Contrast-Enhanced Ultrasonography for Characterization of Liver Lesions in Dogs and Cats

Abstract

Liver nodules are common in dogs. Contrast-enhanced ultrasound (CEUS) is commonly used to characterize focal hepatic lesions in humans. Three vascular phases have been described in the liver: arterial phase, portal phase, and late phase. Contrast-ultrasonographic features of canine liver lesions have also been described. The hypoechogenicity at peak liver enhancement and during the portal phase has been significantly associated with malignancy with high sensitivity and specificity. Few reports on contrast ultrasonographic features of hepatic lesions in cats are available. The aim of this study was to describe contrast ultrasonographic features of 16 liver lesions in 13 dogs and two cats. All patients underwent fundamental abdominal ultrasound, anesthesia, contrast-enhanced ultrasound with a second-generation contrast medium (sulfur hexafluoride-SonoVue^®), fine-needle aspiration/tissue core or surgical biopsy of the lesions, followed by cytological/histological examination. Ten lesions were benign (four nodular hyperplasias, three simple cysts, two nodules of focal hydropic degeneration, and one eosinophilic infiltration) and six were malignant (four hepatocellular carcinomas, one biliary carcinoma, and one lymphoma). All benign lesions, with the exception of the simple cysts, were iso- or hyperechoic to the surrounding tissue in the portal phase, while all malignant lesions were hypoechoic. The hypoechogenicity during the portal phase was significantly associated with malignancy with high sensitivity and specificity (100% and 70%, respectively). According to the literature, CEUS of the liver resulted in a safe diagnostic procedure that was of value in differentiating benign from malignant hepatic lesions. CEUS, however, is not able to define tumor cell type, and either biopsy or fine-needle aspiration is recommended to achieve a final diagnosis.