Influence of the Magnetic Field Strength on Image Contrast in Gd-EOB-DTPA-enhanced MR Imaging: Comparison between 1.5T and 3.0T

PURPOSE We quantitatively investigated hepatic enhancement in gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance (MR) imaging at 1.5T and 3.0T. METHODS A total of 40 patients who underwent Gd-EOB-DTPA-enhanced MR imaging were included in the study. Precontrast and hepatobiliary-phase images acquired at a low flip angle (FA, 12°) and hepatobiliary-phase images acquired at a high FA (30°) were analyzed. From these images, the liver-to-muscle signal intensity ratio (LMR) and liver-to-spleen signal intensity ratio (LSR) were estimated, and the contrast enhancement ratio (CER) was calculated from the liver signal, LMR, and LSR as the ratio of the low-FA hepatobiliary-phase value to the precontrast value. The coefficient of variance in the liver signal was determined to represent image noise. RESULTS LMR and LSR indicated similar image contrast between 1.5T and 3.0T. A higher FA provided larger LMRs and LSRs, and the degree of the FA-dependent increase was similar between 1.5T and 3.0T. CER did not differ significantly between 1.5T and 3.0T, regardless of the calculation method. A better correlation to CER calculated from the liver signal was found for the LMR-based CER values than for the LSR-based CER. The coefficient of variance in the liver signal was significantly smaller at 3.0T for precontrast and low-FA hepatobiliary-phase images, but not for high-FA hepatobiliary-phase images. CONCLUSION The indices of hepatic enhancement were similar between 1.5T and 3.0T, indicating that the magnetic field strength does not substantially influence image contrast after administration of Gd-EOB-DTPA.