Some percutaneous treatment modalities such as radiofrequency ablation (RFA) are used for the treatment of liver tumors; however, they do not achieve complete tumor ablation. Conventional ultrasonography during RFA permits neither clear tumor visualization nor tumor sampling. We developed a rotational scraper, which facilitates safe tumor enucleation under ultrasonic guidance.
Method: Four post-mortem porcine livers were examined. The delivery tube comprised an outer sheath, which formed the aspiration channel, enclosing an inner sheath defining the irrigation channel. The distal end of the inner cannula was equipped with manually controllable blades. Ultrasonic vibrators were attached to the blades. A gear for rotation and electrodes for ultrasonography were attached to the proximal end of the inner tube, and a motor for the rotation of the scraper was installed. The roughly estimated target for RFA was approached via the delivery tube under ultrasonographic guidance. Using endoscopic ultrasonography, the tumor site and adjacent tissue were examined for blood vessels or bile duct to prevent damage to these structures. The blade height was gradually increased using the proximally placed handles, with simultaneous irrigation and aspiration. Complete tumor enucleation was confirmed by ultrasonography.
Result: 1. Tissue aspirate for pathological assessment was obtained. 2. Low ultrasonic frequency facilitates observation of tumors >2 cm. 3. Aspiration channel should be large for efficient aspiration. 4. Tissue fragments impede endoscopic ultrasonography.
Conclusion: Further investigations are required to identify the optimal frequency for clear tumor visualization and to develop methods with reduced risk of bleeding and tumor seeding in vivo.