频率校正方法在活体肝脏^1H磁共振波谱中的应用

In vivo ^1H-MRS of Liver： The Effects of Frequency Correction

主要探讨频率校正技术在活体肝脏1H磁共振波谱的应用价值.肝脏单体素1H磁共振波谱采用PRESS序列,频率位移分析和校正基于频域谱的残余水峰.结果表明,5例健康志愿者频率变化的标准偏差为7.92±4.12Hz;采用频率校正方法处理后,残余水峰和脂肪峰(-(CH2)n-)的谱线明显变窄,信噪比得到一定程度的改善.因此频率校正技术可以改善活体肝脏1H磁共振波谱的谱质量,从而增加磁共振波谱在肝脏病变评价中的准确性.

The aim of this work was to evaluate the effect of frequency correction on reducing the motion artifacts in in vivo ^1H magnetic resonance spectroscopy of liver. Single-voxel ^1H spectra of the middle region of human liver were acquired using a frame-by- frame PRESS technique at 1.5 Tesla. Frame-by-frame variations in the frequency of the residual water signal were analyzed and used for retrospective correction of the frequency shifting of individual spectra prior to averaging. The results showed that the standard deviation of the frequency variations was 7.92±4.12 Hz （n=5）. Compared to the averaged spectra without frequency correction, the averaged spectra with frequency correc- tion showed significantly increased signal-to-noise ratios and narrower linewidth for both the lipid （-（CH2）n-） signal and the residual water signal. This work demonstrated that the frequency correction technique can he used to improve the quality of in vivo ^1H spectra of liver.