O-Space Imaging - Accelerating MRI with Z2 Gradient Encoding

O-Space Imaging - 使用 Z2 梯度编码加速 MRI

• 批准号: 8639688
• 负责人: R Todd Constable
• 金额: $ 49.79万
• 依托单位: YALE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-09-30 至 2017-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8639688
• 关键词: Acceleration; Amplifiers; Applications Grants; Area; Back; Clinical; Clinical Research; Complement; Coupling; Data; Development; Elements; Head; Hour; Human; Image; Improve Access; Joints; Lead; Location; Magnetic Resonance Imaging; Methodology; Methods; Morphologic artifacts; Names; Patients; Performance; Phase; Physiologic pulse; Positron-Emission Tomography; Process; Public Health; Relative (related person); Research; Resolution; Sampling; Scanning; Scheme; Shapes; Solutions; Speed; Structure; Surface; Testing; Three-Dimensional Imaging; Time; Work; base; clinical practice; clinically relevant; cost; data acquisition; design; improved; innovation; magnetic field; next generation; novel strategies; public health relevance; radiofrequency; research study; theories

DESCRIPTION (provided by applicant): Recent improvements in parallel-imaging performance in MRI have been driven by the use of greater numbers of radiofrequency (RF) surface coils placed in an array so as to maximize the ability to unwrap the aliasing that occurs along a linear phase encode direction when the data is undersampled (accelerated). This approach to acceleration is maturing and providing diminishing returns as more and more receiver coils are used, due to coil-coupling problems, which dominate as the size of the coil elements decreases and the number of elements increases. This proposal is aimed at providing further acceleration in parallel imaging through a reassessment of the magnetic field gradients used for spatial encoding. By considering the joint contributions of spatial encoding of the receiver coils and the magnetic fields, we can develop a more efficient approach to spatial encoding. A simple solution to this problem is to use a nonlinear magnetic field gradient, the Z2 gradient. Such a gradient shape (relative to linear X and Y gradients) provides spatial encoding more complementary to that provided by the receiver coils. The approach we have developed, O-space imaging - so named because the isofrequency contours during the readout are in the shape of concentric rings rather than columns as with a linear X-readout - was initially introduced by us in 2010. The theory and preliminary data generated using a small Z2-gradient insert on a clinical MRI scanner have provided evidence that substantial increases in acceleration can be achieved with modest numbers of receiver coils. This proposal is aimed at scaling these tests up to human imaging levels using a head-insert Z2-gradient coil fully integrated with the Siemens 3T Trio scanner. The O-space imaging approach is a general acceleration method that can be adapted to almost any pulse sequence. We will test, in phantom and human imaging experiments, the capabilities of O-space imaging to outperform conventional SENSE imaging using modified spin echo, fast spin echo and 3D imaging sequences at a range of resolutions and acceleration factors and using both an 8-channel and a 32-channel Tx/Rx coil. The end result of this work will be a demonstration of the viability of this new methodology for providing highly accelerated parallel imaging. The project is highly innovative and by reconsidering the spatial encoding gradients it opens up a new area of research in MR accelerated imaging. The project is significant in that providing an acceleration factor of 2 or more to a number of standard clinical MR pulse sequences could provide a huge benefit to public health, allowing for higher resolution, or more detailed examinations, and significantly increased throughput improving access to MRI and/or lowering per-scan costs.

描述（由申请人提供）：MRI 并行成像性能的最新改进是通过使用放置在阵列中的更多射频 (RF) 表面线圈来推动的，以便最大限度地解开数据欠采样（加速）时沿线性相位编码方向出现的混叠的能力。随着越来越多的接收器线圈的使用，这种加速方法正在成熟，并且由于线圈耦合问题（随着线圈元件尺寸的减小和元件数量的增加而占主导地位），其回报递减。该提案旨在通过重新评估用于空间编码的磁场梯度来进一步加速并行成像。通过考虑接收器线圈和磁场的空间编码的共同贡献，我们可以开发一种更有效的空间编码方法。该问题的一个简单解决方案是使用非线性磁场梯度，即 Z2 梯度。这种梯度形状（相对于线性X和Y梯度）提供了与接收器线圈所提供的空间编码更加互补的空间编码。我们开发的 O 空间成像方法（如此命名是因为读出期间的等频轮廓是同心环的形状，而不是像线性 X 读出那样的柱形），最初由我们于 2010 年引入。使用临床 MRI 扫描仪上的小型 Z2 梯度插入物生成的理论和初步数据提供了证据，表明通过适度数量的接收线圈可以实现加速度的大幅增加。该提案旨在使用与西门子 3T Trio 扫描仪完全集成的头插入式 Z2 梯度线圈将这些测试扩展到人类成像水平。 O空间成像方法是一种通用的加速方法，可以适应几乎任何脉冲序列。我们将在体模和人体成像实验中，使用改进的自旋回波、快速自旋回波和 3D 成像序列，在一系列分辨率和加速因子下，并使用 8 通道和 32 通道 Tx/Rx 线圈，测试 O 空间成像优于传统 SENSE 成像的能力。这项工作的最终结果将证明这项工作的可行性 提供高度加速并行成像的新方法。该项目具有高度创新性，通过重新考虑空间编码梯度，开辟了 MR 加速成像研究的新领域。该项目的意义重大，因为为许多标准临床 MR 脉冲序列提供 2 或更高的加速因子可以为公众健康带来巨大好处，允许更高分辨率或更详细的检查，并显着提高吞吐量，改善 MRI 的访问和/或降低每次扫描成本。