Value of wash-in and wash-out time in the diagnosis between hepatocellular carcinoma and other hepatic nodules with similar vascular pattern on contrast-enhanced ultrasound

Background and AimThe study aims to demonstrate whether the wash-in and wash-out time can be reliable as a criterion in the differential diagnosis between hepatocellular carcinoma (HCC) and other hepatic nodules with vascular pattern similar to HCC on contrast-enhanced ultrasound (CEUS). MethodsFrom February 2012 to February 2013, 214 patients with hepatic nodules displayed rapid hyperenhancement and quick wash-out on CEUS were included in this study. Before performing CEUS, all nodules were examined by grayscale ultrasonography and color Doppler techniques. CEUS was performed with SonoVue and low mechanical index technique. The initial time to enhancement, time to peak, time of the nodule being hypoenhanced were comparatively studied between HCCs and other hepatic nodules. ResultsOf all the 214 nodules, 209 were malignant (164 HCCs, 31 metastases, 10 intrahepatic cholangiocarcinomas (ICCs), 3 combined hepatocellular-cholangiocarcinomas, 1 epithelioid hemangioendothelioma), and five were benign (two inflammatory pseudotumors, one focal nodular hyperplasia nodule, one hemangioma, and one hyperplastic nodule). Metastases and ICCs showed more rapid wash-out than HCCs (P<0.05): 16 of 31 metastases and 7 of all ICCs showed wash-out by 40s after injection. ConclusionsSome focal liver lesions can show enhancement pattern similar to HCCs on CEUS. The wash-out time may be useful in the differential diagnosis.