Randomized Primal-Dual Algorithm with Arbitrary Sampling: Convergence Theory and Applications to Parallel MRI

Eric Gutierrez Castillo, Claire Delplancke, Matthias Ehrhardt

Research output: Contribution to journalArticlepeer-review

Abstract

Stochastic Primal-Dual Hybrid Gradient (SPDHG) is an algorithm proposed by Chambolle et al. (SIAM J Optim 28:2783–2808) to efficiently solve a wide class of nonsmooth large-scale optimization problems. Alacaoglu et al. (SIAM J Optim 32:1288–1318, 2022) filled an important gap and proved its almost sure convergence for serial sampling. In this paper, we study the performance of SPDHG with arbitrary sampling (not necessarily serial sampling) and its applications to parallel magnetic resonance imaging (MRI), where data from different coils are randomly selected at each iteration. In order to do this, we extend the convergence result of Alacaoglu et al. and prove the almost sure convergence of SPDHG for any arbitrary sampling. We then apply SPDHG on real MRI data using a wide range of random sampling methods and compare its performance across a range of settings, including mini-batch size and step size parameters. We show that the sampling can significantly affect the convergence speed of SPDHG and that for many cases an optimal sampling can be identified.

Original languageEnglish
Article number25
JournalJournal of Mathematical Imaging and Vision
Volume67
Issue number3
Early online date17 Apr 2025
DOIs
Publication statusPublished - 17 Apr 2025

Data Availability Statement

No datasets were generated or analysed during the current study.

Funding

MJE and CD acknowledge support from the EPSRC (EP/S026045/1). MJE is also supported by EPSRC (EP/T026693/1), the Faraday Institution (EP/T007745/1) and the Leverhulme Trust (ECF-2019-478). EBG acknowledges the Mexican Council of Science and Technology (CONACyT).

FundersFunder number
Consejo Nacional de Humanidades, Ciencias y Tecnologías
Engineering and Physical Sciences Research CouncilEP/S026045/1, EP/T026693/1
Faraday InstitutionEP/T007745/1
Leverhulme TrustECF-2019-478

Keywords

  • Inverse problems
  • Parallel MRI
  • Primal-dual methods
  • Stochastic optimization

ASJC Scopus subject areas

  • Statistics and Probability
  • Modelling and Simulation
  • Condensed Matter Physics
  • Computer Vision and Pattern Recognition
  • Geometry and Topology
  • Applied Mathematics

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