Objective: Sonazoid is contrast agent phagocytosed by Kupffer cells, and so can be used to assess not only blood flow, but also Kupffer imaging, and the contrast effects last for a long period of time at a low acoustic pressure. To assess the usefulness of Sonazoid-enhanced sonographically guided real-time radiofrequency ablation (RFA) for liver tumors that are difficult to treat under conventional ultrasound guidance.
Methods: Sonazoid-enhanced sonographically guided real-time RFA was performed percutaneously for 106 liver tumors (103 hepatocellular carcinomas, 3 liver metastases). TOSHIBA SSA-770A was used. A 0.7ml bolus of Sonazoid was injected intravenously. When contrast effects became weak, an additional 0.3ml was administered.
Results: All liver tumors that could not be clearly visualized on conventional B-mode ultrasonography could be treated easily and successfully by RFA based on the hypoechoic lesions seen with Kupffer imaging in the late phase of Sonazoid-enhanced sonography. The RFA needle could be inserted accurately into post-therapeutic residual tumor, local recurrence or feeding arteries of the tumor by continuously monitoring tumor blood flow and the needle tip using flash replenishment imaging in the early phase. Areas with insufficient margins were easily identified with Kupffer imaging and additional RFA could be precisely performed, as needed.
Conclusion: Sonazoid-enhanced sonography enables real-time RFA while monitoring tumor blood flow and Kupffer images. By facilitating accurate treatment of liver lesions that cannot be clearly identified under conventional ultrasound guidance, this newly introduced method will probably contribute greatly to improvements in the prognosis of liver tumors.