In general, our indications for ablation therapy were as follows: (a) tumor within three or fewer nodules and less than 3 cm in diameter, (b) no radiological evidence of tumor involvement in the major portal and hepatic veins, (c) no evidence of extrahepatic metastases, and (d) Child–Pugh class A or B disease. However, for some patients who did not meet these conditions, we conducted ablation therapy if they were likely to benefit from prolonged survival.
Two hepatologists with 10 and 5 years of experience conducted RFA and MWA procedures via real-time ultrasound (Aplio500, Canon Medical Systems, Ohtawara, Japan) using a convex transducer ultrasound probe. We intravenously injected 15 mg of pentazocine and 3 mg of midazolam before the procedure. When patients were inadequately sedated, we infused midazolam with careful observation until appropriate sedation was obtained. We also intravenously administered 15 mg pentazocine when patients seemed to experience pain during the procedure. We performed artificial pleural effusion and/or the artificial ascites technique in patients with tumors below the hepatic dome and adjacent to other organs, including the gastrointestinal tract. In general, we used a fusion imaging technique to identify the precise tumor location. We also used contrast-enhanced ultrasonography (CEUS) when the tumors were not clearly visible, despite fusion imaging. For the MWA, we used a 13-gauge, internally saline-cooled coaxial antenna (EmprintTM System; Covidien, Boulder, CO, USA). The antenna was inserted into a targeted tumor, and the output energy was applied. We started at 45 W for 1 min and then gradually increased to 60 W for 1 min, 75 W for 1 min, and 100 W for 3.5–8.5 min to obtain optimal necrosis. For RFA, we used a 17-gauge internally cooled length-adjustable electrode (VIVA RF System; STARmed, Gyeonggi-do, Goyang-si, Republic of Korea). The active length of the tip was determined based on the size of the target tumor. The electrode was inserted into the targeted tumor, and radiofrequency energy was delivered. We started with 40 W for the 2 cm exposed tip and 60 W for the 3 cm exposed tip, and the output energy was gradually increased at a rate of 20 W per minute.
We performed enhanced dynamic CT the day after ablation therapy. When a residual portion of the targeted tumor was suspected, we performed additional ablation therapy.
Two hepatologists with 10 and 5 years of experience conducted RFA and MWA procedures via real-time ultrasound (Aplio500, Canon Medical Systems, Ohtawara, Japan) using a convex transducer ultrasound probe. We intravenously injected 15 mg of pentazocine and 3 mg of midazolam before the procedure. When patients were inadequately sedated, we infused midazolam with careful observation until appropriate sedation was obtained. We also intravenously administered 15 mg pentazocine when patients seemed to experience pain during the procedure. We performed artificial pleural effusion and/or the artificial ascites technique in patients with tumors below the hepatic dome and adjacent to other organs, including the gastrointestinal tract. In general, we used a fusion imaging technique to identify the precise tumor location. We also used contrast-enhanced ultrasonography (CEUS) when the tumors were not clearly visible, despite fusion imaging. For the MWA, we used a 13-gauge, internally saline-cooled coaxial antenna (EmprintTM System; Covidien, Boulder, CO, USA). The antenna was inserted into a targeted tumor, and the output energy was applied. We started at 45 W for 1 min and then gradually increased to 60 W for 1 min, 75 W for 1 min, and 100 W for 3.5–8.5 min to obtain optimal necrosis. For RFA, we used a 17-gauge internally cooled length-adjustable electrode (VIVA RF System; STARmed, Gyeonggi-do, Goyang-si, Republic of Korea). The active length of the tip was determined based on the size of the target tumor. The electrode was inserted into the targeted tumor, and radiofrequency energy was delivered. We started with 40 W for the 2 cm exposed tip and 60 W for the 3 cm exposed tip, and the output energy was gradually increased at a rate of 20 W per minute.
We performed enhanced dynamic CT the day after ablation therapy. When a residual portion of the targeted tumor was suspected, we performed additional ablation therapy.
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