Phase coherent averaging in magnetic resonance Spectroscopy using interleaved navigator scans: Compensation of motion artifacts and magnetic field instabilities
Phase coherent averaging in magnetic resonance Spectroscopy using interleaved navigator scans: Compensation of motion artifacts and magnetic field instabilities
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DOI：
10.1002/mrm.10174
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发表时间：
2002-06-01
影响因子：
3.3
通讯作者：
Hennig, F
中科院分区：
文献类型：
--
作者：
Thiel, T;Czisch, M;Hennig, F
H-1磁共振波谱（MRS）中的频谱质量受到采集过程中时间信号不稳定性的强烈影响。这些不稳定性的一个原因是硬件缺陷，例如，超导磁体中主磁场的漂移。这是特别关注的高场系统中的场稳定性的规格是接近的光谱线宽。伪影的第二个主要潜在来源，特别是在临床MRS中，是患者运动。使用单个采集的相位循环平均的标准采集方案，长期影响（场漂移）以及较短时间尺度上的变化（运动）会严重降低光谱质量。本文提出的体积选择性MRS的新技术是基于在代谢物采集的恢复时间期间导航信号的额外交错采集。它通过代谢物和导航信号的去卷积来校正时间信号不稳定性。这导致相位校正的个体代谢物扫描，并且在求和时导致相位相干平均方案。交错导航器采集不需要任何用户交互或监督，同时保持序列效率。
The quality of spectra in H-1 magnetic resonance spectroscopy (MRS) is strongly affected by temporal signal instabilities during the acquisition. One reason for these instabilities are hardware imperfections, e.g., drifts of the main magnetic field in superconducting magnets. This is of special concern in high-field systems where the specification of the field stability is close to the spectral linewidth. A second major potential source of artifacts, particularly in clinical MRS, is patient motion. Using standard acquisition schemes of phase-cycled averaging of the individual acquisitions, long-term effects (field drifts) as well as changes on a shorter time scale (motion) can severely reduce spectral quality. The new technique for volume-selective MRS presented here is based on the additional interleaved acquisition of a navigator signal during the recovery time of the metabolite acquisition. It corrects for temporal signal instabilities by means of a deconvolution of the metabolite and the navigator signal. This leads to phase-corrected individual metabolite scans and upon summation to a phase-coherent averaging scheme. The interleaved navigator acquisition does not require any user interaction or supervision, while sequence efficiency is maintained.