Image fusion for intraoperative evaluation of microwave ablation in non-small cell lung cancer: a retrospective cohort study.

Background: Patients with early-stage non-small cell lung cancer (NSCLC) who are intolerant to surgery have a poor prognosis. Microwave ablation is an effective treatment method. However, the density of the lesion may occasionally be similar to that of the ablation zone, thus rendering it difficult to identify the relative position of the lesion and ablation zone during ablation. This study aimed to use image fusion technology to help confirm the relative position of lesions and ablation zones and to facilitate immediate assessment of the residual lesions. Methods: This retrospective study was conducted in Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, between August 2019 and August 2021, and consecutively included patients who had undergone computed tomography (CT)-guided percutaneous microwave ablation for NSCLC. A single radiologist manually fused the intraoperative CT images alignment of the lesions. Two other clinicians examined the postoperative CT images and the fused CT images to determine whether a lesion remained and to measure the minimum ablative margin (MAM). One of the clinicians assessed the complete ablation rate on CT images 6 months after ablation. The Chi-squared test was used to calculate the kappa coefficients between the two investigators. Binary logistic regression was used to analyze the correlation between each characteristic parameter of the lesion and image quality. The clinicians involved in this study all had over 10 years of work experience. Results: Among the 29 participants, comprising 32 lesions retrospectively included (median age 65 years; 41.4% male), the image fusion success rate was 96.88%, and the median fusion time was10 minutes. The rate of accurate recognition for the relative position of pulmonary nodules and ablation zone on original CT images of the two physicians was 7.52% and 12.90%, respectively, while that achieved from the fused CT images was 87.1% and 86.0%, respectively; in agreement testing, the kappa coefficient between the physicians was 0.859 (P<0.001). The MAM on fused images was 3.05±1.35 mm (range, 1.1-6.7 mm). The quality of fused images was positively correlated with the CT values of focus (P=0.009). The complete ablation rate (93.5%) indicated by immediate image fusion post ablation was consistent with that determined by CT images after 6 months after ablation, with 100% sensitivity and specificity. Conclusions: Image fusion is a valuable strategy for evaluating whether intraoperative ground glass nodules are completely ablated by microwave ablation.