Novel and Specific MRI Features Indicate the Clinical Features of Patients With Rare Hepatic Tumor Epithelioid Hemangioendothelioma

Abstract

Objective: To investigate the MRI features and clinical significance of hepatic epithelioid hemangioendothelioma (HEHE).

Methods: Clinical records and MRI findings were retrospectively evaluated in nine HEHE patients from May 2010 to January 2020.

Result: There were 121 lesions in nine patients with a predominantly peripheral distribution. Five lesions (4.13%) in two patients (22.22%) had evidence of capsular retraction, and three patients had lung metastasis (33.33%). Dynamic contrast-enhanced MRI showed progressive enhancement, mainly in two ways: ring enhancement with hypovascularity in four patients (44.44%) and ring enhancement with hypervascularity in five patients (55.56%). Imaging demonstrated a multilayer ring appearance, which was typically observed on T2-weighted imaging (T2WI). The most common appearance consisted of two layers of varying signal, with some images displaying up to four layers. There were significant differences in the size of lesions between different layers of multilayer ring appearance (p < 0.001). All lesions exhibited a two-layer appearance on diffusion-weighted imaging (DWI), with hyperintensity at the periphery and a slightly high signal at the center (except for those with a single layer on T2WI). The "vascular penetration sign" was observed in most lesions, and the blood vessels of 112 lesions (92.56%) were portal vein branches, and five (4.13%) were hepatic vein branches. Pulmonary metastasis was found in three patients with the "vascular penetration sign" of hepatic vein branches.

Conclusion: The multilayer ring appearance on T2WI, the "vascular penetration sign", and the two enhancement patterns may be of great significance in the diagnosis and treatment of HEHE. The "vascular penetration sign" of hepatic vein branches may indicate extrahepatic metastasis.

Keywords: dynamic contrast-enhanced magnetic resonance imaging (MRI); extrahepatic metastasis; hepatic epithelioid hemangioendothelioma (HEHE); hepatic vein branches; liver tumor.

Figure 1

Multilayer ring appearance. The multilayer ring appearance was seen most clearly in T2-weighted imaging (T2WI). The multilayer ring appearance with alternating high and low signal intensity (except for in the single-layer structure). (A1–A3) MR images of lesions with a single layer in patient 1. (B1–B3) MR images of lesions with two layers in patient 1. (C1–C3) MR images of lesions with three layers in patient 5. (D1–D3) MR images of lesions with four layers in patient 4. (A1) T2WI shows a single layer with slightly high signal intensity. (A2) Single-layer ring appearance on the delayed phase with peripheral enhancement and low central signal. (A3) Single-layer ring appearance on the diffusion-weighted imaging (DWI) image shows slightly high signal intensity. (B1) T2WI shows a two-layer ring appearance with slightly high peripheral and high central signal intensity. (B2) Two-layer ring appearance on the delayed phase with peripheral enhancement and low central signal. (B3) Two-layer ring appearance on the DWI image shows high peripheral signal intensity and slightly high central signal intensity. (C1) T2WI shows a three-layer ring appearance with slightly high peripheral signal intensity (the first layer), high central signal intensity (the third layer), and intermediate (the second layer) signal intensity, which demonstrates lower signal intensity comparing with that of the other two layers. (C2) Three-layer ring appearance on the delayed phase with obvious peripheral enhancement (the first layer), low central signal intensity (the third layer), and intermediate (the second layer) slight enhancement, which was not as clear as on T2WI. (C3) Three-layer ring appearance on the DWI image shows peripheral hyperintensity (the first layer) and slightly high signal intensity for the other layers. (D1) T2WI shows a four-layer ring appearance with slightly high peripheral signal intensity (the first layer), high signal intensity in the adjacent second layer, and slightly high signal intensity in the third layer and high central signal intensity (the fourth layer). (D2) Four-layer ring appearance on the delayed phase with obvious peripheral enhancement (the first layer), hypo-enhancement in the second adjacent layer, and hyper-enhancement in the third layer with slight central hypo-enhancement, which was not as clear as those on T2WI. (D3) Four-layer ring appearance on the DWI image shows peripheral hyperintensity (the first layer) and slightly high signal intensity for the other layers.

Figure 2

Comparison of lesion size between different multilayer ring appearances. The lesions were grouped according to the number of layers of the multilayer ring appearance. There were significant differences between groups (p < 0.001). The number of layers increased as the size of the lesion increased.

Figure 3

Vascular penetration sign. (A, B) The vascular penetration sign in transverse and coronal MR images. (C) Vascular penetration sign with the portal and hepatic veins in patient 3. The terminal branches of the portal vein are at the bottom, and the branches of the left hepatic vein are at the top.

Figure 4

Two major enhancement patterns. (A–D) Tumors showed ring-like enhancement with hypervascularity and progressive enhancement (patient 4). The ring-like and local enhancements of the lesion in the early arterial (A) and late arterial (B) phases were higher than those of the liver parenchyma, and the lesion in the portal vein (C) and delayed phase (D) showed progressive enhancement and obvious layer-ring enhancement. (E–H) Tumors showed ring-like enhancement with hypovascularity and progressive enhancement (patient 1). The overall enhancement of the lesion in the early arterial (E), late arterial (F), portal (G), and delayed phases (H) was significantly lower than that of the liver parenchyma. During the dynamic enhancement process, the lesion showed gradual ring enhancement in the periphery, and the central enhancement was not obvious.