Detection of Liver Metastases with Contrast Enhanced Ultrasonography

Detection of liver metastases is one of the most common problems in evaluating patients with primary neoplasms. Gray-scale and color Doppler ultrasonography have limited accuracy with a sensitivity ranging between 53% and 77%. Isoechoic metastases and nodules under 1 cm in size may not be detectable. Occasionally, non-metastatic liver lesions can be identified in neoplastic patients which must be correctly characterized. Microbubble contrast agents overcome many limitations of gray-scale ultrasonography to detect liver metastases and increase the possibility to differentiate them from other focal liver lesions. In this review article we discuss the current role of contrast enhanced ultrasonography in detection of liver metastases using specialized destructive and non-destructive modes. Using air-filled microbubbles and destructive modes the sensitivity of contrast enhanced ultrasonography to detect liver metastases ranges between 80% and 98%. The ease of use of the non-destructive approach makes it much more attractive and is particularly helpful for lesion characterization. An increasing number of studies is being published regarding the diagnostic performance of perfluorocarbon- or sulfur hexafluoride-filled microbubbles with non-destructive modes to detect liver metastases, and the general agreement is that sensitivity and specificity of the non-destructive modes approach those of the destructive approach and of helical CT.