Comparison between baseline and contrast-enhanced ultrasound in characterization of small focal liver lesions

Objective To assess the diagnostic performance of real-time contrast-enhanced ultrasound in characterization of small focal liver lesions in comparison with baseline ultrasound.Methods Two hundred small focal liver lesions (≤ 3.0 cm in diameter) in 200 patients were examined by real-time contrast-enhanced ultrasound mode of contrast pulse sequencing with a sulphur hexafluoride-filled microbubble contrast agent.Two independent investigators reviewed the images before and after contrast agent administration.The diagnostic performances were evaluated using receiver operating characteristic (ROC) analysis and the interobserver agreement was analyzed.Results After review of contrast-enhanced ultrasound,ROC analysis revealed significant improvement in differentiating between malignant and benign small focal liver lesions that the areas under the ROC curve were 0.856 and 0.857 at baseline ultrasound versus 0.954 and 0.943 at contrast-enhanced ultrasound (P 0.001 and P= 0.003 ).The sensitivity,negative predictive value and accuracy for both investigators also improved significantly after reviewing contrast-enhanced ultrasound (all P 0.001 ).A better interobserver agreement was achieved after reviewing of contrast-enhanced ultrasound (κ= 0.425 at baseline ultrasound versus κ= 0.716 at contrast-enhanced ultrasound) and a better result of specific diagnosis was obtained 38.5% (77200) and 34.5% (69200) at baseline ultrasound versus 80.5% (161200) and 80.5% (161200) at contrast-enhanced ultrasound (all P 0.001 ).Conclusions Real-time contrast-enhanced ultrasound improves the diagnostic performance in small focal liver lesions for discrimination between malignancy and benignity and improves the capability in specific diagnosis compared with baseline ultrasound.