Imaging findings of primary hepatic angiosarcoma on gadoxetate disodium-enhanced liver MRI: comparison with hepatic haemangiomas of similar size

Aim: To describe imaging characteristics of primary hepatic angiosarcoma on gadoxetate disodium-enhanced dynamic magnetic resonance imaging (MRI) and to determine features that differentiate angiosarcomas from similar-sized haemangiomas. Materials and methods: The study included 15 patients with hepatic angiosarcomas and 35 patients with size-matched hepatic haemangiomas who underwent gadoxetate disodium-enhanced liver MRI. The number, size, growth pattern, signal intensity (SI) characteristics, and SI changes on dynamic scans were evaluated and compared between the two entities. Results: Overall, hepatic angiosarcomas significantly more often showed lesion multiplicity (86.7%), capsular retraction (40%), prominent intratumoural vessels (66.7%), vascular invasion (20%), heterogeneous SI on T2-weighted (100%) and hepatobiliary phase images (80%), and intralesional haemorrhage (60%, all p<0.05). On dynamic scans, angiosarcomas demonstrated enhancing foci of irregular or rim-like nodular/linear or bizarre (86.7%) shapes, with centrifugal or bizarre patterns of progressive enhancement (53.3%). Enhancement of angiosarcomas was less than that of the blood pool on visual grading, but the enhancement curves followed that of the aorta. Regardless of size, angiosarcomas showed heterogeneous T2 SI, intratumoural haemorrhage, and heterogeneity during the hepatobiliary phase, whereas these findings were more common in haemangiomas >6 cm in diameter. Conclusion: Gadoxetate disodium-enhanced dynamic liver MRI is capable of depicting vascular hallmarks of hepatic angiosarcomas. Heterogeneous SI on T2-weighted and hepatobiliary phase images, multiplicity, and an enhancement curve following that of the aorta are also distinctive features that differentiate angiosarcomas from haemangiomas.