FAST DYNAMIC 3D MRI USING ADAPTIVE SPATIAL ENCODING

描述(改编自申请者摘要)：本报告的主要目标 项目是开发一种快速动态3D MRI方法，该方法使用自适应 空间编码，可获得高分辨率的MRI数据(256x256x256) 尽可能接近实时运行(每1-2秒1个数据集) 对标准核磁共振扫描仪进行最小的硬件修改。这个目标就是 完全超出了像回声平面这样的现有磁共振成像方法的可能性 采用傅立叶编码和专门的渐变硬件的技术。 介入核磁共振的一些应用，这是我们医院的一个重点， 对动态3D MRI有特定要求，可以在 “开放式”磁共振扫描仪，没有专门的渐变线圈。其中最重要的 这些应用是MRI对热疗时间过程的监测 由于组织原因导致组织加热不均匀的疗法 异质性和邻近血管。另一个重要的应用是NEAR 用于微创的探头和导管的实时3D跟踪 治疗。具体地说，我们建议开发、实施、测试和 优化一种双向自适应编码的动态3D MRI方法 使用高翻转角2D空间选择性射频激励实现 从多维计算得到的近似最优编码的最小集合 3D图像估计的奇异值分解(MSVD) 最近采集的数据)与频率相结合，每次采集计算 在第三个方向上编码。主要目标的实现 这个项目的可能性只有三个重要的技术 预付款。首先，也是最重要的关于空间编码， 申请者最近报告说已经开发出了MSVD，一种强大的数字 可以确定近乎最佳的3D空间编码的数学工具。 其次，发展了一种简单、快速的数值计算方法。 实现射频脉冲波形计算的实验室 使用高翻转角度(90=A1)的非傅立叶编码，用于高信噪比扫描。 第三，在他们的设施中，他们有运营NEAR的能力 使用商业磁共振系统的实时自适应2D磁共振成像 修改附加的附加工作站。

DESCRIPTION (Adapted from Applicant's Abstract): The main goal of this project is the development of a fast dynamic 3D MRI method using adaptive spatial encoding that can acquire a high resolution MRI dates (256x256x256) operating in near real-time as possible (1 dataset per 1-2 seconds) with minimal hardware modifications to a standard MRI scanner. This goal lies well outside the possibilities of current MRI methods like echo planar techniques that employ Fourier encoding and specialized gradient hardware. A number of applications of interventional MRI, a focus in our hospital, have the specific requirement for dynamic 3D MRI that can operate on an "open" MR scanner with no specialized gradient coils. The most important of these applications is the MRI monitoring of the timecourse of thermal therapies during which non-uniform heating of tissue occurs due to tissue heterogeneity and nearby vessels. Another important application is the near real-time 3D tracking of probes and catheters used for minimally invasive therapies. Specifically, we propose to develop, implement, test and optimize a dynamic 3D MRI method that encodes adaptively in two directions using high flip angle 2D spatially selective RF excitations to implement a minimal set of near-optimal encodes computed from the multidimensional Singular Value Decomposition (MSVD) of a 3D image estimate (formed from recently acquired data) computed per acquisition, combined with frequency encoding in the third direction. The accomplishment of the main objective of this project is only possible due to three significant technological advances. First, and most important regarding spatial encoding, the applicants reported recently having developed the MSVD, a powerful numerical mathematical tool that can determine near-optimal 3D spatial encoding. Second, a simple fast numerical procedure has been developed in their laboratory for the computation of RF pulse waveforms for implementing non-Fourier encodings using high flip angles ( 90=A1) for high SNR scans. Third, at their facility, they have the operating capability for near real-time adaptive 2D MRI using a commercial MR system with the minor modification of an additional attached workstation.