Effect of BMI on image contrast in the hepatobiliary phase of Gd-EOB-DTPA-enhanced-MRI and its clinical application: a comparative study

Abstract

Background: Gadolinium-ethoxybenzyl-diethylenetriamine-pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) can detect more lesions through the image contrast of hepatobiliary phase. Body mass index (BMI) reflects the composition ratio of human tissue, which is an influencing factor of magnetic resonance image contrast. Meanwhile, Gd-EOB-DTPA is recommended to use the minimum dose when the diagnosis demands could be met. The aim of this paper was to investigate the effect of BMI on hepatobiliary phase image contrast and explore the feasibility of using low-dose Gd-EOB-DTPA to obtain good image contrast in hepatobiliary phase in patients with normal and lean BMI.Methods: Patients who had previously undergone Gd-EOB-DTPA-enhanced MRI (0.025 mmol/kg) were collected and divided into group A (BMI <24) and group B (BMI ≥24) according to Chinese BMI standards.Ratio of hepatic parenchymal signal to portal vein signal (LPR20) and hepatic parenchymal signal to splenic parenchymal signal (LSR20) in hepatobiliary phase (20 min after injection) were calculated. Patients with a BMI <24 who were about to receive Gd-EOB-DTPA-enhanced MRI were randomly divided into group C (0.0125 mmol/kg) and group D (0.025 mmol/kg). Image acquisition was performed at 10, 15, and 20 min after injection. LPR10, LPR15, LPR20 and LSR10, LSR15, LSR20 in corresponding phases were calculated.Results: In retrospective grouping study, compared with group B, group A's LPR20 was significantly higher [2.63 (2.42-3.00) vs. 2.22 (1.97-2.67); P<0.01]. In prospective grouping study, there were no differences in LPR15, LSR15, LPR20 and LSR20 between group C and group D. Intragroup comparison in each group showed that LPR15 (group C: 2.67±0.33; group D: 2.61±0.21) and LPR20 (group C: 2.74±0.37; group D: 2.72±0.27) were higher than LPR10 (group C: 2.19±0.18; group D: 1.94±0.17) (all P<0.01), while there were no changes between LPR15 and LPR20.Conclusions: Under conventional dose, hepatobiliary phase image contrast in patients with a BMI <24 was higher, which was mainly manifested in the high contrast between hepatic parenchyma and portal vein.For patients with a BMI <24, using a half conventional dose (0.0125 mmol/kg), good hepatobiliary phase image contrast can still be obtained at 15-20 min after administration, satisfying the diagnostic needs while also reducing the dosage of Gd-EOB-DTPA.