A SEmi-Adiabatic matched-phase spin echo (SEAMS) PINS pulse-pair for B1 -insensitive simultaneous multislice imaging.
A SEmi-Adiabatic matched-phase spin echo (SEAMS) PINS pulse-pair for B1 -insensitive simultaneous multislice imaging.
复制标题
DOI：
10.1002/mrm.25654
复制
发表时间：
2016-02
影响因子：
3.3
通讯作者：
Balchandani P
中科院分区：
文献类型：
--
作者：
Feldman RE;Islam HM;Xu J;Balchandani P
同步多层（SMS）成像是一种功能强大的技术，可以减少解剖、功能和弥散加权磁共振成像的图像采集时间。在更高的磁场，如7特斯拉，增加射频（RF）场的不均匀性，功率沉积，和弛豫参数的变化，使SMS自旋回波成像具有挑战性。我们设计了一个绝热的180°功率独立于切片数（PINS）脉冲和一个匹配相位90° PINS脉冲来产生SEmi绝热匹配相位自旋回波（SEAMS）PINS序列来解决这些问题。我们使用绝热Shinnar Le-Roux（SLR）算法生成180°脉冲。然后使用180°脉冲的SLR多项式来创建匹配相位90°脉冲。对脉冲进行子采样以产生SEAMS PINS脉冲对，并在体模和体内验证该脉冲对的性能。模拟以及体模和体内结果表明，当在高于绝热阈值高达40%的RF幅度下工作时，SEAMS PINS脉冲对具有多切片能力并改善了B1不敏感性。与传统的自旋回波相比，本文提出的SEAMS PINS方法实现了具有改进的B1不敏感性的多切片自旋回波剖面。
Simultaneous multi-slice (SMS) imaging is a powerful technique that can reduce image acquisition time for anatomical, functional, and diffusion weighted magnetic resonance imaging. At higher magnetic fields, such as 7 Tesla, increased radiofrequency (RF) field inhomogeneity, power deposition, and changes in relaxation parameters make SMS spin echo imaging challenging. We designed an adiabatic 180° Power Independent of Number of Slices (PINS) pulse and a matched-phase 90° PINS pulse to generate a SEmi-Adiabatic Matched-phase Spin echo (SEAMS) PINS sequence to address these issues. We used the adiabatic Shinnar Le-Roux (SLR) algorithm to generate a 180° pulse. The SLR polynomials for the 180° pulse were then used to create a matched-phase 90° pulse. The pulses were sub-sampled to produce a SEAMS PINS pulse-pair and the performance of this pulse-pair was validated in phantoms and in vivo. Simulations as well as phantom and in vivo results, demonstrate multi-slice capability and improved B1-insensitivity of the SEAMS PINS pulse-pair when operating at RF amplitudes of up to 40% above adiabatic threshold. The SEAMS PINS approach presented here achieves multi-slice spin echo profiles with improved B1-insensitivity when compared to a conventional spin echo.