Tumor-Specific Vascularization Pattern of Liver Metastasis, Hepatocellular Carcinoma, Hemangioma and Focal Nodular Hyperplasia in the Differential Diagnosis of 1349 Liver Lesions in Contrast-Enhanced Ultrasound (CEUS)

Aim: To evaluate the incidence and diagnostic accuracy of tumor-specific vascularization pattern in contrast-enhanced ultrasound (CEUS) in the differential diagnosis of liver tumors in clinical practice. Materials and Methods: From May 2004 to December 2006 1349 patients (male 677, female 672) with a hepatic tumor lacking a definite diagnosis based on B-mode ultrasound and power Doppler ultrasound were examined at 14 hospitals by CEUS using a standardized protocol (pulse/phase inversion imaging, mechanical index < 0.4). Vascularity pattern and contrast enhancement pattern were analyzed in focal lesions during the arterial, portal, and late phase. The tumor-specific diagnosis established after CEUS was compared to histology (> 75% cases) or in some cases to CT or MRI. Results: The final diagnosis of 573 benign hepatic tumors included hemangiomas (n = 242) and focal nodular hyperplasia (n = 170), other benign lesions (n = 161). Tumor-specific vascularization pattern such as a wheel-spoke pattern and arterial hyperenhancement followed by isoenhancement in the late phase in FNH or a nodular peripheral enhancement and partial or complete fill-in pattern in hemangiomas could be assessed in the majority, but not all lesions. The diagnostic accuracy of CEUS was 83.1% for all benign lesions and 82.2% for hemangioma and 87.1% for FNH. The final diagnosis of 755 malignant hepatic tumors included metastases n = 383, hepatocellular carcinoma n = 279 and other malignant lesions n = 93. Late phase hypoenhancement was seen in almost all liver metastases (94.7%) The diagnostic accuracy of CEUS was 95.8% for all malignant lesions and 91.4% for liver metastases and 84.9% for hepatocellular carcinomas. Conclusion: Tumor-specific vascularization pattern in CEUS have a high diagnostic impact on the overall high diagnostic accuracy of CEUS for the differential diagnosis of hepatic tumors in clinical practice.