PARALLEL IMAGING PERFORMANCE AS A FUNCTION OF FIELD STRENGTH AN EXPERIMENTAL IN

并行成像性能作为场强函数的实验

• 批准号: 7601621
• 负责人: FLORIAN WIESINGER
• 金额: $ 4.72万
• 依托单位: UNIVERSITY OF MINNESOTA
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-06-01 至 2008-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7601621
• 关键词: Agreement; Behavior; Computer Retrieval of Information on Scientific Projects Database; Condition; Dependence; Ethanol; Funding; Grant; Image; Institution; Magnetic Resonance Imaging; Maps; N-methylformamide; Noise; Performance; Range; Research; Research Personnel; Resources; Sodium Chloride; Source; United States National Institutes of Health; Water; Work; base; decane; image reconstruction; magnetic field; radiofrequency

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. In this work, the dependence of parallel MRI performance on main magnetic field strength is experimentally investigated. Using the general framework of electrodynamic scaling, the B0-dependent behavior of the relevant radiofrequency fields at a single physical field strength of 7 T is studied. In the chosen implementation this is accomplished by adjusting the permittivity and conductivity of a homogeneous spherical phantom. With different mixing ratios of decane, ethanol, purified water, N-methylformamide, and sodium chloride, field strengths in the range of 1.5 to 11.5 T are mimicked. Based on sensitivity maps of an eight-coil receiver array, the field-dependent performance of parallel imaging is assessed in terms of the geometry factor g, which reflects noise enhancement in parallel imaging reconstruction. At low field strengths the SNR penalty was nearly independent of B0 and favorably low for 1D reduction factors up to between 3 and 4. At higher field strengths the transition between favorable and prohibitive parallel imaging conditions was found to shift toward higher feasible reduction factors. These findings are in good agreement with previous theoretical predictions. From this agreement it is concluded that parallel MRI at high B0 benefits specifically from onsetting far-field behavior of the involved radiofrequency fields.

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 在这项工作中，并行MRI性能的主磁场强度的依赖关系进行了实验研究。使用电动标度的一般框架，在一个单一的物理场强度为7 T的相关射频场的B 0依赖的行为进行了研究。在所选择的实施方式中，这是通过调整均匀球形体模的介电常数和电导率来实现的。通过癸烷、乙醇、纯化水、N-甲基甲酰胺和氯化钠的不同混合比例，模拟了1.5至11.5 T范围内的场强。基于八线圈接收器阵列的灵敏度图，并行成像的场依赖性能的几何因子g，这反映了在并行成像重建的噪声增强方面进行评估。在低场强下，SNR损失几乎与B 0无关，并且对于高达3至4之间的1D缩减因子有利地较低。在更高的场强之间的过渡有利和禁止的并行成像条件被发现转向更高的可行的减少因素。这些发现与以前的理论预测吻合得很好。从该协议可以得出结论，在高B 0的并行MRI受益于所涉及的射频场的远场行为。