Application of contrast-enhanced ultrasound in differential diagnosis of hypoechoic focal liver lesion in transplanted liver

Objective To evaluate the role of the contrast-enhanced ultrasound(CEUS) in differential diagnosis of hypoechoic focal liver lesions in transplanted liver.Methods The patients with hypoechoic focal liver lesion after liver transplantation were examined by CEUS using Siemens Sequoia 512 and contrast medium Sonovue. The infusion patterns of Sonovue were observed in the three phases and the auto-tracing contrast quantitative technique(Axius ACQ) was used in the hypoechoic focal liver lesions and the surrounding hepatic parenchyma.Results 379 patients underwent liver transplantation in this hospital from January 2005 to July 2006.Hypoechoic focal liver lesions occurred in 10 of 379 patients.Five patients developed infarct lesion;the hypoechoic lesion was anechogenic and confirmed by ACQ.Three patients developed non-uniform fatty liver;the hypoechoic lesion was hyperechogenic comparied with the surrounding hepatic parenchyma in the arterial and portal phases.The analysis of ACQ demonstrated that the hypoechoic lesion was the normal liver tissue,and the blood infusion of the surrounding hepatic parenchyma was insufficient characterized.Two patients redeveloped liver cancer;the hypoechoic lesion was characterized by an intense and fast peak of enhancement in the arterial phase,followed by a quick wash out in the portal and late phases.Conclusions CEUS effectively shows the blood distribution in the liver,and helps differentiate between infarct lesion,non-uniform fatty liver,and liver cancer reoccurrence;it is of great clinical significance.