Depiction of portal supply in early hepatocellular carcinoma and dysplastic nodule: value of pure arterial ultrasound imaging in hepatocellular carcinoma

Ultrasound (US) contrast agents such as SonoVue and Sonazoid are commercially available worldwide. Innovation of contrast agents and advances of new US technologies have dramatically changed both diagnostic and treatment strategies for hepatocellular carcinoma (HCC). Recently, the breakthrough technique, pure arterial phase (PAP) US imaging, which depicts only intranodular arterial supply by use of maximum intensity projection (MIP) images, was developed from advanced raw data-storing and accumulation technologies. A total of 8 dysplastic nodules (DNs), 16 early HCCs, 5 nodule-in-nodule type early HCCs and 48 overt HCCs were included in this study. All 8 DNs (100%) showed arterial hypovascularity in the PAP followed by preserved portal perfusion at the portal phase and isouptake at the Kupffer phase by Sonazoid-enhanced contrast US. A total of 12 out of 16 early HCCs (75%) showed similar patterns on vascular and Kupffer phase imaging of contrast-enhanced ultrasonography. The remaining 4 HCCs showed slightly hypervascular pattern without venous washout and slightly decreased Kupffer uptake. All 5 nodule-in-nodule type early HCCs presented partial arterial enhancement within hypovascular nodule at the PAP followed by isovascular pattern at the portal phase and partial Kupffer defect within isouptake nodules. All 48 overt HCCs showed a hypervascular pattern with Kupffer defect on contrast-enhanced ultrasonography. This technique can clearly identify whether blood supply in the tumor is of arterial or portal origin, and facilitate the noninvasive characterization of nodular lesions associated with liver cirrhosis. In conclusion, this newly developed innovative technique can depict pure portal supply in early HCC and DN, enabling differentiating premalignant lesions and early HCCs from overt HCC even though dynamic CT or MRI does not have such capabilities.