Real-time cardiovascular MRI and co-registration technical development

在过去的一年里，我们继续增强成像平台，以指导基于心血管导管的治疗。其中包括与传统X射线联合注册的MRI，以及独立的实时MRI。 从MRI数据集获得的静态3D路线图被用于增强X射线心血管介入手术的图像指导，并确实已在该实验室用于开发新的治疗方法，如二尖瓣环扎成形术。静态路线图不能准确反映心脏和呼吸运动期间的心血管解剖结构。我们已经开发了一种系统，可以从实时MRI扫描中测量呼吸和心脏运动，并推导出一套仿射模型，可以用来敲击和呼吸覆盖在实时X光上的3D路线图。我们还开发了健壮的全自动数学技术来配准成像模式之间的基准标记。我们与一家行业合作伙伴合作，将我们在当地开发的环境转化为临床工业原型，用于成人和儿童的测试。 在介入性MRI实验期间以及在X射线和MRI之间的传输期间，我们继续加强安全的患者血流动力学监测和记录系统。我们开发了一种能够自适应噪声抵消的系统，以滤除射频和磁梯度干扰。我们继续致力于研制无线生理遥测系统。我们将开始与SBIR承包商合作，将这项工作转化为临床工业原型，用于成人和儿童的测试。 我们的合作者Michael S.Hansen使用面向游戏的图形处理单元提供的廉价并行计算资源来加速计算密集型MRI数据的重建。我们已经成功地将非笛卡尔并行成像集成到交互式采集和重建设置中，并证明了对于相对复杂的重建算法，实时重建和可视化是可能的。这已经与扫描仪软件集成在一起，以允许与其他序列组件无缝结合。这是一个开源的图像流传输框架，在生物医学成像中得到了广泛的应用。 我们开发了一个系统，为操作员提供实时MRI数据的多种同时表示，以交互方式平衡时间和空间分辨率。操作员选择所需的表示。我们实现了时间分辨率交互式选择的黄金角度实时磁共振成像。 我们正在将我们非常成功的本地实时磁共振软件环境迁移到一个商业平台上，以促进NIH以外的翻译，并加强产业界和大学的合作。这需要相当大的发展来更新主要的实时MRI脉冲序列，以促进快速的多作者或多机构原型制作。这一发展使得研究性的人类MRI插管可以在技术专家而不是物理学家的工作人员支持下进行，反映了一个精致的和临床相关的系统。我们还继续增强实时MRI成像主机和图像重建环境，例如，以交互方式平衡时间和空间分辨率，并在实时MRI临床插管过程中增强操作员工作流程。我们继续与行业合作伙伴合作，将我们在当地开发的能力转化为临床工业原型，用于成人和儿童的测试。 我们与NHLBI的合作者合作，探索表面线圈射频激励策略，以减少导电导管设备上的能量沉积。我们已经能够在不显著降低图像质量的情况下将能量沉积减少大约一半，但寻求进一步减少加热。 我们已经开始研究减少能量沉积的实时磁共振成像脉冲序列，以提高使用导电导管设备的介入性磁共振成像的安全性，以避免发热。这在植入起搏器和除颤器等植入设备的患者的安全MRI中具有额外的实用价值。 我们还继续开发实时磁共振成像的新方法，或设计实时磁共振成像的本地非商业性实施例，以适应正在开发的程序的需要。

During the past year we have continued enhancement of imaging platforms to guide cardiovascular catheter based treatments. These have included co-registered MRI with conventional X-ray, as well as standalone real-time MRI. Static 3D roadmaps derived from MRI datasets are used to enhance image guidance for X-ray cardiovascular interventional procedures, and indeed have been used in this lab to develop novel treatments such as mitral cerclage annuloplasty. Static roadmaps do not accurately represent cardiovascular anatomy during cardiac and respiratory motion. We have developed a system to measure respiratory and cardiac motion from real-time MRI scans and to derive a set of affine models which can be used to beat and breath the 3D roadmaps overlaid on live X-ray. We also have developed robust fully automatic mathematical techniques to register fiducial markers between imaging modalities. We have worked with an industry collaborator to translate our locally developed environment into a clinical industrial prototype for testing in adults and children. We continue to enhance a system for safe patient hemodynamic monitoring and recording during interventional MRI experiments and during transfer between X-ray and MRI. We have developed a system capable of adaptive noise cancellation to filter out RF and magnetic gradient interference. We continue work towards a wireless physiological telemetry system. We will begin work with an SBIR contractor collaborator to translate this work into a clinical industrial prototype for testing in adults and children. Our collaborator Michael S. Hansen has used inexpensive parallel computing resources afforded by game-oriented graphics processing units to accelerate reconstruction of computationally-intensive MRI data. We have successfully integrated non-Cartesian parallel imaging in an interactive acquisition and reconstruction setup and demonstrated that real-time reconstruction and visualization is possible for relatively complicated reconstruction algorithms. This has been integrated with the scanner software to allow seamless combination with other sequence components. This has been disseminated as an open-source image-streaming framework that has become very popular with extensive applications in biomedical imaging. We have developed a system to provide the operator multiple simultaneous representations of real-time MRI data balancing temporal and spatial resolution interactively. The operator chooses the desired representation. We have implemented golden-angle real-time MRI with interactive selection of the temporal resolution. We are migrating our highly successful local real-time MRI software environment onto a commercial platform to facilitate translation outside of NIH, and to enhance industry and university collaboration. This has required considerable development to update workhorse real-time MRI pulse sequences to facilitate rapid multi-author or multi-institution prototyping. This development has allowed investigational human MRI catheterization to be performed with the staff support of a technologist rather than a physicist, reflecting a polished and clinically-relevant system. We also continue to enhance the real-time MRI imaging host and image reconstruction environment, for example to balance temporal and spatial resolution interactively, and to enhance operator workflow during real-time MRI clinical catheterization. We continue work with an industry collaborator to translate our locally developed capabilities into a clinical industrial prototype for testing in adults and children. We have worked with NHLBI collaborators to explore surface coil RF excitation strategies to reduce energy deposition on conductive catheter devices. We have been able to reduce energy deposition by approximately half without significant degradation in image quality, but seek further reduction in heating. We have begun work on real-time MR imaging pulse sequences with reduced energy deposition to enhance the safety of interventional MRI using conductive catheter devices, to avoid heating. This has additional utility in safe MRI in patients with implanted devices such as pacemakers and defibrillators. We also continue to develop new approaches to real-time MRI, or to engineer local noncommercial embodiments of real-time MRI to suit the needs of procedures being developed.