Assessment and Prognostic Value of Immediate Changes in Post-Ablation Intratumor Density Heterogeneity of Pulmonary Tumors via Radiomics-Based Computed Tomography Features.

Bo Liu,Ligang Xing,Haipeng Jia,Shuying Li,Xinzhe Dong,Xiaorong Sun,Hong Liu,Wei Zhou,Jing Sun,Chunhai Li

doi:10.3389/fonc.2021.615174

Abstract

ObjectivesTo retrospectively observe the instantaneous changes in intratumor density heterogeneity after microwave ablation (MWA) of lung tumors and to determine their prognostic value in predicting treatment response and local tumor progression (LTP).MethodsPre- and post-MWA computed tomography (CT) images of 50 patients (37-males; 13-females; mean-age 65.9 ± 9.7y, 39 primary and 11 metastasis) were analyzed to evaluate changes in intratumor density. Global, regional, and local scale radiomics features were extracted to assess intratumor density heterogeneity. In four to six weeks, chest enhanced CT was used as the baseline evaluation of treatment response. The correlations between the parametric variation immediately after ablation and the visual score of ablation response (Rvisu) were analyzed by nonparametric Spearman correlation analysis. The 1-year LTP discrimination power was assessed using the area under the receiver operating characteristic (ROC) curves. A Cox proportional hazards regression model was used to identify the independent prognostic features.ResultsAlthough no significant volume changes were observed after ablation, the radiomics parameters changed in different directions and degrees. The mean intensity value from baseline CT image was 30.3 ± 23.2, and the post-MWA CT image was -60.9 ± 89.8. The ratio of values change was then calculated by a unified formulation. The largest increase (522.3%) was observed for cluster prominence, while the mean CT value showed the largest decline (321.4%). The pulmonary tumors had a mean diameter of 3.4 ± 0.8 cm. Complete ablation was documented in 36 patients. Significant correlations were observed between Rvisu and quantitative features. The highest correlations were observed for changes in local features after MWA, with r ranging from 0.594 to 0.782. LTP developed in 22 patients. The Cox regression model revealed Δcontrast% and response score as independent predictors (Δcontrast%: odds ratio [OR]=5.61, p=0.001; Rvisu: OR=1.73, p=0019). ROC curve analysis showed that Δcontrast% was a better predictor of 1-year LTP. with higher sensitivity (83.5% vs. 71.2%) and specificity (87.1% vs. 76.8%) than those for Rvisu.ConclusionsThe changes in intratumor density heterogeneity after MWA could be characterized by analysis of radiomics features. Real-time density changes could predict treatment response and LTP in patients with pulmonary tumors earlier, especially for tumors with larger diameters.

Highlights

Primary lung cancer is the most common cancer and the leading cause of cancer-related mortality in China and worldwide [1]
Patients were recruited based on the following eligibility criteria [1]: patients who were referred to our radiology department for microwave ablation (MWA) of lung tumors [2]; malignant lung tumors confirmed by histological or cytological diagnosis [3]; re-examination by chest enhanced computed tomography (CT) 4–6 weeks after the procedure, which was used as the baseline for evaluation [4]; tumor volume ≥2.5 cm3; and [5] adequate normal organ function
No severe lung infections or other intraprocedural complications occurred in any patient during the follow-up

Summary

Introduction

Primary lung cancer is the most common cancer and the leading cause of cancer-related mortality in China and worldwide [1]. The abundant blood supply and special growth microenvironment in lung tissue favor metastatic development. Owing to this permissive environment, the lungs are one of the most common sites of metastases, with 30% of patients with malignant solid tumors developing pulmonary metastases [2]. Compared to RFA, MWA is reportedly a more effective treatment for lung tumors [4,5,6]. Chest enhanced computed tomography (CT) examinations are often performed 4–6 weeks after the procedure to evaluate the local efficacy of the treatment. The earlier evaluation of the local efficacies of MWA could allow more timely interventions, such as second MWA and radiation therapy, which might help to reduce tumor load and prolong overall survival [9]

Objectives

Methods

Results

Conclusion