Usefulness of Radiofrequency Ablation with a Micro-Convex Ultrasound Probe for the Treatment of Hepatocellular Carcinoma

Abstract

Purpose: Radiofrequency ablation (RFA) has been clinically employed in Japan, and its usefulness in the treatment of hepatocellular carcinoma (HCC) has been reported by many researchers. RFA can be performed in various ways: percutaneously, laparoscopically, via a small incision, or intraoperatively. In our department, we generally perform echo-guided percutaneous RFA. The present study was conducted to assess the usefulness of RFA using a micro-convex probe. Methods: The subjects were 27 patients (19 men and 8 women, age range: 37–83 years, average age: 65.9 years) with 29 HCC nodules confirmed by contrast CT or abdominal angiography. In nodule size classification, no nodules were ≤1.0 cm in diameter, 7 were 1.1–2.0 cm, 18 were 2.1–3.0 cm, and 4 were 3.1–5.0 cm. A diagnostic ultrasound system (Aplio, Toshiba, Japan) and a micro-convex probe (PVT382BT, Toshiba) provided with the Aplio were used for treatment. This probe permits puncture angles of 67° and 80° to be set and needles from 13G–22G to be used. A Cool-tip cluster needle was used in 3 patients and a 3.5-cm RTC needle was used in the other 24 patients. In this study, scanning with ApliPure™ (a new function of Aplio) and conventional B-mode scanning were also compared in 5 patients. The therapeutic effect was assessed using contrast CT and contrast echo images. The Advanced Dynamic Flow Imaging technique was employed for contrast echo studies. Results: Puncture was performed successfully for all 29 nodules in all 27 patients for which RFA was performed. The blind area in which the needle is not visible in the image is minimal with the Aplio system. ApliPure™ is a technique combining spatial compounding and frequency compounding, and it is said to improve continuity of the edges of lesions. Although the number of cases in this study was small, we found that clearer images were obtained using this technique. Four nodules that were located 10 cm from the liver surface were not visualized in contrast echo studies performed before and after treatment. For the remaining 25 nodules, however, the therapeutic effect could be assessed. In addition, the micro-convex probe permitted treatment to be performed successfully without artificial pleural effusion for 3 nodules located immediately below the diaphragm that were not visualized using a conventional convex probe. Conclusions: The use of a micro-convex probe helps to ensure more precise and more accurate percutaneous RFA of HCC.