Automatic pulmonary ground‐glass opacity nodules detection and classification based on 3D neural network

Purpose Pulmonary ground‐glass opacity (GGO) nodules are more likely to be malignant compared with solid solitary nodules. Due to indistinct boundaries of GGO nodules, the detection and diagnosis are challenging for doctors. Therefore, designing an automatic GGO nodule detection and classification scheme is significantly essential. Methods In this paper, we proposed a two‐stage 3D GGO nodule detection and classification framework. First, we used a pretrained 3D U‐Net to extract lung parenchyma. Second, we adapted the architecture of Mask region‐based convolutional neural networks (RCNN) to handle 3D medical images. The 3D model was then applied to detect the locations of GGO nodules and classify lesions (benign or malignant). The class‐balanced loss function was also used to balance the number of benign and malignant lesions. Finally, we employed a novel false positive elimination scheme called the feature‐based weighted clustering (FWC) to promote the detection accuracy further. Results The experiments were conducted based on fivefold cross‐validation with the imbalanced data set. Experimental results showed that the mean average precision could keep a high level (0.5182) in the phase of detection. Meanwhile, the false positive rate was effectively controlled, and the competition performance metric (CPM) reached 0.817 benefited from the FWC algorithm. The comparative statistical analyses with other deep learning methods also proved the effectiveness of our proposed method. Conclusions We put forward an automatic pulmonary GGO nodules detection and classification framework based on deep learning. The proposed method locate and classify nodules accurately, which could be an effective tool to help doctors in clinical diagnoses.