The Reconstruction of Magnetic Particle Imaging: Current Approaches Based on the System Matrix

Abstract

Magnetic particle imaging (MPI) is a novel non-invasive molecular imaging technology that images the distribution of superparamagnetic iron oxide nanoparticles (SPIONs). It is not affected by imaging depth, with high sensitivity, high resolution, and no radiation. The MPI reconstruction with high precision and high quality is of enormous practical importance, and many studies have been conducted to improve the reconstruction accuracy and quality. MPI reconstruction based on the system matrix (SM) is an important part of MPI reconstruction. In this review, the principle of MPI, current construction methods of SM and the theory of SM-based MPI are discussed. For SM-based approaches, MPI reconstruction mainly has the following problems: the reconstruction problem is an inverse and ill-posed problem, the complex background signals seriously affect the reconstruction results, the field of view cannot cover the entire object, and the available 3D datasets are of relatively large volume. In this review, we compared and grouped different studies on the above issues, including SM-based MPI reconstruction based on the state-of-the-art Tikhonov regularization, SM-based MPI reconstruction based on the improved methods, SM-based MPI reconstruction methods to subtract the background signal, SM-based MPI reconstruction approaches to expand the spatial coverage, and matrix transformations to accelerate SM-based MPI reconstruction. In addition, the current phantoms and performance indicators used for SM-based reconstruction are listed. Finally, certain research suggestions for MPI reconstruction are proposed, expecting that this review will provide a certain reference for researchers in MPI reconstruction and will promote the future applications of MPI in clinical medicine.

Recent Metal Nanotheranostics for Cancer Diagnosis and Therapy: A Review

“…In recent years, there has been an increasing amount of literature on using magnetic particle imaging (MPI) for tumor detection [88]. MPI is a novel noninvasive molecular imaging technology that images the bio-distribution of SPIONs [88].…”

“…In recent years, there has been an increasing amount of literature on using magnetic particle imaging (MPI) for tumor detection [88]. MPI is a novel noninvasive molecular imaging technology that images the bio-distribution of SPIONs [88]. MPI is a favorable tool for cancer diagnosis, as it offers the advantages of zero background signal, zero signal reduction with increasing tissue depth, quantitative linearity, and high sensitivity.…”

Recent developments of the reconstruction in magnetic particle imaging

“…Convergence has been reported to occur within ten iterations of the Kaczmarz method [ 52 ]. Therefore, the state-of-the-art method for SM-based reconstruction is the Tikhonov regularization solved by the Kaczmarz method [ 53 ]. In recent years, many Kaczmarz-related Tikhonov regularization solutions have emerged in the field of MPI reconstruction [ 3 , 50 , 54 ].…”

Magnetic Nanoparticle Imaging: Insight on the Effects of Magnetic Interactions and Hysteresis of Tracers

“…In an MPI scanning operation, the high-frequency signal picked up at the instantaneous FFP is determined not only by the nanoparticles actually located at the FFP (where the bias field is vanishingly small) but also by the ones present in neighboring regions of tissue where the bias field is not strong enough to saturate the particle magnetization, making it necessary to solve a complex inversion problem in order to properly analyze the convoluted signal generated by the target. ,, The higher the gradient of the bias field, the less convoluted is the picked-up signal. In the limit of an infinite gradient, all particles not precisely located at the FFP are magnetically saturated and therefore produce no magnetic signal at the driving field frequency.…”