Unrolled Networks are Conditional Probability Flows in MRI Reconstruction

Fuente: arXiv
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Autori principali: Qi, Kehan, Gupta, Saumya, Hu, Xiaoling, Hu, Qingqiao, Lyu, Weimin, Chen, Chao
Natura: Preprint
Pubblicazione: 2025
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author Qi, Kehan
Gupta, Saumya
Hu, Xiaoling
Hu, Qingqiao
Lyu, Weimin
Chen, Chao
author_facet Qi, Kehan
Gupta, Saumya
Hu, Xiaoling
Hu, Qingqiao
Lyu, Weimin
Chen, Chao
contents Unrolled networks have been widely used for Magnetic Resonance Imaging (MRI) reconstruction due to their efficiency. However, they typically exhibit unstable output quality across cascades, resulting in sub-optimal final reconstruction results. In this work, we address this inherent limitation of unrolled networks, drawing inspiration from recent Flow Matching paradigm. We first theoretically prove that unrolled networks are discretizations of conditional probability flows. This connection shows that unrolled networks and Flow Matching are analogous in MRI reconstruction. Building upon this insight, we propose FLow-Aligned Training (FLAT), which (1) derives important cascade parameters from the Flow Matching discretization; and (2) aligns intermediate reconstructions with the ideal Flow Matching trajectory to improve cascade iteration stability and convergence. Experiments on three MRI datasets show that FLAT results in a stable trajectory across sub-networks, improving the quality of the final reconstruction.
format Preprint
id arxiv_https___arxiv_org_abs_2512_03020
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Unrolled Networks are Conditional Probability Flows in MRI Reconstruction
Qi, Kehan
Gupta, Saumya
Hu, Xiaoling
Hu, Qingqiao
Lyu, Weimin
Chen, Chao
Computer Vision and Pattern Recognition
Unrolled networks have been widely used for Magnetic Resonance Imaging (MRI) reconstruction due to their efficiency. However, they typically exhibit unstable output quality across cascades, resulting in sub-optimal final reconstruction results. In this work, we address this inherent limitation of unrolled networks, drawing inspiration from recent Flow Matching paradigm. We first theoretically prove that unrolled networks are discretizations of conditional probability flows. This connection shows that unrolled networks and Flow Matching are analogous in MRI reconstruction. Building upon this insight, we propose FLow-Aligned Training (FLAT), which (1) derives important cascade parameters from the Flow Matching discretization; and (2) aligns intermediate reconstructions with the ideal Flow Matching trajectory to improve cascade iteration stability and convergence. Experiments on three MRI datasets show that FLAT results in a stable trajectory across sub-networks, improving the quality of the final reconstruction.
title Unrolled Networks are Conditional Probability Flows in MRI Reconstruction
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2512.03020