Interpretable Deep Learning with Multi-Scale CT for Predicting Occult Lymph Node Metastasis in Early-Stage NSCLC: A Multicenter Study.

Accurate preoperative prediction of occult lymph node metastasis (OLNM) in early-stage non-small cell lung cancer (NSCLC) is crucial for treatment planning. This study aimed to develop and validate a CT-based three-dimensional (3D) deep learning model to predict OLNM. In this retrospective, multicenter study, 900 patients from two hospitals were included and divided into a primary cohort (n = 500) for model development and an external test cohort (n = 400) for independent validation. We proposed a 3D EfficientNet model, and its diagnostic performance was compared against other benchmark deep learning architectures and four experienced radiologists. The proposed model achieved area under the receiver operating characteristic curve (AUC) of 0.8907 (95% CI 0.7878-0.9691) in the internal test set and 0.8721 (95% CI 0.8200-0.9170) in the external test cohort. This performance was superior to that of the other convolutional neural networks and the radiologists (all P < 0.05). Furthermore, interpretability analysis using Grad-CAM indicated that the model's predictions were based on distinct attention patterns. In conclusion, our 3D EfficientNet model demonstrates significant potential as a non-invasive and accurate tool for predicting OLNM in early-stage NSCLC. It can effectively support clinicians in making more precise staging and treatment decisions.