Effect of shimming on water suppression and metabolites concentrations of 3.0T proton spectrum / 中国医学影像技术

ABSTRACT

Objective To observe the effect of full width half max (FWHM) on spectra signal-to-noise ratio (SNR), NAA/Cr, Cho/Cr and water suppression at 3.0T MR. Methods GE Signa Excite HD 3.0T MR scanner with 8 channel phrased-array head and neck coil was used. The respective study of liver 1H-MRS was performed using PRESS sequence. A total of 49 spectrums were obtained with parameters of TR 1500 ms, TE 30 ms, NSA 128. FWHM and water suppression were recorded automatically and the subjects were divided into better shimming group (FWHM<10 Hz) and worse shimming group (FWHM≥10 Hz). Independent t test was used to analyze the Cr_SNR, NAA/Cr, Cho/Cr, water suppression and volume of interest (VOI). Results Compared with worse shimming group, better shimming group could provide better Cr_SNR (t=5.976, P<0.001), higher NAA/Cr (t=2.469, P=0.017), lower Cho/Cr (t=-4.460, P<0.001) and smaller VOI (t=3.862, P<0.001). Conclusion When single voxel proton spectroscopy of head is adopted with 3.0T MR, small VOI is easy to achieve effective shimming, and better shimming is helpful to improve SNR, the ratio of main metabolites as well as water suppression.