  Currently, lung cancer is a leading cause of global cancer mortality, often
necessitating minimally invasive interventions. Microwave ablation (MWA) is
extensively utilized for both primary and secondary lung tumors. Although
numerous clinical guidelines and standards for MWA have been established, the
clinical evaluation of ablation surgery remains challenging and requires
long-term patient follow-up for confirmation. In this paper, we propose a
method termed respiratory subtraction to evaluate lung tumor ablation therapy
performance based on pre- and post-operative image guidance. Initially,
preoperative images undergo coarse rigid registration to their corresponding
postoperative positions, followed by further non-rigid registration.
Subsequently, subtraction images are generated by subtracting the registered
preoperative images from the postoperative ones. Furthermore, to enhance the
clinical assessment of MWA treatment performance, we devise a quantitative
analysis metric to evaluate ablation efficacy by comparing differences between
tumor areas and treatment areas. To the best of our knowledge, this is the
pioneering work in the field to facilitate the assessment of MWA surgery
performance on pulmonary tumors. Extensive experiments involving 35 clinical
cases further validate the efficacy of the respiratory subtraction method. The
experimental results confirm the effectiveness of the respiratory subtraction
method and the proposed quantitative evaluation metric in assessing lung tumor
treatment.
