Real-time cardiovascular MRI and co-registration technical development

在过去的一年中，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射线共同配准的MRI，以及独立的实时MRI。 来自MRI数据集的静态3D路线图用于增强X射线心血管介入手术的图像引导，实际上已在本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表示心脏和呼吸运动期间的心血管解剖结构。 我们已经开发了一个系统来测量呼吸和心脏运动的实时MRI扫描，并推导出一组仿射模型，可用于跳动和呼吸的3D路线图覆盖在现场X射线。 我们还开发了强大的全自动数学技术来配准成像模式之间的基准标记。 我们与行业合作者合作，将我们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。 我们将继续加强在介入性MRI实验期间以及在X射线和MRI之间转移期间安全患者血流动力学监测和记录的系统。 我们开发了一种能够自适应噪声消除的系统，以滤除RF和磁梯度干扰。 我们继续致力于无线生理遥测系统。 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.汉森已经使用由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。 我们已经成功地集成了非笛卡尔并行成像的交互式采集和重建设置，并证明了实时重建和可视化是可能的相对复杂的重建算法。 这已经与扫描仪软件集成，以允许与其他序列组件无缝组合。 这已经作为一个开源图像流框架传播，该框架在生物医学成像中的广泛应用中变得非常流行。 我们已经开发了一个系统，为操作员提供多个同时表示的实时MRI数据平衡的时间和空间分辨率交互。 操作员选择所需的表示。 我们已经实现了黄金角实时MRI的时间分辨率的交互式选择。 我们正在将非常成功的本地实时MRI软件环境迁移到商业平台上，以促进NIH以外的翻译，并加强行业和大学的合作。这需要大量的开发来更新主力实时MRI脉冲序列，以促进快速多作者或多机构原型设计。 这一发展允许在技术专家而不是物理学家的工作人员支持下进行研究性人体MRI导管插入术，反映了一个完善的临床相关系统。我们还将继续增强实时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临床导管插入期间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合作者合作，探索表面线圈射频激励策略，以减少传导导管器械上的能量沉积。 我们已经能够减少大约一半的能量沉积，而不会显着降低图像质量，但寻求进一步减少发热。 我们已经开始研究减少能量沉积的实时MR成像脉冲序列，以提高使用导电导管器械进行介入性MRI的安全性，避免发热。 这在植入起搏器和除颤器等器械的患者的安全MRI中具有额外的实用性。 我们还将继续开发新的实时MRI方法，或设计实时MRI的本地非商业实施方案，以满足正在开发的程序的需求。

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.