Investigating the regional effect of the chemical shift displacement artefact on the J-modulated lactate signal at ultra high-field.
Investigating the regional effect of the chemical shift displacement artefact on the J-modulated lactate signal at ultra high-field.
复制标题
研究化学位移位移伪影对超高场 J 调制乳酸信号的区域影响。
DOI：
10.1002/nbm.4440
复制
发表时间：
2021
影响因子：
2.9
通讯作者：
Fernandes CC
中科院分区：
文献类型：
--
作者：
Fernandes CC
本工作旨在显示分析模型在超高场乳酸检测中优化STEAM序列定时参数的适用性。考虑了弱耦合自旋系统在三个施加场梯度的方向上化学位移伪影对J调制信号的影响，并使用乘积算符形式获得了激发体积每个隔室中信号调制的表达式。该模型的有效性在7 T的体模和采集优化参数进行了实验证明健康志愿者。在TE = 144 ms和优化的混合时间以及TE = 288 ms下获得的光谱显示在正常人脑中容易检测到的乳酸峰。此外，使用较长TE的采集导致具有较少脂质/大分子污染的光谱。这里所示的模拟表明，所提出的分析模型适用于正确预测所得的乳酸信号。通过优化参数，可以使用具有足够信噪比的简单序列来可靠地区分健康大脑中的乳酸与重叠共振。
The present work aims to show the applicability of an analytical model for the optimisation of the STEAM sequence timing parameters for lactate detection at ultra high‐field. The effects of the chemical shift displacement artefact on the J‐modulated signal for a weakly‐coupled spin system were considered in the three applied directions of field gradients and the product operator formalism was used to obtain expressions for the signal modulation in each compartment of the excited volume. The validity of this model was demonstrated experimentally at 7 T in a phantom and acquisitions with optimised parameters were performed on a healthy volunteer. The spectra acquired with TE = 144 ms with the optimised mixing time and TE = 288 ms showed easily detectable lactate peaks in the normal human brain. Additionally, the acquisition with the longer TE resulted in a spectrum with less lipid/macromolecular contamination. The simulations shown here demonstrated that the proposed analytical model is suitable for correctly predicting the resulting lactate signal. With the optimised parameters, it was possible to use a simple sequence with sufficient signal‐to‐noise ratio to reliably distinguish lactate from overlapping resonances in a healthy brain.