Can we use 1{sup left}H MRS shimming values to obtain 31{sup left}P spectra?

摘要

The perfect shimming of 31{sup left}P magnetic resonance spectroscopy (MRS) is not easy in vivo. The purpose of this study was to examine the feasibility of using 1{sup left}H MRS shimming values to obtain 31{sup left}P 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 1{sup left}H and 31{sup left}P scans. A spin echo MRS sequence was utilized for both 1{sup left}H scans with a standard head coil and 31{sup left}P scans with a GE service coil. 1{sup left}H 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 1{sup left}H scan in x, y, z directions were copied to 31{sup left}P scan. A routine procedure of 31{sup left}P 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 1{sup left}H spectra and 31{sup left}P spectra were obtained for both phantom and volunteer studies. The 31{sup left}P spectra with 1{sup left}H MRS shimming values were similar with the 31{sup left}P spectra obtained with routine procedure. Lower SNRs of 31{sup left}P spectra were obtained in phantom with 1{sup left}H MRS shimming values, compared with routine procedure scan. Average SNR for Pi of 31{sup left}P spectra was 7.45:1 in the volunteer study with routine procedure, and 7.275:1 with 1{sup left}H MRS shimming values. 1{sup left}H MRS shimming values can be used to obtain useful 31{sup left}P spectra in a same sequence.