Fig. 1. Structural diagram of DenseBlock

Fig. 2. Dilated convolutions under different dilation rates when convolution kernel is 3×3. (a) Dilation rate is 1; (b) dilation rate is 2

Fig. 3. Iterative process of CRF

Fig. 4. Structure of CRF-RNN

Fig. 5. DenseU-net-CRFRNN model

Fig. 6. Four modal slice images. (a) T1 modal slice image; (b) T1c modal slice image; (c) T2 modal slice image; (d) Flair modal slice image

Fig. 7. Comparison between results segmented by different models and annotations of experts. (a) Two-dimensional brain tumor slices; (b) annotations of experts; (c) results segmented by DenseU-net model; (d) results segmented by DenseU-net-CRFRNN model

Fig. 8. Segmentation result of DenseU-net model

Fig. 9. Segmentation result of DenseU-net-CRFRNN model