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material and methods

    • RFA of unresectable primary and metastatic liver tumors was applied to treat 224 tumors in 170 patients.  All patients had tumors proven at pathologic histology:
      • Hepatocellular carcinoma: n=86
      • Metastases: n=83
      • Colorectal (n=69), breast (n=12)
      • Stromal tumor (n=1), melanoma (n=1)
      • Cholangiocarcinoma: n=1
    • Number of tumors was ranged from 1 to 5 in a same patient.
    • The greatest diameter of the tumor measured 9 cm (range 1-9 cm).
    • All patients with liver metastases were treated by systemic chemotherapy before RFA


    • RF Generator  (375 kHz): ELEKTROTOM HiTT  (Berchtold, Tuttlingen, Germany
      • Needle Electrodes
      • Diameter/Shaft Length/active zone: 14 g/ 150-200/ 15-20 mm. The holes in the distal part of the electrode (active zone) serve for saline infusion through the needle, into the surrounding tissue.
      • Power applied: 40-50 W. Perfusion of sterile saline solution was achieved by using a pump
        •      0.9 % NaCl: rate of 105 ml/h
        •      5 % NaCl: rate of 70 ml/h
      • When the impedance increased the perfusion rate increased (bolus) automatically for 1.2 seconds with simultaneous power decrease to 5 Watts (Computer controlled generator). The emerging low flow of the perfusion solution is heated together with the tumor environment to boiling point (the calculated inflow and partial evaporation of saline solution physically prevent any overheating of the needle electrode above the limit of 100 °C). Two dispersive grounding pads were placed on the abdominal wall of the patients. Mean energy dose applied for 5 minutes was 14500 Joules
      • RF ablation time was 10-25 minutes for each tumor


    Treatment response, complications and diagnosis of new liver and/or distant metastases were evaluated with helical CT and/or MRI after 24 hours, 1 month and every 3-4 months. Patients were followed-up 6 to 24 months (mean 11 months)


    • RFA was performed percutaneously (166 patients) and intra-operatively (4 patients).
    • Antibiotic prophylaxis was no systematic.
    • Percutaneous RFA was performed with conscious sedation.
    • Repeat treatment was performed when partial necrosis was obtained or when local recurrence or new metastases were observed. Multiple lesions were often treated in a single session.

Berchtold Radiofrequency Ablation System

surface area of the electrode ’s active tip (with  holes for saline infusion)

CT guidance