Contrast-Enhanced Ultrasound Phenotypes in Hepatic Alveolar Echinococcosis: Pathological Correlations and Prediction of Vascular Invasion

RATIONALE AND OBJECTIVES: To characterize perfusion phenotypes of hepatic alveolar echinococcosis (HAE) on contrast-enhanced ultrasound (CEUS) and analyze their links to pathology and aggressive biological behavior. MATERIALS AND METHODS: One hundred thirty-nine patients (mean age, 40.9 ± 15.1 years; 65 men) with pathologically confirmed HAE comprising 183 lesions were evaluated. Lesions were classified into 7 CEUS patterns (E1-E7) based on peripheral and internal enhancement features. Comparisons were performed across Ulm subtypes regarding CEUS distribution, quantitative parameters and microvessel density (MVD) in peripheral zones. Vascular invasion was analyzed according to CEUS patterns, and multivariate analyses were conducted to identify predictors of extrahepatic metastasis. RESULTS: Peripheral enhancement occurred in 165/183 lesions (90.2%), internal enhancement in 43 (23.5%). E1 (complete peripheral enhancement without internal enhancement) was most frequent (55.7%). Positive peripheral enhancement was linked to higher portal vein (26.1%) and hepatic vein (21.2%) invasion versus none in negative cases. E2 (discontinuous peripheral ring without internal enhancement) and E4 (discontinuous peripheral ring with internal branching perfusion) were most strongly associated with vascular invasion. Hemangioma-like and hailstorm types had significantly greater perfusion and MVD than pseudocystic types (P < 0.05). Whereas CEUS pattern alone was not directly associated with extrahepatic metastasis, vascular invasion-including inflow (portal vein or hepatic artery) and outflow (hepatic vein or inferior vena cava)-emerged as independent predictors: inflow-vascular invasion increased the odds of extrahepatic metastasis (OR = 9.567, P < 0.01), as did outflow-vascular invasion (OR = 5.855, P = 0.01). A multivariate logistic regression model incorporating these predictors achieved an area under the receiver operating characteristic curve of 0.881 (95% CI: 0.799-0.963), indicating good discriminative performance. This suggests that CEUS perfusion phenotypes may influence metastatic risk indirectly through vascular involvement. CONCLUSION: Peripheral CEUS enhancement, particularly E2 and E4, indicates high vascular invasion risk in HAE. CEUS provides a combined morphological and perfusion assessment to guide surgical planning.