我们能否使用氢质子磁共振波谱（1H MRS）匀场值来获取磷磁共振波谱（31P spectra）？

Wu R H, Guo G, Zhang Y P, Tran H, terBrugge K, Mikulis D

Dept. of Med. Imaging, Shantou Univ. Med. Coll., China.

Conf Proc IEEE Eng Med Biol Soc. 2006;2006:1873-6. doi: 10.1109/IEMBS.2006.260792.

The perfect shimming of 31P magnetic resonance spectroscopy (MRS) is not easy in vivo. The purpose of this study was to examine the feasibility of using 1H MRS shimming values to obtain 31P spectra in a same sequence. Both phantom and volunteer studies were carried out in this study. Phantom was a sphere filled with physiological metabolites of brain. In vivo study was performed on 4 healthy volunteers. The studies were performed on a 3-T GE scanner. A same localizer and a same cursor were used for both 1H and 31P scans. A spin echo MRS sequence was utilized for both 1H scans with a standard head coil and 31P scans with a GE service coil. 1H scan was performed using first and automatic shimming and water linewidth (FWHM) of 3 Hz for phantom and 5 Hz for the volunteer were obtained. Shimming values of 1H scan in x, y, z directions were copied to 31P scan. A routine procedure of 31P scan without value coping was also performed. Spectra were analyzed using SAGE/IDL program. Signal to noise ratio (SNR) was defined as the ratio of the signal height / maximum noise height. Good 1H spectra and 31P spectra were obtained for both phantom and volunteer studies. The 31P spectra with 1H MRS shimming values were similar with the 31P spectra obtained with routine procedure. Lower SNRs of 31P spectra were obtained in phantom with 1H MRS shimming values, compared with routine procedure scan. Average SNR for Pi of 31P spectra was 7.45:1 in the volunteer study with routine procedure, and 7.275:1 with 1H MRS shimming values. 1H MRS shimming values can be used to obtain useful 31P spectra in a same sequence.

在体内实现31P磁共振波谱（MRS）的完美匀场并非易事。本研究的目的是检验在同一序列中使用1H MRS匀场值来获取31P波谱的可行性。本研究同时进行了体模和志愿者研究。体模是一个充满脑生理代谢物的球体。对4名健康志愿者进行了体内研究。研究在一台3-T的GE扫描仪上进行。1H和31P扫描均使用相同的定位器和相同的光标。1H扫描采用自旋回波MRS序列，使用标准头部线圈，31P扫描使用GE服务线圈。对体模进行1H扫描时采用首次自动匀场，获得的水线宽（半高宽）对于体模为3 Hz，对于志愿者为5 Hz。将1H扫描在x、y、z方向的匀场值复制到31P扫描中。还进行了一次不复制值的31P扫描常规操作。使用SAGE/IDL程序对波谱进行分析。信噪比（SNR）定义为信号高度与最大噪声高度之比。体模和志愿者研究均获得了良好的1H波谱和31P波谱。采用1H MRS匀场值的31P波谱与常规操作获得的31P波谱相似。与常规操作扫描相比，采用1H MRS匀场值时体模中31P波谱获得的SNR较低。在志愿者研究中，采用常规操作时31P波谱中无机磷（Pi）的平均SNR为7.45:1，采用1H MRS匀场值时为7.275:1。1H MRS匀场值可用于在同一序列中获取有用的31P波谱。