标题： B1+ 磁场在金属植入物附近的映射使用快速自旋回波脉冲序列 显示英文标题

标题： B1+ mapping near metallic implants using turbo spin echo pulse sequences

摘要： 目的：提出一种基于快速自旋回波（TSE）脉冲序列获取的幅度图像的B1+映射技术，用于含有金属装置的身体部位成像。 理论和方法：为了编码潜在的B1+，获取了多个（两到四个）具有不同激励和重聚焦翻转角的TSE图像集。 为此，获取的信号强度与通过考虑精确序列参数求解布洛赫方程生成的模拟信号数据库进行了匹配。 检索到的B1+值在凝胶体模和无金属植入物及有金属植入物的人体受试者中，与梯度回波和自旋回波双角度方法以及供应商提供的基于turboFLASH的映射序列进行了验证。 结果：在没有金属的情况下，体模实验显示使用三个或四个翻转角集的所提出技术与参考双角度方法之间有很好的一致性。 在没有金属植入物的人体受试者中，使用三个或四个翻转角集的所提出技术与自旋回波双角度方法表现出极好的相关性。 在存在金属的情况下，体模和人体受试者显示参考技术的B1+估计范围较窄，而所提出的技术成功解决了金属附近的B1+。 在某些情况下，该技术与多光谱金属伪影减少序列结合使用，并成功应用于B1+匀场。 结论：所提出的技术能够在金属装置附近区域解析B1+值，克服了标准映射技术的易感性相关和范围狭窄的限制。 显示英文摘要

摘要： Purpose: To propose a B1+ mapping technique for imaging of body parts containing metal hardware, based on magnitude images acquired with turbo spin echo (TSE) pulse sequences. Theory and Methods: To encode the underlying B1+, multiple (two to four) TSE image sets with various excitation and refocusing flip angles were acquired. To this end, the acquired signal intensities were matched to a database of simulated signals which was generated by solving the Bloch equations taking into account the exact sequence parameters. The retrieved B1+ values were validated against gradient-recalled and spin echo dual angle methods, as well as a vendor-provided turboFLASH-based mapping sequence, in gel phantoms and human subjects without and with metal implants. Results: In the absence of metal, phantom experiments demonstrated excellent agreement between the proposed technique using three or four flip angle sets and reference dual angle methods. In human subjects without metal implants, the proposed technique with three or four flip angle sets showed excellent correlation with the spin echo dual angle method. In the presence of metal, both phantoms and human subjects revealed a narrow range of B1+ estimation with the reference techniques, whereas the proposed technique successfully resolved B1+ near the metal. In select cases, the technique was implemented in conjunction with multispectral metal artifact reduction sequences and successfully applied for B1+ shimming. Conclusion: The proposed technique enables resolution of B1+ values in regions near metal hardware, overcoming susceptibility-related and narrow-range limitations of standard mapping techniques.