Magnetic resonance imaging features of intrahepatic bile duct adenoma: a 10-year retrospective study.

Background: Intrahepatic bile duct adenoma (BDA) is a rare tumor with limited understanding of its magnetic resonance imaging (MRI) features and clinical characteristics. This study aimed to analyze the MRI characteristics of BDA.

Methods: This retrospective study analyzed MRI findings and clinical profiles of 33 patients diagnosed with bile duct adenomas (BDA) at Zhongshan Hospital Fudan University from January 2014 to January 2024. MRI features and clinical data were reviewed and analyzed.

Results: A total of 36 lesions were identified among 33 patients, with 31 cases presenting as solitary lesions. The average diameter was 9.2 ± 3.1 mm, predominantly subcapsular, located near the liver capsule, with the majority exhibiting well-defined margins. On T1-weighted imaging (T1WI), lesions displayed hypointensity, while T2-weighted imaging (T2WI) was slightly hypointense in most cases, enhancing the visibility of the lesions. Apparent diffusion coefficient (ADC) values averaged (1.93 ± 0.51)×10⁻³ mm²/s, significantly higher than surrounding liver tissue (P < 0.001), suggesting unique tissue properties. Notably, BDA, as a hypervascular tumor, displayed rim and non-rim enhancement patterns, along with a tendency for persistent enhancement.

Conclusion: The MRI features of BDA included small lesions near the liver capsule, characterized by distinct morphology and enhancement patterns, alongside elevated ADC values that distinguish them from malignant hepatic lesions. The findings emphasize the importance of MRI in the accurate diagnosis and management of BDA.