Radiology Department, Rakuwakai Marutamachi Hospital, Marutamachi-noboru, Shichihonmatsudori, Nakagyo-ku, Kyoto, Kyoto, 604-8401, Japan.
Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15, Kuramoto-cho, Toksuhima, Tokushima, 770-8509, Japan.
Radiol Phys Technol. 2020 Sep;13(3):268-275. doi: 10.1007/s12194-020-00579-y. Epub 2020 Aug 6.
We developed a novel magnetic resonance elastography (MRE) analysis method based on Fourier transform to assess the responsive characteristics for different tissue stiffness and degree of transmission of the vibration wave emanating from a passive driver during MRE. A phantom tissue study was conducted with an MRE sequence and vibration wave system using a clinical MR scanner. The phantom tissue consisted of two layers of agar: 0.75 wt% and 1.0 wt%. Phase-unwrapped images derived from acquired MRE phase images were used to generate a phase profile curve, with a line plotted for the phase-unwrapped images. Fourier transform was performed, and the peak value of the power spectrum was derived. The damping rate/ratio was calculated using the Hilbert transform of the phase profile. We found that the mean shear stiffness value of 1.0 wt% agar was higher than that of 0.75 wt% agar. The responsive frequency of the 0.75 wt% agar layer showed a wider range and the damping rate of the signal showed a higher value than the respective values of the 1.0 wt% agar layer. In conclusion, Fourier transform analysis of MRE enabled us to obtain more detailed information of the tissue characteristics and vibration-wave conditions.
我们开发了一种基于傅里叶变换的新型磁共振弹性成像（MRE）分析方法，用于评估在 MRE 期间来自被动驱动器的振动波的不同组织刚度和传输程度的响应特性。使用临床磁共振扫描仪的 MRE 序列和振动波系统进行了组织模型研究。组织模型由两层琼脂组成：0.75wt%和 1.0wt%。从采集的 MRE 相位图像中得出的解缠相位图像用于生成相位轮廓曲线，为解缠相位图像绘制一条线。进行傅里叶变换，并得出功率谱的峰值。使用相位轮廓的希尔伯特变换计算衰减率/比。我们发现 1.0wt%琼脂的平均剪切刚度值高于 0.75wt%琼脂。0.75wt%琼脂层的响应频率显示出更宽的范围，并且信号的衰减率显示出比 1.0wt%琼脂层的相应值更高的值。总之，MRE 的傅里叶变换分析使我们能够获得更详细的组织特征和振动波条件信息。
