PARALLEL TRANSMIT ENABLED PULSE SEQUENCE DEVELOPMENT FOR HIGH FIELD MRI

这个子项目是许多利用资源的研究子项目之一 由NIH/NCRR资助的中心拨款提供。子项目的主要支持 而子项目的主要调查员可能是由其他来源提供的， 包括其它NIH来源。 列出的子项目总成本可能 代表子项目使用的中心基础设施的估计数量， 而不是由NCRR赠款提供给子项目或子项目工作人员的直接资金。 高场MRI系统有潜力实现超高空间分辨率成像，提供增强的敏感性， 对比度和改进的光谱学中的化学物种辨别。然而，高场MRI也对磁共振成像技术提出了挑战。 射频（RF）激励均匀性降低的形式。这表现为图像中的阴影伪影， 定量成像具有挑战性。多发射射频脉冲设计的最新发展提供了以下可能性： 通过使用多个并行发射器来利用RF在激励k空间中激励复杂图案来克服这一点，以及 在多个通道中产生梯度脉冲，从而在感兴趣区域上产生净均匀激励场。之一 这种RF脉冲设计的关键输入是所谓的B1图，即激励场的空间映射，其是时间 消费步骤。因此，准确但快速的B1映射是在高场生成无阴影图像的关键。 要了解卢卡斯中心正在进行的其他项目，请访问http://rsl.stanford.edu/ （卢卡斯年度报告和 ISMRM 2011摘要）

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. High field MRI systems have the potential to enable ultra high spatial resolution imaging, provide enhanced susceptibility contrast and improved chemical species discrimination in spectroscopy. However high field MRI also poses challenges in the form of decreased radio frequency (RF) excitation homogeneity. This manifests as shading artifacts in the images, making quantitative imaging challenging. Recent developments in multi-transmit radiofrequency pulse design offer a possibility of combating this by using multiple parallel transmitters to excite a complex pattern in excitation k-space using RF and gradient pulses in multiple channels that results in a net uniform excitation field across the region of interest. One of the key inputs to such an RF pulse design is the so-called B1 map, a spatial mapping of the excitation field, which is a time consuming step. Accurate but fast B1 mapping is hence key in generating shading-free images at high fields. To read about other projects ongoing at the Lucas Center, please visit http://rsl.stanford.edu/ (Lucas Annual Report and ISMRM 2011 Abstracts)