Global k-Space Interpolation for Dynamic MRI Reconstruction using Masked Image Modeling

TL;DR

This paper introduces a novel Transformer-based method called k-GIN for interpolating undersampled k-space data in dynamic MRI, improving reconstruction quality and robustness over existing image-domain regularizer methods.

Contribution

The work proposes a new k-space interpolation approach using masked image modeling and Transformer architecture, with a refinement module for better high-frequency detail recovery.

Findings

Outperforms baseline methods in quantitative metrics.

Achieves higher robustness with highly-undersampled data.

Demonstrates superior generalizability across different cases.

Abstract

In dynamic Magnetic Resonance Imaging (MRI), k-space is typically undersampled due to limited scan time, resulting in aliasing artifacts in the image domain. Hence, dynamic MR reconstruction requires not only modeling spatial frequency components in the x and y directions of k-space but also considering temporal redundancy. Most previous works rely on image-domain regularizers (priors) to conduct MR reconstruction. In contrast, we focus on interpolating the undersampled k-space before obtaining images with Fourier transform. In this work, we connect masked image modeling with k-space interpolation and propose a novel Transformer-based k-space Global Interpolation Network, termed k-GIN. Our k-GIN learns global dependencies among low- and high-frequency components of 2D+t k-space and uses it to interpolate unsampled data. Further, we propose a novel k-space Iterative Refinement Module (k-IRM) to enhance the high-frequency components learning. We evaluate our approach on 92 in-house 2D+t cardiac MR subjects and compare it to MR reconstruction methods with image-domain regularizers. Experiments show that our proposed k-space interpolation method quantitatively and qualitatively outperforms baseline methods. Importantly, the proposed approach achieves substantially higher robustness and generalizability in cases of highly-undersampled MR data. For video presentation, poster, GIF results and code please check our project page: https://jzpeterpan.github.io/k-gin.github.io/.