Joint Reconstruction of Tracer Distribution and Background in Magnetic Particle Imaging

Straub, M.; Schulz, Volkmar

doi:10.1109/tmi.2017.2777878

Cited by 34 publications

(35 citation statements)

References 32 publications

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“…These deviations can only partly be attributed to technical issues, such as heating of hardware components and thermal drifts of the background signal, which could have caused the small deviations below 5% in the control experiment (as determined from injection of PBS without cells). The impact of thermal drifts could be minimized by an advanced background signal removal technique 34,35 . We assume the main reason for the deviation was caused by MNPs whose magnetic properties deviate from the states "free MNP" and "cell-bound MNPs", which we used in this proof-of-principle study.…”

Section: Discussionmentioning

confidence: 99%

Cellular uptake of magnetic nanoparticles imaged and quantified by magnetic particle imaging

Paysen

Loewa

Stach

et al. 2020

Sci Rep

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Magnetic particle imaging (Mpi) is a non-invasive, non-ionizing imaging technique for the visualization and quantification of magnetic nanoparticles (MNPs). The technique is especially suitable for cell imaging as it offers zero background contribution from the surrounding tissue, high sensitivity, and good spatial and temporal resolutions. Previous studies have demonstrated that the dynamic magnetic behaviour of MNPs changes during cellular binding and internalization. In this study, we demonstrate how this information is encoded in the Mpi imaging signal. through Mpi imaging we are able to discriminate between free and cell-bound MNPs in reconstructed images. This technique was used to image and quantify the changes that occur in-vitro when free Mnps come into contact with cells and undergo cellular-uptake over time. The quantitative MPI results were verified by colorimetric measurements of the iron content. The results showed a mean relative difference between the MPI results and the reference method of 23.8% for the quantification of cell-bound MNPs. With this technique, the uptake of MNPs in cells can be imaged and quantified directly from the first MNP cell contact, providing information on the dynamics of cellular uptake. Magnetic particle imaging (MPI) is a non-invasive technique capable of determining the spatial distribution of magnetic nanoparticles (MNPs) both in-vivo and in-vitro 1. MPI achieves imaging and quantification detecting the non-linear dynamic magnetic response of MNPs exposed to multiple superimposed static and dynamic magnetic fields with a submillimetre spatial resolution. No background signals are generated by bone or tissue. The technique uses non-ionizing radiation and non-toxic nanoparticles to prevent tissue damage. MPI shows great potential for different biomedical applications, such as angiography, stem cell tracking, diagnosis of inflammatory diseases and cancer 2-11. In inflammation-associated diseases, including cancer, MNPs accumulate preferentially in diseased tissue as a result of leaky vasculature thereby enabling imaging with MRI and MPI 12-16. In diseased tissue, MNPs accumulate mainly in macrophages 17,18. These phagocytic cells are a hallmark of tissue inflammation and their quantity is considered a marker of the severity of the disease 19-21. The magnetic response generated by MNPs is severely influenced by their local environment. In this respect, the changing magnetic properties of MNPs induced by their interaction with cells are a relevant factor for MPI. Previous studies using magnetic particle spectroscopy (MPS), have described and quantified the changes that occur in the dynamic magnetization of certain MNP systems upon interaction with living cells 22-26. These effects may be caused by a variety of factors including the aggregation of particles in the surrounding solution, within the extra-cellular matrix or within various intracellular compartments. "Size-filtering" during cellular uptake and an increase in dipole-dipole interactions caused by a lower separati...

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Section: Discussionmentioning

confidence: 99%

Cellular uptake of magnetic nanoparticles imaged and quantified by magnetic particle imaging

Paysen

Loewa

Stach

et al. 2020

Sci Rep

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“…This method is only suitable for a sufficiently small time interval between the background measurement and sample measurement. Straub and Schulz performed MPI reconstruction by adopting the traditional linear interpolation method with the Kaczmarz algorithm, and proved that there is a significant difference between the two reconstructed images at a time interval of 55 min [ 39 ].…”

Section: Current Sm-based Mpi Reconstruction Methodsmentioning

confidence: 99%

“…The measurement-based approach is a common way to obtain the SM [ 6 , 38 , 39 ]. To measure the SM of a MPI scanner, a cube-shaped calibration sample is used that is similar to electrical capacitance tomography (ECT) [ 40 ].…”

Section: The Theory Of Sm-based Mpimentioning

confidence: 99%

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

et al. 2021

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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.

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“…In 2012, Conolly and Goodwill from the University of California, Berkeley, built the MPI scanner based on the same imaging principle but different scanning techniques and reconstruction approaches. Other researchers from the United States, Japan, Italy, and other countries [ 19 , 20 , 21 , 22 , 23 , 24 , 25 ] have also researched different aspects of, and contributed to, its development. With continuous improvement of MPI, significant progress has also been made in the applications of MPI in various fields.…”

Section: Introductionmentioning

confidence: 99%

The Applications of Magnetic Particle Imaging: From Cell to Body

Han

Liu

et al. 2020

Diagnostics

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Magnetic particle imaging (MPI) is a cutting-edge imaging technique that is attracting increasing attention. This novel technique collects signals from superparamagnetic nanoparticles as its imaging tracer. It has characteristics such as linear quantitativity, positive contrast, unlimited penetration, no radiation, and no background signal from surrounding tissue. These characteristics enable various medical applications. In this paper, we first introduce the development and imaging principles of MPI. Then, we discuss the current major applications of MPI by dividing them into four categories: cell tracking, blood pool imaging, tumor imaging, and visualized magnetic hyperthermia. Even though research on MPI is still in its infancy, we hope this discussion will promote interest in the applications of MPI and encourage the design of tracers tailored for MPI.

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Joint Reconstruction of Tracer Distribution and Background in Magnetic Particle Imaging

Cited by 34 publications

References 32 publications

Cellular uptake of magnetic nanoparticles imaged and quantified by magnetic particle imaging

Cellular uptake of magnetic nanoparticles imaged and quantified by magnetic particle imaging

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

The Applications of Magnetic Particle Imaging: From Cell to Body

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