Cascaded Coarse-to-Fine Neural Network for Brain Tumor Segmentation.

A cascaded framework of coarse-to-fine networks is proposed to segment brain tumor from multi-modality MR images into three subregions: enhancing tumor, whole tumor and tumor core. The framework is designed to decompose this multi-class segmentation into two sequential tasks according to hierarchical relationship among these regions. In the first task, a coarse-to-fine model based on Global Context Network predicts segmentation of whole tumor, which provides a bounding box of all three substructures to crop the input MR images. In the second task, cropped multi-modality MR images are fed into another two coarse-to-fine models based on NvNet trained on small patches to generate segmentation of tumor core and enhancing tumor, respectively. Experiments with BraTS 2020 validation set show that the proposed method achieves average Dice scores of 0.8003, 0.9123, 0.8630 for enhancing tumor, whole tumor and tumor core, respectively. The corresponding values for BraTS 2020 testing set were 0.81715, 0.88229, 0.83085, respectively.