Quantitative Real-time Ultrasound Elastography (Shear Wave Elastography - SWE™) for Characterisation of Liver Tumors

Shear Wave Elastography (SWE™) is a quantitative elastography method for measuring tissue stiffness. The difference in stiffness between benign and malignant tumors has been demonstrated by other elastography methods (acoustic radiation force impulse imaging, transient elastography and/or magnetic resonance elastography). The investigators hypothesized that benign liver tumors are softer than malignant liver tumors measured by SWE™, allowing differentiation between the two by tumor stiffness expressed in kilopascal (kPa). In this study benign and malignant liver tumors will be evaluated in five groups: 1) hemangioma and 2) focal nodular hyperplasia (FNH) representing the most common benign liver tumors; 3) metastases and 4) cholangiocarcinoma (CCC), both presenting malignant tumors mostly appearing in otherwise healthy liver, and 5) hepatocellular carcinoma (HCC) mostly occurring in cirrhotic liver, which can potentially influence elastographic measurements therefore querying the appropriateness of comparison between tumors in healthy and cirrhotic liver. Enrolled patients will undergo transabdominal ultrasonography and SWE™ examination. The tumor stiffness will be measured five times for each tumor. Additionally, surrounding liver parenchyma stiffness will be measured. The nature of the liver tumor will be defined through a standard diagnostic workup according to current guidelines, including contrast enhanced multi-slice CT, MRI and/or cytology/histology, as applicable. In the final analysis the mean tumor stiffness and tumor-parenchyma ratio will be calculated for each group as well as for benign and malignant tumors separately, and cut-off values for the differentiation of various groups will be derived. The clinical value of the method will be appraised based on specificity, sensitivity, positive and negative predictive values, and AUC.