1H MR Spectroscopy of the Normal Human Brains: Comparison between Signa and Echospeed 1.5 T system

ABSTRACT

PURPOSE: To evaluate the usefulness and reproducibility of 1H MRS in different 1.5 T MR machines with different coils to compare the SNR, scan time and the spectral patterns in different brain regions in normal volunteers. MATERIALS AND METHODS: Localized 1H MR spectroscopy (1H MRS) was performed in a total of 10 normal volunteers (age; 20-45 years) with spectral parameters adjusted by the autoprescan routine (PROBE package). In all volunteers, MRS was performed in a three times using conventional MRS (Signa Horizon) with 1 channel coil and upgraded MRS (Echospeed plus with EXCITE) with both 1 channel and 8 channel coil. Using these three different machines and coils, SNRs of the spectra in both phantom and volunteers and (pre)scan time of MRS were compared. Two regions of the human brain (basal ganglia and deep white matter) were examined and relative metabolite ratios (NAA/Cr, Cho/Cr, and mI/Cr ratios) were measured in all volunteers. For all spectra, a STEAM localization sequence with three-pulse CHESS H2O suppression was used, with the following acquisition parameters TR=3.0/2.0 sec, TE=30 msec, TM=13.7 msec, SW=2500 Hz, SI=2048 pts, AVG=64/128, and NEX=2/8 (Signa/Echospeed). RESULTS: The SNR was about over 30% higher in Echospeed machine and time for prescan and scan was almost same in different machines and coils. Reliable spectra were obtained on both MRS systems and there were no significant differences in spectral patterns and relative metabolite ratios in two brain regions (p>0.05). CONCLUSION: Both conventional and new MRI systems are highly reliable and reproducible for 1H MR spectroscopic examinations in human brains and there are no significant differences in applications for 1H MRS between two different MRI systems.