Fluid-fluid levels within focal hepatic lesions: Imaging appearance and etiology

Purpose: To report our experience with fluid-fluid levels within focal hepatic lesions and determine if this finding indicates a specific diagnosis. Materials and methods: We reviewed our experience with eight patients with focal hepatic lesions that showed fluid-fluid level on cross-sectional imaging. Seven CT scans, four MR examinations, and four sonograms were reviewed. The hepatic lesions included metastases (four patients), biliary cystadenoma (two patients), cavernous hemangioma (one patient), and hematoma (one patient). A histologic diagnosis was made in all cases. Results: Fluid-fluid levels were found in both malignant and benign focal hepatic lesions. Fluid-fluid levels were seen on six CT scans, four MR examinations and on none of the four sonograms. Radiologic-pathologic correlation showed that fluid-fluid levels corresponded to internal hemorrhage in all but one case. In the case of cavernous hemangioma, a fluid-fluid level was found to correspond to a sedimentation effect within a large vascular space. Conclusion: Fluid-fluid levels in focal hepatic lesions do not indicate a specific diagnosis but can be seen in both malignant and benign conditions affecting the liver.