Radiofrequency Ablation of Hepatic Lesions: A Review

Venkataramu N. Krishnamurthy, MD; V. Javier Casillas, MD; Lina Latorre, MD

Disclosures

Appl Radiol. 2003;32(10) 

In This Article

Abstract and Introduction

For primary and secondary tumors of the liver, surgical resection has been the standard of care. But many hepatic tumors are advanced and are not amenable to surgery. Of the minimally invasive treatments available, radiofrequency (RF) ablation is fast becoming an important alternative treatment modality. In this article, the authors present the technical aspects and outcomes of RF ablation in treatment of hepatic tumors.

The liver is a common site for both primary and secondary malignancies, the most common being hepatocellular carcinoma (HCC) and metastasis from colorectal carcinoma. Hepatocellular carcinoma is the fourth most common cause of cancer-related deaths worldwide, and approximately one million new cases are reported annually.[1] Mortality is essentially 100% when these tumors are not treated. Surgical resection is the standard of care because it has been shown to provide survival benefits, while systemic chemotherapy and radiotherapy are largely ineffective.[2,3] However, only 5% to 15% of patients with HCC or hepatic metastasis are candidates for curative surgery.[2,4,5] The major limiting factors for surgical treatment are too many tumors, large lesions, tumors in unresectable locations, tumors with major vascular invasion, insufficient hepatic reserve from cirrhosis, and underlying medical problems that increase the surgical risk. There is also significant peri-operative morbidity and mortality. The average 5-year survival rate after successful resection for both HCC and metastasis is only 20% to 40%.[4,5] A considerable number of patients will develop recurrence of tumor, which is usually fatal.

Various minimally invasive techniques have been developed as an alternative to surgery. The most important are percutaneous ethanol injection (PEI), hepatic arterial chemoembolization, and thermal ablation techniques. Percutaneous ethanol injection has been reported to be primarily successful in small HCC and is not very useful for treatment of metastatic tumors.[6] Chemoembolization is often reserved for unresectable tumors.[7] Recently, thermal ablation techniques have become popular. There are two types--cold (cryoablation), and heating ablation techniques. The latter includes radiofrequency, microwave, laser, and high-intensity focused ultrasound (US) ablations. Cryoablation is the most popular among surgeons with reported success rates similar to resection surgery.[8] But this technique is invasive, requiring laparotomy in most cases. Experience with microwave and laser ablations is limited and the high-intensity focused US technique is still in the experimental stage.[9,10,11]

Radiofrequency (RF) ablation has gained more popularity in the last decade and is claimed to be a very promising technique for both primary and secondary hepatic tumors.[12,13] Radiofrequency ablation produces controlled coagulation of the tumor by heating the tissue to temperatures above 50°C. Recent studies have reported favorable survival rates and excellent rates of local tumor control by RF ablation, especially in patients with HCC.[12,13,14,15] In this article, we will discuss the historical background, mechanism of RF ablation, optimal ablation technique, imaging follow-up evaluation, procedural complications, and results. Combination therapy of RF ablation with other techniques is also presented.

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