Percutaneous Ablation for Hepatocellular Carcinoma: Comparison of Various Ablation Techniques and Surgery

Abstract

Image-guided percutaneous ablation is considered best in the treatment of early-stage hepatocellular carcinoma (HCC). Ablation is potentially curative, minimally invasive, and easily repeatable for recurrence. Ethanol injection used to be the standard in ablation. However, radiofrequency ablation has recently been the most prevailing ablation method for HCC. Many investigators have reported that radiofrequency ablation is superior to ethanol injection, from the viewpoints of treatment response, local tumor curativity, and overall survival. New-generation microwave ablation can create a larger ablation volume in a shorter time period. Further comparison studies are, however, mandatory between radiofrequency ablation and microwave ablation, especially in terms of complications and long-term survival. Irreversible electroporation, which is a non-thermal ablation method that delivers short electric pulses to induce cell death due to apoptosis, requires further studies, especially in terms of long-term outcomes. It is considerably difficult to compare outcomes in ablation with those in surgical resection. However, radiofrequency ablation seems to be a satisfactory alternative to resection for HCC 3 cm or smaller in Child-Pugh class A or B cirrhosis. Furthermore, radiofrequency ablation may be a first-line treatment in HCC 2 cm or smaller in Child-Pugh class A or B cirrhosis. Various innovations would further improve outcomes in ablation. Training programs may be effective in providing an excellent opportunity to understand basic concepts and learn cardinal skills for successful ablation. Sophisticated ablation would be more than an adequate alternative of surgery for small- and possibly middle-sized HCC.

Figure 1

We participated in development of a dedicated ultrasonic transducer and have used it in 12,000 procedures of radiofrequency ablation. The dedicated ultrasonic transducer has the following advantages: (1) needle slot is located inside the transducer, (2) a puncture angle of 100 degrees is available in addition to 55, 70, and 85 degrees, (3) the same image is obtained as a regular convex transducer generates, (4) a puncture attachment is unified with the transducer, and (5) it is capable of multimodality fusion imaging.

Figure 2

We developed a dedicated procedure bed. Using this bed, we can keep a patient in an optimal position, such as right hemilateral decubitus position, left hemilateral decubitus position, head-up position, sitting position, and almost standing position.

Figure 3

Lecture topics are current status of ablation, ablation systems, ultrasound systems, various techniques in ablation, and others.

Figure 4

In live demonstrations, we perform ablation on various cases: a case of first diagnosed cancer not difficult to ablate judging from its size and location, a case of a tumor beneath the diaphragm requiring artificial ascites, a case of a tumor in the caudate lobe, a case of a tumor adjacent to the heart, a case of a tumor next to portal vein or hepatic vein at porta hepatis, a case of a tumor over 5 cm in diameter, a case of more than five tumors, cases of hepatic metastasis from the colorectal cancer or the gastric cancer, a case of simple nodular type HCC with extranodular growth or confluent multinodular type HCC, a case of a tumor with unclear boundaries on ultrasound which requires contrast-enhanced ultrasound to perform RFA, a case in which a tumor cannot be detected on ultrasound and requires support of fusion imaging, and others. From these cases, we demonstrate the importance of appropriate patient posture, usefulness of our original dedicated probe for interventional procedures and our RFA dedicated operation table, and the way to carry out ablation under contrast-enhanced ultrasound guidance and with multimodality fusion imaging.

Figure 5

In case studies, difficult to ablate cases from participants' institutions are presented and discussed.