Deeply supervised 3D fully convolutional networks with group dilated convolution for automatic MRI prostate segmentation

• Type of Material: Article
• Authors: Bo Wang, Emory University; Yang Lei, Emory University; Sibo Tian, Emory University; Tonghe Wang, Emory University; Yingzi Liu, Emory University; Pretesh Patel, Emory University; Ashesh Jani, Emory University; Hui Mao, Emory University; Walter Curran Jr, Emory University; Tian Liu, Emory University; Xiaofeng Yang, Emory University
• Language: English
• Date: 2019-04-01
• Publisher: Wiley
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2019 American Association of Physicists in Medicine
• Final Published Version (URL): http://dx.doi.org/10.1002/mp.13416
• Title of Journal or Parent Work: Medical Physics
• Volume: 46
• Issue: 4
• Start Page: 1707
• End Page: 1718
• Grant/Funding Information: We are also grateful for the GPU support from NVIDIA Corporation.; This research is supported in part by the National Cancer Institute of the National Institutes of Health under Award Number R01CA215718 (XY), the Department of Defense (DoD) Prostate Cancer Research Program (PCRP) Award W81XWH-13-1-0269 (XY), W81XWH-17-1-0438 (TL) and W81XWH-17-1-0439 (AJ) and Dunwoody Golf Club Prostate Cancer Research Award (XY), a philanthropic award provided by the Winship Cancer Institute of Emory University.
• Keywords: Framework; Synthetic CT; Life Sciences & Biomedicine; Radiology, Nuclear Medicine & Medical Imaging; group dilated convolution; fully convolutional networks (FCN); 3D prostate segmentation; Image; deeply supervised mechanism; Science & Technology
• Research Categories: Health Sciences, Radiology; Engineering, Biomedical; Health Sciences, Oncology

Abstract

Purpose: Reliable automated segmentation of the prostate is indispensable for image-guided prostate interventions. However, the segmentation task is challenging due to inhomogeneous intensity distributions, variation in prostate anatomy, among other problems. Manual segmentation can be time-consuming and is subject to inter- and intraobserver variation. We developed an automated deep learning-based method to address this technical challenge. Methods: We propose a three-dimensional (3D) fully convolutional networks (FCN) with deep supervision and group dilated convolution to segment the prostate on magnetic resonance imaging (MRI). In this method, a deeply supervised mechanism was introduced into a 3D FCN to effectively alleviate the common exploding or vanishing gradients problems in training deep models, which forces the update process of the hidden layer filters to favor highly discriminative features. A group dilated convolution which aggregates multiscale contextual information for dense prediction was proposed to enlarge the effective receptive field of convolutional neural networks, which improve the prediction accuracy of prostate boundary. In addition, we introduced a combined loss function including cosine and cross entropy, which measures similarity and dissimilarity between segmented and manual contours, to further improve the segmentation accuracy. Prostate volumes manually segmented by experienced physicians were used as a gold standard against which our segmentation accuracy was measured. Results: The proposed method was evaluated on an internal dataset comprising 40 T2-weighted prostate MR volumes. Our method achieved a Dice similarity coefficient (DSC) of 0.86 ± 0.04, a mean surface distance (MSD) of 1.79 ± 0.46 mm, 95% Hausdorff distance (95%HD) of 7.98 ± 2.91 mm, and absolute relative volume difference (aRVD) of 15.65 ± 10.82. A public dataset (PROMISE12) including 50 T2-weighted prostate MR volumes was also employed to evaluate our approach. Our method yielded a DSC of 0.88 ± 0.05, MSD of 1.02 ± 0.35 mm, 95% HD of 9.50 ± 5.11 mm, and aRVD of 8.93 ± 7.56. Conclusion: We developed a novel deeply supervised deep learning-based approach with a group dilated convolution to automatically segment the MRI prostate, demonstrated its clinical feasibility, and validated its accuracy against manual segmentation. The proposed technique could be a useful tool for image-guided interventions in prostate cancer.