Effects of Contrast Agent on Water Suppression and Shimming of Kidney Single-Volume Proton MR Spectroscopy at 3.0T

Abstract

The aim of this study was to determine whether the administration of gadolinium diethylenetriamine penta-acetic acid (Gd-DTPA) significantly affects shimming and water suppression on kidney magnetic resonance spectroscopic prescanning and whether the impact of shimming and water suppression is changed with time after intravenous administration on a 3.0-T system. Forty patients (two patients were excluded from analysis because of motion) were examined before and after the administration of Gd-DTPA (the interval between the right and left kidneys was approximately 40 seconds). Regions of interest were carefully positioned in the region of the corresponding location of both kidneys separately. Line widths (full width at half maximum) and water suppression were obtained. A paired t test for comparison of means was used. In addition, repeat measurements with a shorter time interval (obtained 120-130 seconds after the injection) and a longer time interval (obtained 150-160 seconds after the injection) were performed in five patients in the same regions of interest of the right kidney. Sequential ¹H magnetic resonance spectroscopic prescanning in the same region of interest was performed in one patient. The left kidney had slightly better shimming and water suppression effects than the right kidney after contrast agent administration (all P values < .01). The limiting resolution of both shimming and water suppression effects was decreased on enhanced images in both kidneys (all P values < .01). The longer time interval group had better shimming and water suppression effects than the shorter time interval group (all P values < .01). After the administration of Gd-DTPA in one patient, sequential values of shimming and water suppression in the right and left kidneys, respectively, were 13 Hz and 97% and 12 Hz and 97% prior to the examination, 34 Hz and 86% and 30 Hz and 88% at 5 minutes, 32 Hz and 89% and 27 Hz and 90% at 10 minutes, 28 Hz and 91% and 24 Hz and 91% at 15 minutes, and 24 Hz and 92% and 20 Hz and 92% at 25 minutes. Gd-DTPA exerts adverse effects on water suppression and shimming, both of which show a trend of becoming well gradually with time extension after the injection of Gd-DTPA. This phenomenon limits the diagnostic use of kidney magnetic resonance spectroscopy performed immediately after contrast-enhanced magnetic resonance imaging.