Ultrasonographic changes in the liver tumors as indicators of adequate tumor coverage with electric field for effective electrochemotherapy

Aim of the study was to characterize
ultrasonographic (US) findings during and after electrochemotherapy of liver tumours
to determine the actual ablation zone in order to verify the coverage of the
treated tumour with sufficiently strong electric field for effective
electrochemotherapy. US findings from two representative patients that describe
the immediate and delayed tumour changes after electrochemotherapy of
colorectal liver metastases are presented. The US findings were interrelated
with magnetic resonance imaging (MRI). Electrochemotherapy-treated tumours were
exposed to electric pulses based on computational treatment planning. The US
findings indicate the immediate appearance of hyperechogenic microbubbles along
the electrode tracks. Within minutes, the tumours became evenly hyperechogenic,
and simultaneously, an oedematous rim was formed presenting as a hypoechogenic
formation which persisted for several hours after treatment. The US findings overlapped
with the computed electric field distribution in the treated tumours,
indicating adequate coverage of the tumours with the sufficiently strong electric
field, which may predict an effective treatment outcome. US provides a tool for
assessment of appropriate electrode insertion for intraoperative
electrochemotherapy of liver tumours and as indicator of the appropriate
coverage of a tumour with a sufficiently strong electric field and predictor of
the response of tumours.