Evaluation of contrast-enhanced ultrasonography for hepatocellular carcinoma prior to and following stereotactic body radiation therapy using the CyberKnife® system: A preliminary report

The CyberKnife® is expected to be a novel local treatment for hepatocellular carcinoma (HCC), however, a long-term follow-up using dynamic computed tomography and magnetic resonance imaging is required to determine the effect of treatment in a number of the affected patients. Therefore, there is a requirement to evaluate procedures for early determination of the effect of CyberKnife treatment. The present study aimed to evaluate the changes in the hemodynamics of the tumors and the hepatic parenchyma surrounding the tumor prior to and following CyberKnife treatment for HCC. A total of 4 HCC patients were enrolled in this study. These patients underwent CyberKnife treatment and were evaluated by image analysis prior to and following treatment using contrast-enhanced ultrasonography (CEUS) with Sonazoid. CEUS was performed prior to treatment, at 2 and 4 weeks post-treatment, and every 4 weeks thereafter for as long as possible. The dynamics of the enhancement of the tumor and the hepatic parenchyma surrounding the tumor in the vascular phase, and the presence or absence of a hypoechoic area in the hepatic parenchyma surrounding the tumor in the post-vascular phase were assessed. Results showed that: i) In the patient with earlier changes, hemodynamic changes were evident in the tumor at 4 weeks and in the hepatic parenchyma surrounding the tumor at 2 weeks post-treatment, respectively; ii) the tumor showed hypoenhancement in all patients; and iii) with regard to findings in the hepatic parenchyma surrounding the tumor, strong hyperenhancement appeared in the vascular phase initially, followed by a hypoechoic area in the post-vascular phase. Evaluation of the hemodynamics of tumors and hepatic parenchyma surrounding the tumor using CEUS with Sonazoid may be therapeutically applicable, as it is less invasive than dynamic computed tomography (CT) and provides an early evaluation of the effectiveness of CyberKnife treatment.