Radiofrequency ablation (RFA) has become
mainstream among non-surgical treatment modalities in clinical
settings for the treatment of hepatocellular carcinoma. We
have previously described the novel combination therapy of
percutaneous ethanol injection and RFA (PEI-RFA) and
reported that this combination therapy was more effective
than RFA alone in terms of the induced volume of coagulated
necrosis and the energy requirement for the treatment. RFA
instruments are mainly divided into two types according to
the electrode used, either the straight or expandable type
electrode. Although PEI-RFA can be performed by either of
the electrodes, there may be some important differences in
PEI-RFA according to the type of electrode used. In the
present study, the effect of using the straight or expandable
electrode in PEI-RFA was evaluated by analyzing the ablation
time, volume of coagulated necrosis, the energy requirement
for ablation and the amount of injected ethanol into HCC.
The comparative study showed that ablation time, total energy
requirement and per unit volume of energy requirement for
whole and marginal coagulated necrosis were significantly
smaller in the group treated with the expandable electrode
(E group) than those in the group treated with the straight
electrode (S group). The volume of coagulated necrosis was
similar between these groups. In group E, the amount of
injected ethanol showed a positive correlation with the volume
of coagulated necrosis and the size of the tumors. These
results suggest that prior injection of ethanol works mainly
by shortening the time and energy requirement for ablation in
the time-lag PEI-RFA using the expandable electrode. Thus,
prior injection of ethanol before RFA may make RFA treatment
less invasive in the time-lag PEI-RFA using the expandable
electrode as previously shown HCC cases treated with straight
electrode.