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

RF Ablation Procedure

The RF ablation can be performed by three different approaches, including percutaneous, intraoperative, and laparoscopic routes. The percutaneous approach is preferred because it is least invasive, is associated with minimal morbidity, has a lower cost, can be performed on an outpatient basis, and can be repeated as necessary to treat recurrent disease. The intraoperative and laparoscopic approaches are useful in certain special circumstances, which will be discussed separately.

The patient should fast for 6 to 8 hours prior to the procedure. A large peripheral intravenous (IV) access is established, and the patient is monitored to track cardiac and respiratory rate, blood pressure, and peripheral oxygen saturation. Although there is no consensus about routine administration of antibiotics, we administer a single IV dose of ampicillin and cephalosporin, starting 30 minutes to 1 hour prior to the procedure. We continue oral cephalosporin for 5 to 7 days after the procedure.

The procedure can be performed under IV conscious sedation or general anesthesia, depending on the patient and operator preferences. A preanesthetic evaluation should be performed. Fentanyl citrate and midazolam hydrochloride are used for IV conscious sedation. Deeper sedation can be obtained with IV propofol infusion. General anesthesia is highly recommended if the ablation procedure is expected to be extensive and last >=3 hours.

The actual needle insertion can be performed under US or CT guidance, depending on which shows the tumor best and the operator preference (Figure 1). In general, US is the most commonly used modality because it provides good real-time guidance for needle placement, is less expensive, and is quicker to perform.[25,26,27] However, during the ablation process, echogenic bubbles form that can limit visibility, making it difficult to assess the completeness or the extent of the coagulation necrosis. CT is useful in monitoring the ablation process since the perimeter of the ablated area can be better visualized.

(A) Needle localization by ultrasound. The distal electrodes are seen as small bright echoes. (B) Needle localization by CT. The distal metallic electrodes are easily identified.

(A) Needle localization by ultrasound. The distal electrodes are seen as small bright echoes. (B) Needle localization by CT. The distal metallic electrodes are easily identified.

The goal of treatment is to obtain complete tumor destruction. If the RF ablation were to be as successful as surgical resection, the ablation should achieve a reasonably good tumor-free margin (at least 1 cm, preferably 2 cm).[28] Therefore, ablation should extend to a cuff of at least 1 cm of normal hepatic parenchyma. Current RF devices can produce a 3-cm sphere of ablation. Therefore, they are ideal to ablate tumors <1 cm in diameter (subtracting 2 cm from the 3-cm diameter for the 360° 1-cm tumor-free margin).[13] Technical strategy of larger tumor ablation is described below.

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