Respiration-induced B0 field fluctuation compensation in balanced SSFP:: Real-time approach for transition-band SSFP fMRI
Respiration-induced B0 field fluctuation compensation in balanced SSFP:: Real-time approach for transition-band SSFP fMRI
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DOI：
10.1002/mrm.20879
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发表时间：
2006-05-01
影响因子：
3.3
通讯作者：
Pauly, JM
中科院分区：
文献类型：
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作者：
Lee, J;Santos, JM;Pauly, JM
在功能磁共振成像（fMRI）中，由呼吸引起的共振频率偏移是生理噪声的主要来源。在过渡带SSFP fMRI中，呼吸引起的共振偏移不仅增加了噪声干扰，还移动了激活带。这导致对比度噪声比（CNR）的降低和在实验期间改变对比度水平的可能性。提出了一种新的实时补偿呼吸引起的共振偏移频率的方法。该方法利用自由感应衰减（FID）相位信息来测量谐振偏移。为了补偿，可以通过改变发射RF脉冲和接收器相位来在真实的时间中更新谐振频率以跟踪测量的偏移。结果显示，与未补偿的实验相比，呼吸频带中的信号功率降低，并且具有较高Z分数的激活体素的数量增加。
In functional MRI (fMRI) the resonance frequency shift induced from respiration is a major source of physiological noise. In transition-band SSFP fMRI the respiration-induced resonance offset not only increases noise interference, it also shifts the activation band. This leads to a reduction in the contrast-to-noise ratio (CNR) and the potential for varying contrast levels during the experiment. A novel real-time method that compensates for the respiration-induced resonance offset frequency is presented. This method utilizes free induction decay (FID) phase information to measure the resonance offset. For compensation, one can update the resonant frequency in real time by changing the transmit RF pulse and receiver phases to track the measured offset. The results show decreased signal power in the respiration frequency band and increased numbers of activated voxels with higher Z-scores compared to uncompensated experiments.