What are the imaging findings of hepatic hemangioma?

Hepatic hemangioma typically presents on imaging with regular shape, well-defined borders, uniform density or signal intensity, characteristic enhancement patterns, no significant mass effect, and clear demarcation from surrounding tissues. The details are as follows:

1. Regular shape with clear boundaries: On imaging, hepatic hemangiomas are usually round or oval in shape. Larger lesions may appear slightly irregular, but overall the contour is well-defined and clearly demarcated from adjacent normal liver tissue, without evidence of blurred infiltration.

2. Uniform density or signal intensity: On unenhanced CT scans, hemangiomas appear as hypodense lesions; on MRI, they show hypointense signals on T1-weighted images and hyperintense signals on T2-weighted images. The density or signal distribution is generally uniform. In larger hemangiomas, focal areas of abnormal density or signal may occur due to calcification or fibrosis, but overall uniformity remains predominant.

3. Characteristic enhancement pattern: On contrast-enhanced imaging, a typical "peripheral nodular enhancement with progressive centripetal fill-in" pattern is observed. During the arterial phase, peripheral nodular or ring-like enhancement appears, which gradually fills toward the center over time. By the venous or delayed phases, the entire lesion enhances and becomes nearly isodense or isointense compared to surrounding normal liver parenchyma.

4. Absence of significant mass effect: Most hepatic hemangiomas do not compress adjacent blood vessels, bile ducts, or liver parenchyma. Larger lesions may mildly displace neighboring structures, but there is no evidence of invasion or destruction. Liver contour and function are generally preserved.

5. Clear distinction from surrounding tissues: Whether on CT or MRI, hemangiomas can be clearly differentiated from adjacent liver tissue, blood vessels, and bile ducts. There are no signs of tissue adhesion or invasion, which helps differentiate them from malignant tumors.

Imaging features are crucial for diagnosing hepatic hemangioma. When the above characteristic findings are identified and correlated with clinical context, a preliminary diagnosis can be made. If findings are atypical, further investigations are required to confirm the diagnosis.