Use of fusion imaging combining contrast-enhanced ultrasonography with a perflubutane-based contrast agent and contrast-enhanced computed tomography for the evaluation of percutaneous radiofrequency ablation of hypervascular hepatocellular carcinoma

ObjectiveWe evaluated the efficacy of fusion imaging, which fuses contrast-enhanced ultrasonography images with arterial-phase, contrast-enhanced CT images as a reference on a single screen in real time, for the evaluation of the effectiveness of radiofrequency ablation for treatment of hypervascular hepatocellular carcinoma.Materials and methodsEighty hepatocellular carcinoma lesions with a maximum diameter of between 1 and 3 cm that were scheduled for treatment with radiofrequency ablation were enrolled in this prospective study. After bolus injection of perflubutane-based contrast agent, fusion imaging combining contrast-enhanced ultrasonography images and arterial-phase, contrast-enhanced CT images was performed one day after radiofrequency ablation. We used two functions, which were subsets of the fusion imaging, to confirm the location of the hepatocellular carcinoma lesions in the ablated areas and to evaluate the presence or absence of an adequate safety margin. Contrast-enhanced CT was performed one month after the ablation. Two blinded observers reviewed the images obtained using both modalities to evaluate the effect of ablation.ResultsWhen the one-month contrast-enhanced CT images were used as the reference standard, the sensitivity, specificity, and accuracy of the one-day fusion imaging for the diagnosis of adequate ablation were 97%, 83%, and 96%, respectively; the kappa value for the agreement between the findings obtained using the two modalities was 0.75.ConclusionFusion imaging combining contrast-enhanced ultrasonography images and arterial-phase, contrast-enhanced CT images as a reference appears to be a useful method for the early evaluation of the efficacy of radiofrequency ablation for the treatment of hypervascular hepatocellular carcinoma.