3D-MRCP for evaluation of intra- and extrahepatic bile ducts: comparison of different acquisition and reconstruction planes

BACKGROUND: Magnetic resonance cholangiopancreatography (MRCP) is an established technique for the evaluation of intra- and extrahepatic bile ducts in patients with known or suspected hepatobiliary disease. However, the ideal acquisition and reconstruction plane for optimal bile duct evaluation with 3D technique has not been evaluated. The purpose of our study was to compare different acquisition and reconstruction planes of 3D-MRCP for bile duct assessment. METHODS: 34 patients (17f/17 m, mean age 41y) referred for MRCP were included in this prospective IRB-approved study. Respiratory-triggered 3D-T2w-MRCP sequences were acquired in coronal and axial plane. Coronal and axial MIP were reconstructed based on each dataset (resulting in two coronal and two axial MIP, respectively). Three readers in two sessions independently assessed the MIP, regarding visualization of bile ducts and image quality. Results were compared (Wilcoxon test). Intra- and interobserver variability were calculated (kappa-statistic). RESULTS: In case of coronal data acquisition, visualization of bile duct segments was significantly better on coronal reconstructed MIP images as compared to axial reconstructed MIP (p < 0.05). Regarding visualization, coronal MIP of the coronal acquisition were equal to coronal MIP of the axial acquisition (p > 0.05). Image quality of coronal and axial datasets did not differ significantly. Intra- and interobserver agreement regarding bile duct visualization were moderate to excellent (κ-range 0.55-1.00 and 0.42-0.85, respectively). CONCLUSIONS: The results of our study suggest that for visualization and evaluation of intra- and extrahepatic bile duct segments reconstructed images in coronal orientation are preferable. The orientation of the primary dataset (coronal or axial) is negligible.