1089: Treatment response and treatment guidance of hepatocellular carcinoma: Value of contrast-enhanced harmonic US and RVS

Abstract

Introduction: In 1999, an ultrasound contrast agent was introduced in Japan to the clinical practice of hepatology, especially to the diagnosis and treatment of hepatocellular carcinoma (HCC). Drastic change in the strategies both in the diagnosis and treatment of HCC has been achieved both by contrast agent and the associated innovation of ultrasound technologies. In this lecture, the present status of the new strategy brought by advances of US technologies in the diagnosis, evaluation of treatment response and treatment guidance will be presented. Role of harmonic imaging in the differential diagnosis of hepatic tumors. On contrast harmonic US, typical hemodynamic pattern of HCC, is demonstrated as abundant tumor vessels supplying from the periphery to the center of the tumor and dense tumor parenchymal stain with fast washout in high sensitivity and specificity. Characteristic hemodynamic pattern of metastases is peripheral tumor vessels with rim parenchymal stain in the vascular phase followed by perfusion defect in postvascular phase. Hemangiomas show hypovascular in the early arterial phase with gradual spotty or cotton-wool pooling lasting up to late vascular phase, which is only detected by the long interval-delay scanning. Dysplastic nodules are demonstrated as no early arterial supply with isovascularity in late vascular phase. Focal nodular hyperplasias are demonstrated as spoke-wheel pattern of blood vessels accompanied by dense stain at interval-delay scanning. Pure Arterial Phase Imaging. In 2005, a breakthrough technology, pure arterial phase imaging, which can depict only arterial accumulated MIP images, was developed by the advancement of raw data store technique and accumulation technique. By using these techniques, whether blood supply in the tumor is arterial or portal origin can be clearly depicted, which is not possible by CT or MRI. This is an innovative technique to differentiate premalignant lesion from overt HCC. Application of harmonic imaging to the treatment of HCC evaluation of treatment responses. Harmonic US is extremely useful in the evaluation of posttreatment response of HCC after Lipiodol TAE. Harmonic US can extract only the blood flow echoes created by destruction of microbubbles, whilst echoes from tissue are effectively cancelled. This mode makes it possible to clearly depict residual blood flow in tumors after RFA or PEI therapy. Real-time needle insertion guidance for local treatment of HCC. The capability of harmonic US for depicting residual cancer cells in HCCs after treatment facilitates a correct guidance for the insertion of a needle on US monitoring, which cannot be achieved by any other imaging modalities including CT or MRI. Real-time virtual sonography. Recently, concurrent real-time imaging of MDCT and US is easily obtained, which is called as real-time virtual sonography. This technique extremely facilitates the treatment guidance for HCC. Conclusion. The newly introduced sonographic technique is drastically changing the diagnostic and therapeutic strategy of HCC, resulting in an eventual improvement in the prognosis of HCC patients.