Can bile excretion on Gd-EOB-MRI be used as a visual criterion for the hepatobiliary phase?

To determine whether visually observed biliary excretion of gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) can be used to assess contrast adequacy of hepatobiliary phase (HBP) images. Images of 121 patients undergoing Gd-EOB-DTPA-enhanced magnetic resonance imaging were used. Adequate HBP images were defined as a quantitative liver–spleen contrast ratio (Q-LSC) ≥ 1.5. Visual evaluation was performed to determine if an adequate HBP image could be obtained based on the presence or absence of bile excretion. Common bile duct–paravertebral contrast (CPC) was used to assess the degree of bile excretion, the albumin–bilirubin (ALBI) grade was used to assess liver reserve, and the Q-LSC was used to assess HBP image contrast. The results were used to quantitatively evaluate the relationships of the degree of bile excretion with HBP image contrast and liver reserve. The cases correctly determined by visual evaluation via bile excretion were 80 (66.1%) at HBP 10 min after injection and 89 (73.6%) at HBP 20 min after injection. Among cases with Q-LSC ≥ 1.5 indicating bile excretion, there were 33 cases at HBP 10 min after injection and 86 cases at HBP 20 min after injection. Furthermore, among cases with Q-LSC < 1.5, indicating no bile excretion, there were 47 cases at HBP 10 min after injection and 3 cases at HBP 20 min after injection. Visually observed biliary excretion of Gd-EOB-DTPA is not a criterion for adequate HBP image contrast.