9 - Radiofrequency equipment and scientific basis for radiofrequency ablation

Summary

Introduction

Minimally invasive strategies for tumor ablation, such as radiofrequency (RF) thermal ablation, have now gained prominent attention for the focal destruction of hepatic malignancies and are considered mainline therapies for some focal malignancies. Advantages of minimally invasive therapies compared to surgical resection include the anticipated reduction in morbidity and mortality, lower cost, the ability to perform procedures on outpatients, and the potential application in a wider spectrum of patients, including non-surgical candidates.

Thermal ablation strategies utilize alterations in tissue temperature to induce cellular disruption and tissue coagulation necrosis. This chapter will provide a conceptual framework for the principles and theories that underlie focal thermal tumor therapy using radiofrequency ablation (RFA). Particular emphasis will be placed on design and current use of radiofrequency equipment. Furthermore, developing synergistic therapies that allow treatment design tailored to patient specific disease will be discussed, as it is anticipated that these will further increase long-term success rates.

Basic principles of radiofrequency ablation

Goals of minimally invasive tumor ablation

The ultimate strategy of RF thermal tumor ablation therapy for hepatic and other malignancies encompasses two specific objectives. First, through the application of energy, to attempt to completely eradicate all viable malignant cells within a designated area. Based upon studies examining tumor progression for patients undergoing surgical resection, and the demonstration of viable malignant cells beyond visible tumor boundaries, tumor ablation therapies attempt to include at least a 1.0 cm “ablative” margin of seemingly normal tissue for liver, but less may be needed for some tumors such as kidney.