QN-Mixer: A Quasi-Newton MLP-Mixer Model for Sparse-View CT Reconstruction
<|reference_start|>QN-Mixer: A Quasi-Newton MLP-Mixer Model for Sparse-View CT Reconstruction: Inverse problems span across diverse fields. In medical contexts, computed tomography (CT) plays a crucial role in reconstructing a patient's internal structure, presenting challenges due to artifacts caused by inherently ill-posed inverse problems. Previous research advanced image quality via post-processing and deep unrolling algorithms but faces challenges, such as extended convergence times with ultra-sparse data. Despite enhancements, resulting images often show significant artifacts, limiting their effectiveness for real-world diagnostic applications. We aim to explore deep second-order unrolling algorithms for solving imaging inverse problems, emphasizing their faster convergence and lower time complexity compared to common first-order methods like gradient descent. In this paper, we introduce QN-Mixer, an algorithm based on the quasi-Newton approach. We use learned parameters through the BFGS algorithm and introduce Incept-Mixer, an efficient neural architecture that serves as a non-local regularization term, capturing long-range dependencies within images. To address the computational demands typically associated with quasi-Newton algorithms that require full Hessian matrix computations, we present a memory-efficient alternative. Our approach intelligently downsamples gradient information, significantly reducing computational requirements while maintaining performance. The approach is validated through experiments on the sparse-view CT problem, involving various datasets and scanning protocols, and is compared with post-processing and deep unrolling state-of-the-art approaches. Our method outperforms existing approaches and achieves state-of-the-art performance in terms of SSIM and PSNR, all while reducing the number of unrolling iterations required.<|reference_end|>
@article{ayad2024qn-mixer:,
    title={QN-Mixer: A Quasi-Newton MLP-Mixer Model for Sparse-View CT
  Reconstruction},
    author={Ishak Ayad, Nicolas Larue, Ma"i K. Nguyen},
    journal={arXiv preprint arXiv:2402.17951},
    year={2024},
    archivePrefix={arXiv},
    eprint={2402.17951},
    primaryClass={eess.IV cs.CV}
}