Validation of the BRODERS classifier (Benign versus aggressive nODule Evaluation using Radiomic Stratification), a novel high-resolution computed tomography-based radiomic classifier for indeterminate pulmonary nodules
IntroductionImplementation of low-dose chest computed tomography (CT) lung cancer screening and the ever-increasing use of cross-sectional imaging are resulting in the identification of many screen- and incidentally detected indeterminate pulmonary nodules. While the management of nodules with low or high pretest probability of malignancy is relatively straightforward, those with intermediate pretest probability commonly require advanced imaging or biopsy. Non-invasive risk stratification tools are highly desirable.MethodsWe previously developed the BRODERS classifier (Benign versus aggRessive nODule Evaluation using Radiomic Stratification), a conventional predictive radiomic model based on 8 imaging features capturing nodule location, shape, size, texture and surface characteristics. Herein we report its external validation using a dataset of incidentally identified lung nodules (Vanderbilt University Lung Nodule Registry) in comparison to the Brock model. Area under the curve (AUC), as well as sensitivity, specificity, negative and positive predictive values were calculated.ResultsFor the entire Vanderbilt validation set (n=170, 54% malignant), the AUC was 0.87 (95% CI=0.81–0.92) for the Brock model and 0.90 (95% CI=0.85–0.94) for the BRODERS model. Using the optimal cutoff determined by Youden's Index, the sensitivity was 92.3%, the specificity was 62.0%, the positive (PPV) and negative predictive values (NPV) were 73.7% and 87.5%, respectively. For nodules with intermediate pre-test probability of malignancy, Brock score of 5–65% (n=97), the Sensitivity and Specificity were 94% and 46%, the PPV was 78.4% and the NPV was 79.2%, respectively.ConclusionsThe BRODERS radiomic predictive model performs well on an independent dataset and may facilitate the management of indeterminate pulmonary nodules.