BUA-Net: Boundary and uncertainty-aware attention network for lumbar multi-region magnetic resonance imaging segmentation

Abstract

Background and Objective:Multi-region segmentation by axial lumbar magnetic resonance imaging (MRI) is important for the diagnosis of lumbar spinal stenosis (LSS) and lumbar disc herniation (LDH) disease. Deep learning-based methods have been widely used in this field, but the segmentation task is still challenging due to intra-class grayscale unevenness, inter-class low contrast and unclear boundaries. Methods:To solve the above problems, we propose a novel boundary and uncertainty-aware attention network (BUA-Net). It is structured around a single encoder and two decoders, each dedicated to either multi-region or boundary segmentation. We use an uncertainty-aware attention (UA) module to extract regions with large segmentation uncertainty and generate an attention mask. The learning and supervisory capabilities of the model are enhanced by a fine seg (FS) module and an attention supervision loss (ASL) in the boundaries and blurred regions. Moreover, a multi-scale spatial channel attention (MSCA) module is proposed that refines the high-level features without increasing any layers. Results:The results of the BUA-Net experiments were tested against seven networks and showed a 0.26% improvement in Dice scores, a 0.86% improvement in precision, and a 0.2% improvement in recall. In metrics related to boundary segmentation effectiveness, our method nearly matches the state-of-the-art in the ASD metric, surpasses it by 2.32 in the 95HD metric, and leads by 2.04, 2.68, and 1.22 in the IVD, TS, and PE categories, respectively. Conclusions:The experimental results demonstrate that our proposed method outperforms other state-of-the-art methods and shows excellent segmentation ability in the boundaries and blurred regions.