Radio-frequency ablation (RFA) to treat lung tumours

In 1995, at Harvard University in America, radio-frequency ablation (RFA) was used for the first time in patients with inoperable lung tumours. Over recent years, a large number of studies have scientifically confirmed the safety and efficiency of this technique, establishing RFA today as an alternative therapy for the treatment of primary and secondary lung tumours not amenable to resection.

The tumour cells are killed by heating them.

Minimally-invasive RFA is intended to replace surgery, chemotherapy or radiotherapy when the risk of accompanying conditions or limited lung function is too great.

RFA is suitable for patients who:

  • have tumours that are no more than 3 cm in diameter (in individual cases up to 5 cm maximum)
  • have tumours that are not near the entrance of the blood vessels to the lungs (hilum)
  • have tumours that are not directly adjacent to major blood vessels (due to the transport of heat, the required temperature cannot be maintained)
  • have tumours that are not near structures that are sensitive to heat (e.g. bronchi and trachea).

Beforehand

A precise determination of the indication and careful preparation are needed for RFA.

In preparation for the procedure, we evaluate the case history and any diagnostic results already available, such as CT images, MRI scans and, if available, PET-CT scans (positron emission computed tomography). To this end, we request that a detailed medical history is provided, with a list of the treatments already applied, an indication of the progression of the disease, and the most up-to-date diagnostic images available.

Based on the documents supplied, we can check whether the most important requirements for RFA are fulfilled. If this is the case, the patient will be invited for a further consultation and work-up at our outpatient clinic for minimally invasive tumour therapy.

During

The procedure is generally very well tolerated under local anaesthetic and a strong pain killer so that in most cases a general anaesthetic is not needed.

During RFA, an approximately 3 mm thick needle electrode is inserted through the skin under CT guidance into the inside of the tumour. Activating the needle electrode cases the tumour area inside the target organ to heat up (to around 100°C). This kills the tumour (coagulation necrosis) (Figure 1). The ablation procedure takes around 15 to 30 minutes.

After this, the needle electrode is removed and the incision channel is sealed with special tissue glue.

Figure 1: Principle of radio-frequency ablation (RFA): By introducing high-frequency alternating current (400 – 500 kHz), the charged particles close to the applicator inserted into the tumour start to move very rapidly. This movement generates heat in the surrounding tissue and therefore leads to cell destruction.

After

Generally speaking, a single RFA treatment is sufficient for small tumours. Larger tumours (> 5 cm) are not treated with RFA at our facility. Instead we use brachytherapy for this situation. If the development of new lung tumours is picked up at later follow-up, the procedure can be carried out again if necessary.

The treatment-related complication rate for RFA is very low.

Potential complications arise in the context of the percutaneous positioning of the RFA probe.

The most common complication is the introduction of air into the pleural fissure with subsequent pneumothorax. This pneumothorax, however, can be treated with a drain inserted percutaneously and by aspirating the air (Bülau drain). The drain remains in situ for a few days and can then be removed.

This lung puncture can also result in the patient coughing up blood (haemoptysis) for a short while. Generally speaking, the CT-guided probe positioning and CT monitoring during the ablation avoids surrounding structures such as the bronchi, trachea, heart, liver, diaphragm, nerves or oesophagus being injured or damaged by the heat.

Infections with abscesses or bleeding can also occur.

Figure 2: The example illustrates the treatment of an isolated lung metastasis with RFA. The CT scan (left image) taken before the treatment shows a single lung metastasis (arrow). For the treatment, the RFA probe is advanced under CT fluoroscopy guidance into the metastasis (middle image). Once the probe is correctly positioned, the metastasis is ablated. Two years after RFA treatment, the CT scan (right image) shows scar changes of the lung tissue at the ablation site.

Contact


Minimally Invasive Tumour Therapy (MITT)
Charité Campus Virchow-Klinikum (CVK)
Department of Radiology
Augustenburger Platz 1
13353 Berlin

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