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. 2022 Oct 26:16:975862.
doi: 10.3389/fnins.2022.975862. eCollection 2022.

New multiple sclerosis lesion segmentation and detection using pre-activation U-Net

Affiliations

New multiple sclerosis lesion segmentation and detection using pre-activation U-Net

Pooya Ashtari et al. Front Neurosci. .

Abstract

Automated segmentation of new multiple sclerosis (MS) lesions in 3D MRI data is an essential prerequisite for monitoring and quantifying MS progression. Manual delineation of such lesions is time-consuming and expensive, especially because raters need to deal with 3D images and several modalities. In this paper, we propose Pre-U-Net, a 3D encoder-decoder architecture with pre-activation residual blocks, for the segmentation and detection of new MS lesions. Due to the limited training set and the class imbalance problem, we apply intensive data augmentation and use deep supervision to train our models effectively. Following the same U-shaped architecture but different blocks, Pre-U-Net outperforms U-Net and Res-U-Net on the MSSEG-2 dataset, achieving a Dice score of 40.3% on new lesion segmentation and an F1 score of 48.1% on new lesion detection. The codes and trained models are publicly available at https://github.com/pashtari/xunet.

Keywords: U-Net; multiple sclerosis; new lesions; pre-activation; segmentation.

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Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

Figure 1
Figure 1
Qualitative results on new MS lesion segmentation. The three examples are from three different patients in the test set. The new lesions are shown in red in the segmentation maps. The new lesions circled in yellow (rows 2-3 and column 6) are successfully detected only by Pre-U-Net, while the new lesion circled in blue (row 3 and column 3) is not captured by any of the models, representing a very difficult case. The patient-wise Dice score for each example is displayed on the segmentation map.
Figure 2
Figure 2
The proposed encoder-decoder architecture. The two lower-resolution auxiliary maps are only used in the training phase as deep supervisions.
Figure 3
Figure 3
The proposed blocks. (A) U-Net block. (B) Res-U-Net block. (C) Pre-U-Net block.
Figure 4
Figure 4
Comparison of different models on the MSSEG-2 test set. (A–C) Show box plots of Dice score (%), F1 score (%), and Hausdorff Distance (mm), respectively. The asterisks indicate how significantly a model score differs from those of the other baselines when using a pairwise Wilcoxon signed-rank test (*p-value < 0.05, **p-value < 0.01).

References

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