Robust 3D Brain MRI Inpainting with Random Masking Augmentation

The ASNR-MICCAI BraTS-Inpainting Challenge was established to mitigate dataset biases that limit deep learning models in the quantitative analysis of brain tumor MRI. This paper details our submission to the 2025 challenge, a novel deep learning framework for synthesizing healthy tissue in 3D scans. The core of our method is a U-Net architecture trained to inpaint synthetically corrupted regions, enhanced with a random masking augmentation strategy to improve generalization. Quantitative evaluation confirmed the efficacy of our approach, yielding an SSIM of 0.873±0.004, a PSNR of 24.996±4.694, and an MSE of 0.005±0.087 on the validation set. On the final online test set, our method achieved an SSIM of 0.919±0.088, a PSNR of 26.932±5.057, and an RMSE of 0.052±0.026. This performance secured first place in the BraTS-Inpainting 2025 challenge and surpassed the winning solutions from the 2023 and 2024 competitions on the official leaderboard.