Further Software

Several software packages developed at our institute are either suitable for both MPI and MRI or neither. These software packages are grouped in different GitHub organizations or under the account of Tobias Knopp.

The packages AbstractImageReconstruction.jl and RegularizedLeastSquares.jl contain code that is used by both MPIReco.jl and MRIReco.jl. The former contains an abstract interface for tomographic image reconstruction algorithms and code that stores and simplifies working with reconstruction algorithm parameters. The latter contains several solvers that can solve large linear systems using regularization techniques and nonlinear problem formulations.

The RedPitayaDAQServer repository contains software for use with RedPitaya's STEMlab 125-14 devices. These devices together with our software allow continuous and parallel generation and acquisition of analog signals with sampling rates up to 15.625 MH/z. In addition, multiple RedPitayas can be synchronized to form a cluster. These clusters are responsible for the analog signal handling in many of our hardware projects.

The Julia package NFFT.jl provides an implementation of the nonequidistant Fast-Fourier Transform, that is completely generic and dimension-agnostic, requiring about two to three times less code than the well-known libraries NFFT3 and FINUFFT while still being one of the fastest NFFT implementations developed to date.

    The Julia package SphericalHarmonicExpansions.jl provides methods to numerically handle real spherical harmonic expansions and their coefficients. These methods together with the Julia package MPISphericalHarmonics.jl are used in our magnetic field characterization project to investigate the magnetic fields of MPI devices.

    Contact

    Project Publications

    [191175]
    Title: RegularizedLeastSquares.jl: Modality Agnostic Julia Package for Solving Regularized Least Squares Problems.
    Written by: N. Hackelberg, M. Grosser, A. Tsanda, F. Mohn, K. Scheffler, M. Möddel, and T. Knopp
    in: <em>International Journal on Magnetic Particle Imaging</em>. (2024).
    Volume: <strong>10</strong>. Number: (1 Suppl 1),
    on pages: 1-4
    Chapter:
    Editor:
    Publisher:
    Series:
    Address:
    Edition:
    ISBN:
    how published:
    Organization:
    School:
    Institution:
    Type:
    DOI: https://doi.org/10.18416/IJMPI.2024.2403028
    URL:
    ARXIVID:
    PMID:

    Note: inproceedings, reconstruction, opensoftware, generalsoftware

    Abstract: Image reconstruction in Magnetic Particle Imaging (MPI) is an ill-posed linear inverse problem. A standard method for solving such a problem is the regularized least squares approach, which uses, a regularization function to reduce the impact of measurement noise in the reconstructed image by leveraging prior knowledge. Various optimization algorithms, including the Kazcmarz method or the Alternating Direction Method of Multipliers (ADMM), and regularization functions, such asl2or Fused Lasso priors have been employed. Therefore, the creation and implementation of cutting-edge image reconstruction techniques necessitate a robust and adaptable optimization framework. In this work, we present the open-source Julia package RegularizedLeastSquares.jl, which provides a large selection of common optimization algorithms and allows flexible inclusion of regularization functions. These features enable the package to achieve state-of-the-art image reconstruction in MPI.