Minimally Invasive Tumor Therapy (MITT)

Department of Radiology, Charité – Universitätsmedizin Berlin

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References

  1. S3-Leitlinie Hepatozellulläres Karzinom. http://www.krebsgesellschaft.de/download/s3-hcc-ol-langversion_v1.0_2013.pdf
  2. Forner A, Llovet JM, Bruix J. Hepatocellular carcinoma. Lancet. 2012;379(9822):1245-55
  3. Gervais DA, Goldberg SN, Brown DB, Soulen MC, Millward SF, Rajan DK. Society of Interventional Radiology position statement on percutaneous radiofrequency ablation for the treatment of liver tumors. J Vasc Interv Radiol. 2009;20(1):3-8
  4. Goldberg SN, Charboneau JW, Dodd GD, 3rd, Dupuy DE, Gervais DA, Gillams AR, et al. Image-guided tumor ablation: proposal for standardization of terms and reporting criteria. Radiology. 2003;228(2):335-45
  5. Goldberg SN, Grassi CJ, Cardella JF, Charboneau JW, Dodd GD, 3rd, Dupuy DE, et al. Image-guided tumor ablation: standardization of terminology and reporting criteria. J Vasc Interv Radiol. 2009;20(7 Suppl):S377-90

Radiofrequeny Ablation (RFA) for the Treatment of Liver Tumors

 

Many patients with primary liver cancer (hepatocellular carcinoma (HCC) or cholangiocellular carcinoma (CCC)) or secondary liver tumors (liver metastases) are not candidates for surgery at the time of diagnosis. Surgery is not possible if there are too many tumors or if they are located in a site where surgical removal would be too risky. For others, surgery is not an option because of other health concerns. Finally, patients may develop new liver tumors (intrahepatic recurrence) after initial successful surgical removal. These patients may be candidates for various alternative therapeutic options that have been developed over the last two decades. The aim of these alternative treatments is to selectively destroy liver tumors while preserving healthy liver tissue. Radiofrequency ablation (RFA) is a widely used local treatment for primary and secondary liver tumors. It is one of the most intensely investigated minimally invasive procedures, and many scientific studies have shown that RFA treatment is safe and effective.

 

Therefore, RFA is currently regarded as the best treatment choice for patients whose liver tumors cannot be removed by surgery.

 

How Does RFA Work?

 

RFA uses heat to destroy cancer cells (thermal ablation). The heat is generated within the tumor using a needle-like electrode (RFA probe) with a diameter of about 3 mm. The probe is advanced through the skin (percutaneously) into the tumor using imaging for guidance. This allows the radiologist to see the RFA electrode inside the patient’s body (Figure 1).

 

Figure 1: Mechanism of radiofrequency ablation (RFA). A thin needle-like electrode (RFA probe) placed within the tumor (red) is used to deliver an alternating electrical current. This radiofrequency energy causes agitation of charged particles (ions), generating frictional heat around the electrode tip. In this way, the tissue near the electrode tip can be heated to a temperature of up to 100°C, which results in immediate cell death.

 

 

The techniques for image guidance include ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI). Once the electrode has been positioned, the generator is activated to produce the radiofrequency energy necessary to destroy the tumor. The tumor tissue around the electrode tip is heated to a temperature of up to 100°C, which causes the cells to die (a process known as coagulation necrosis). Radiofrequency energy is applied for 15 – 30 minutes. After ablation of the tumor, the electrode is removed and the tract is cauterized. RFA treatment is minimally invasive because it requires no large skin incisions (cuts). Most patients tolerate the procedure very well with local anesthesia and a strong intravenous painkiller. General anesthesia is usually not required. Many small liver tumors can be treated in a single session. We do not use RFA to treat tumors more than 4 cm in size. For larger tumors, other minimally invasive techniques like high-dose rate brachytherapy appear to be more effective. RFA can be repeated several times if the tumor comes back or if new tumors develop in the liver.

 

What are Possible Complications of RFA?

 

RFA has few complications. Some possible complications are related to the insertion and positioning of the RFA electrode. The risk of injury to nearby organs and of bleeding is lowered by using CT to guide the procedure. There is a very small risk that the heat may damage surrounding organs like the skin, kidneys, bowel, stomach, or lungs.

 

Advantages and Disadvantages of RFA

 

RFA is a safe and effective treatment option with a low complication rate for patients with primary or secondary liver tumors. Several international studies have shown that, in selected patient groups, RFA treatment achieves local tumor control rates that are similar to those of surgical removal. RFA is well tolerated as it requires no large skin incision, and the use of image guidance for insertion and positioning of the RFA electrodes within the tumor minimizes complications. Therefore, it is a good option for patients who had abdominal surgery before or who cannot have surgery for other reasons.

 

Nevertheless, there are liver tumors for which RFA is not advisable. With the currently available RFA probes, we can ablate liver tumors that are up to 4 - 5 cm in size. Another limitation is that RFA becomes less effective when a tumor has high blood flow or is located close to a large blood vessel. In these cases, the blood carries away the heat too fast, and the treatment temperature may be too low to effectively destroy the tumor cells. Therefore, RFA is often not effective enough to ablate liver tumors with high blood flow or liver tumors near a large blood vessel. When a liver tumor is close to heat-sensitive organs (e.g., bile ducts or bowel loops), the risk of damaging these organs by the heat necessary to kill the tumor cells may be too high.

 

For these reasons, RFA is not used to treat liver tumors larger than 5 cm or liver tumors close to heat-sensitive structures like the large bile ducts.

 

Aftercare

 

A patient scheduled for RFA treatment of a liver tumor will be admitted to our ward for about 3- 4 days. There are no restrictions on daily activities after the procedure. You should have a follow-up magnetic resonance imaging (MRI) examination of the liver as an outpatient 6 – 8 weeks after treatment and then every 3 months. Ideally, the MRI examinations should be performed with a liver-specific contrast agent. Follow-up MRI is performed to assess the success of RFA and to rule out new liver tumors. You can have follow-up MRI as an outpatient in our department or elsewhere. If the MRI is done at another site, we kindly ask you to send us a CD with the images for quality control.

 

For further information on RFA of liver tumors, please do not hesitate to contact us. We will be happy to answer any questions you may have.

 

  • Contact:

Minimally Invasive Tumor Therapy (MITT)

Charité, Campus Virchow-Klinikum

Department of Radiology

Augustenburger Platz 1

13353 Berlin, Germany

Phone: +49 (0)30/450-557309

Fax: +49 (0)30/450-557947

minimal-invasive-ambulanz@charite.de oder mia@charite.de

 

Case Example

 

 

Figure 2: This case illustrates the use of RFA for the treatment of a small liver cancer (HCC) in a patient with severe liver cirrhosis.

 

  1. The contrast-enhanced CT scan obtained before treatment shows a bright tumor (arrow) near the liver capsule (subcapsular).
  2. Treatment begins with the placement of the RFA electrode using CT fluoroscopy for guidance. This allows the radiologist to watch the electrode while it is advanced into the tumor. Once the electrode has been positioned properly, the radiologist starts to apply radiofrequency energy for ablation of the tumor.
  3. Another contrast-enhanced CT scan is obtained after RFA treatment and removal of the electrode. As a sign of successful ablation, the tumor no longer takes up contrast medium and appears darker (arrow) than before treatment.