[Ultrasound diagnosis of liver metastases with liver-specific contrast media]

In recent years sonographic contrast agents which can be used for liver imaging have become available. Some of these agents (e.g. Levovist, Schering AG, Berlin) display a liver-specific late phase. Visualisation of this late phase requires contrast-specific imaging techniques such as phase or pulse inversion. When scanned in phase inversion during the late phase, normal liver parenchyma shows strong enhancement. This enhancement spares metastases which stand out as echo-poor or almost echo-free enhancement defects. This improves the conpicuity of metastases markedly. The technique increases the number of detectable metastases in up 45% of patients in comparison to unenhanced sonography. In a multi-centre study on 128 patients the sensitivity in the detection of individual metastases was increased from 71% to 88% and specificity improved from 59% to 88%. Contrast-enhanced sonography thus represents a promising alternative to other cross-sectional imaging modalities in the diagnosis of hepatic metastases.