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

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 (SI Norm ) of hemangiomas, liver parenchyma, and portal vein (PV) as well as contrast-to-norm ratio (C Norm ) 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 SI Norms of hemangiomas showed the highest value in the AP ( P < 0.05). The mean C Norms 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 SI Norms was lower in the TP ( P = 0.023). While the mean C Norms 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.