SIMULTANEOUS MAPPING OF B1 AND B0 FIELDS AT 7 TESLA

7 特斯拉下 B1 和 B0 场的同步测绘

• 批准号: 8169085
• 负责人: MARK A ELLIOTT
• 金额: $ 1.73万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-06-01 至 2011-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8169085
• 关键词: Calibration; Computer Retrieval of Information on Scientific Projects Database; Equation; Funding; Grant; Heterogeneity; Institution; Magnetic Resonance Imaging; Maps; Measures; Methods; Penetration; Perfusion; Research; Research Personnel; Resources; Source; Spin Labels; System; United States National Institutes of Health; 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. Endogenous MRI perfusion methods such as ASL require accurate calibration of the transmitted radiofrequency magnetic field (B1) in order to achieve precise inversion of the labeled spins. This is especially necessary at high main magnetic field (B0) strengths, where wavelength and penetration effects create heterogeneous B1 fields as well as high local SAR effects. B1 heterogeneity at high field is further compounded by increased B0 inhomogeneity, which can result in underestimation of the transmit B1 field by standard methods, including AFI. When the degree of off-resonance is appreciable compared to the B1 amplitude, then the nominal flip angle measured by the AFI method is less than the actual nutation produced by the B1 field. In order to obtain the correct B1 field strength, the B0 field must also be measured, and the complete system described by the Bloch equations can be solved for the actual flip angle, which is the true measure of the B1 field.

该副本是利用众多研究子项目之一 由NIH/NCRR资助的中心赠款提供的资源。子弹和 调查员（PI）可能已经从其他NIH来源获得了主要资金， 因此可以在其他清晰的条目中代表。列出的机构是 对于中心，这不一定是调查员的机构。 内源性MRI灌注方法（例如ASL）需要对传输的准确校准 射频磁场（B1），以实现标记的自旋的精确反转。这 在高主磁场（B0）强度下特别需要 渗透效应会产生异质的B1场以及局部较高的SAR效应。 B1 B0不均匀性增加了高场的异质性，这可以 通过包括AFI在内的标准方法低估了发射B1场的低估。什么时候 与B1振幅相比，离子的程度是可观的，然后是标称翻转 通过AFI方法测量的角度小于B1场产生的实际营养。在 为了获得正确的B1场强度，还必须测量B0场，然后测量 Bloch方程描述的完整系统可以解决实际的翻转角度， 是B1场的真实度量。