Automatic Segmentation of Pulmonary Lobes in Pulmonary CT Images using Atlas-based Unsupervised Learning Network

Pulmonary lobes segmentation of pulmonary CT images is important for assistant therapy and diagnosis of pulmonary disease in many clinical tasks. Recently supervised deep learning methods are applied widely in fast automatic medical image segmentation including pulmonary lobes segmentation of pulmonary CT images. However, they require plenty of ground truth due to their supervised learning scheme, which are always difficult to realize in practice. To address this issue, in this study we extend an existed unsupervised learning network with an extra pulmonary mask constraint to develop a deformable pulmonary lobes atlas and apply it for fast automatic segmentation of pulmonary lobes in pulmonary CT images. The experiment on 40 pulmonary CT images shows that our method can segment the pulmonary lobes in seconds, and achieve average Dice of 0.906 ± 0.044 and average surface distance of 0.495 ± 0.380 mm, which outperforms the state-of-the-art methods in segmentation accuracy. Our method successfully combines the advantages of both deformable atlas and unsupervised learning for automatic segmentation and ensures the consistent and topology preserving of pulmonary lobes without any postprocessing.