Assessment of ablation zone of liver tumor by 3DUS-US fusion imaging based on electromagnetic positioning: an experimental study

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Objective To investigate the feasibility and accuracy of three-dimensional ultrasound-ultrasound (3DUS-US) fusion imaging based on electromagnetic positioning in the assessment of ablation zone of liver tumor through experimental study in phantom models. Methods Sixteen phantom models which could be ablated and used to assess the ablation zone were established. Then, they were ablated and divided into complete ablation group (n=8) and incomplete ablation group (n=8) randomly. Their ablation effects were assessed by 3DUS-US fusion imaging. If the tumor model was assessed as incomplete ablation, the maximum thickness of the residual tumor was measured. The assessments of gross specimen were used as golden standard to validate the feasibility and accuracy of assessment of 3DUS-US fusion imaging. The success rate of registration, duration time of fusion imaging, accuracy rate of assessment and measurement error in incomplete ablation group were recorded. Results All of the 16 phantom models were produced successfully. The success rate of registration was 100% and the duration time of 3DUS-US fusion imaging was (3.9±1.0)min. The accuracy rate of assessment was 100%. There was no significant difference between the assessment of residual tumor thickness in incomplete ablation group by 3DUS-US fusion imaging and gross specimen (t=-0.814, P=0.442), and the measurement error was (1.1±0.6)mm. Conclusions 3DUS-US fusion imaging based on electromagnetic positioning is a feasible, accurate and convenient method in the assessment of ablation zone of liver tumor. It would be a new immediate precise assessment method during ablation procedure for liver tumor. Key words: Ultrasonography; Ablation techniques; Image fusion; Electromagnetic positioning