Evaluation of qualitative and quantitative imaging features of hepatic hemangiomas with and without pseudo-washout sign on gadoxetic acid-enhanced MRI: a descriptive and comparative study

Abstract

Background Hepatic hemangiomas are the most common benign liver tumors. It is important to know the imaging features of hemangiomas on gadoxetic acid (GA)-enhanced magnetic resonance imaging (MRI). Purpose To evaluate the qualitative and quantitative imaging features of hemangiomas on GA-enhanced MRI, and to compare imaging features of hemangiomas with and without pseudo-washout sign (PWS). Material and Methods We retrospectively included 93 cases of hemangioma that underwent GA-enhanced MRI. The presence of an enhancement pattern in the arterial phase (AP) and PWSs in the transitional phase (TP) were evaluated. Signal-to-norm ratios (SINorm) of hemangiomas, liver parenchyma, and portal vein (PV) as well as contrast-to-norm ratio (CNorm) were assessed. Additionally, hemangiomas with and without PWSs were defined as two separate subgroups, and imaging features were compared. Results Of the 93 cases of hemangiomas, 49 (52.6%) had PWSs in the TP. The mean SINorms of hemangiomas showed the highest value in the AP ( P < 0.05). The mean CNorms showed positive values in the AP, and gradually decreased ( P < 0.05). Hemangiomas with PWSs were significantly rapidly enhanced and smaller in size ( P < 0.05), and the mean SINorms was lower in the TP ( P = 0.023). While the mean CNorms showed a significant difference in the AP between subgroups ( P < 0.001), the enhancement pattern was equal to that of the PV. Conclusion When evaluating GA-enhanced MRI, radiologists should utilize quantitative measures in addition to qualitative assessment and should be aware that SI matching with PV in all phases can be a distinguishing finding in the diagnosis of hemangioma.