Abstract
Purpose. To determine whether administration of gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA) and whether placement of the outer volume saturation bands significantly affect shimming and water suppression on hepatic MR spectroscopic prescanning. Method. Region of interest (ROI) of 2 cm × 2 cm × 2 cm was carefully positioned in the region of the middle portion of the right hepatic lobe. 32 patients were examined before and after administration of Gd-DTPA with and without outer-volume saturation bands. Linewidths (Full-Width Half-Maximum (FWHM)) and water suppression were obtained. A paired t-test for comparison of means was used. Results. (1) The group with the outer volume saturation bands demonstrated slightly better water suppression effect than the group without outer volume saturation bands before administration. (2) The group with the outer volume saturation bands demonstrated better water suppression effect than the group without outer volume saturation bands after administration. (3) Both shimming and water suppression effectswere decreased on enhanced MR spectroscopic prescanning (all P < 0.05). Conclusions. Placement of the outer volume saturation bands is helpful to improve water suppression both before and after contrast agent administration. Gd-DTPA exerts a slightly adverse effect (a statistically significant but clinically unimportant) on magnetic resonance spectroscopic prescanning at 3T.
Highlights
Magnetic resonance spectroscopy (MRS) is a noninvasive technique which is being increasingly applied to delineate biochemical changes of the liver
The aim of this study was to assess whether administration of gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA) and whether placement of the outer volume saturation bands significantly affects shimming and water suppression on hepatic MRS prescan adjustments on a 3.0T system
The group with the outer volume saturation bands demonstrated slightly better water suppression effect than the group without outer volume saturation bands before administration (94.0 ± 2.4%, 93.2 ± 2.8%, t = 3.763, P = 0.001)
Summary
Magnetic resonance spectroscopy (MRS) is a noninvasive technique which is being increasingly applied to delineate biochemical changes of the liver. The recent installation of higher field strength (3T) clinical magnets with multicoil arrays for the body offer new opportunities for performing body MR spectroscopy. The improved SNR can reduce acquisition times and the higher field strength provides better separation of resonances [6, 7]. As shimming improves the field homogeneity, linewidths become smaller and the spectroscopy resolution is enhanced. Strong resonance signals in prescans from the hydrogens in water molecules may interfere the signals from the lower concentration compounds of interest. The water signal may be suppressed to better discern the resonance signals of compounds of interest [7, 9, 10]
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