LG-Net: Lesion Gate Network for multiple sclerosis lesion inpainting

Multiple sclerosis (MS) is an immune-mediated neurodegenerative disease that results in progressive damage to the brain and spinal cord. Volumetric analysis of the brain tissues with Magnetic Resonance Imaging (MRI) is essential to monitor the progression of the disease. However, the presence of focal brain pathology leads to tissue misclassifications, and has been traditionally addressed by “inpainting” MS lesions with voxel intensities sampled from surrounding normal-appearing white matter. Based on the characteristics of brain MRIs and MS lesions, we propose a Lesion Gate Network (LG-Net) for MS lesion inpainting with a learnable dynamic gate mask integrated with the convolution blocks to dynamically select the features for a lesion area defined by a noisy lesion mask. We also introduce a lesion gate consistency loss to support the training of the gated lesion convolution by minimizing the differences between the features selected from the brain with and without lesions. We evaluated the proposed model on both public and in-house data and our method demonstrated a faster and superior performance than the state-of-the-art inpainting techniques developed for MS lesion and general image inpainting tasks.