Implicit Neural Representation for MRI Parallel Imaging Reconstruction

Magnetic resonance imaging (MRI) always suffers from long acquisition times. Parallel imaging (PI) is one solution to reduce scan time by periodically skipping certain K-space lines and then reconstructing high-quality images from undersampled measurements. Recently, implicit neural representation (INR) has emerged as a new deep learning method that represents an object as a continuous function of spatial coordinates, and this function is normally parameterized by a multilayer perceptron (MLP). In this paper, we propose a novel MRI PI reconstruction method based on INR, which represents the reconstructed fully-sampled images as the function of voxel coordinates and prior feature vectors of undersampled images to overcome the generalization problem of INR. Specifically, we introduce a scale-embedded encoder to produce scale-independent voxel-specific features from MR images with different undersampling scales and then concatenate with coordinate vectors to recover fully-sampled MR images, thus achieving multiple scale reconstructions. The performance of the proposed method was assessed by experimenting with publicly available MRI datasets and was compared with other reconstruction methods. Our quantitative evaluation demonstrates the superiority of the proposed method over alternative reconstruction methods.