，比目前的MRA和CTA技术具有更高的时间和空间分辨率。我们还开发了一种4D透视方法，允许以任何所需的角度透视查看虚拟路线图，而不需要重新定位C形臂门架。拟议研究的目的是验证这些技术，并使它们准备好广泛传播和临床应用。

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.