Gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid as an intrabiliary contrast agent: preliminary assessment

We assessed the added efficacy of gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (gadolinium-EOB) in depicting biliary structures compared with T2-weighted MR cholangiopancreatography (T2-MRCP) and measured reviewer preference and willingness-to-pay for the added value of biliary contrast. Ten patients prospectively underwent T2-MRCP and gadolinium-EOB-enhanced MR cholangiography (EOB-MRC). Three radiologists reviewed the unpaired, then the paired, examinations, rating biliary visualization using a 5-point scale. The common bile, right and left hepatic ducts, and second-order branches were evaluated. Improved biliary visualization using paired over unpaired tests indicated the added value of contrast media. Kappa values measured interobserver reliability. A regression model controlling for fixed effects due to reviewer and subject correlation quantified improvement in ratings attributable to paired review. Average visualization ratings for unpaired review of EOB-MRC were the following: common bile duct, 3.3; right hepatic duct, 2.7; left hepatic duct, 2.5; second-order branches, 1.4. Average visualization ratings for unpaired review of T2-MCRP were the following: common bile duct, 3.4; right hepatic duct, 1.8; left hepatic duct, 2.2; second-order branches, 0.9. Ratings improved using paired tests over EOB-MRC and T2-MRCP for all structures (p < 0.001) except for T2-MRCP common bile duct ratings (p > 0.05). Agreement was moderate to good except for EOB-MRC common bile duct ratings. Paired review improved ratings (chi(2) < 0.0001) over T2-MRCP alone by 1.05 and over EOB-MRC alone by 0.68. Despite significant improvement, reviewers preferred unpaired T2-MRCP (53%) over unpaired EOB-MRC (17%) or paired tests (30%). Reviewers were willing to pay $25 (median) for gadolinium-EOB. Combining T2-MRCP and EOB-MRC significantly improved biliary visualization over each test alone. However, improvement was small, and the perceived added value of gadolinium-EOB was modest.