Multi-Task Learning for Lung Nodule Classification on Chest CT

Lung cancer is one of the leading causes of death over the world. Detecting and identifying malignant nodules on chest computed tomography (CT) plays an important role in the diagnosis and treatment of lung cancer. Computer-aided diagnosis (CAD) systems have been developed to identify lung nodules. However, the problem of a high false positive rate is still not well solved. In this paper, we propose a novel multi-task convolutional neural network (MT-CNN) framework to identify malignant nodules from benign nodules on chest CT scans. MT-CNN learns three-dimensional (3-D) lung nodule characteristics from nine two-dimensional (2-D) views, which are decomposed from different angles of each nodule. Each of 2-D MT-CNN model consists of two branches, one is the nodule classification branch (main task) and the other is the image reconstruction branch (auxiliary task). The motivation of the auxiliary task is to preserve more microscopic information in the hierarchical structure of CNN, which is beneficial to malignant nodule identification. The final classification result is obtained by integrating nine 2-D models. We test our method on the benchmark LUNA-16 and LIDC-IDRI datasets and compare it with state-of-the-art models. MT-CNN achieves the lowest false positive rate (3.2%) and highest AUC (97.3%) in LUNA-16 dataset and achieves an AUC of 95.59% in LIDC-IDRI. These results demonstrate the advantage of our method.