Complex Relationship Between Signal Intensity Properties in Magnetic Particle Imaging (MPI) and Iron Oxide Nanoparticle Degradation

Magnetic particle imaging (MPI) is an exciting new biomedical imaging technology that uses superparamagnetic nanoparticles as an imaging tracer. MPI is touted as a quantitative imaging modality but MPI signal properties have never been characterized for nanoparticles undergoing biodegradation. Here we characterize the nature of the MPI signal properties as a function of degradation of various magnetic particle formulations. We show that MPI signal properties can increase or decrease as a function of nanoparticle formulation and chemical environment and that long-term in vitro experiments only roughly approximate long-term in vivo MPI signal properties. Data are supported by electron microscopy of nanoparticle degradation. Knowledge of MPI signal property changes during nanoparticle degradation will be critical in design and interpretation of all MPI experiments. Further, we demonstrate for the first time, an environmentally sensitive MPI contrast mechanism opening the door to smart contrast paradigms in MPI.<br>

Complex Relationship Between Signal Intensity Properties in Magnetic Particle Imaging (MPI) and Iron Oxide Nanoparticle Degradation

10.26434/chemrxiv.11845584 ◽

2020 ◽

Author(s):

Julia Guzy ◽

Shatadru Chakravarty ◽

Foster Buchanan ◽

Haoran Chen ◽

Jeffrey M. Gaudet ◽

...

Keyword(s):

Magnetic Particle ◽

Imaging Modality ◽

Quantitative Imaging ◽

Superparamagnetic Nanoparticles ◽

Iron Oxide Nanoparticle ◽

Magnetic particle imaging (MPI) is an exciting new biomedical imaging technology that uses superparamagnetic nanoparticles as an imaging tracer. MPI is touted as a quantitative imaging modality but MPI signal properties have never been characterized for nanoparticles undergoing biodegradation. Here we characterize the nature of the MPI signal properties as a function of degradation of various magnetic particle formulations. We show that MPI signal properties can increase or decrease as a function of nanoparticle formulation and chemical environment and that long-term in vitro experiments only roughly approximate long-term in vivo MPI signal properties. Data are supported by electron microscopy of nanoparticle degradation. Knowledge of MPI signal property changes during nanoparticle degradation will be critical in design and interpretation of all MPI experiments. Further, we demonstrate for the first time, an environmentally sensitive MPI contrast mechanism opening the door to smart contrast paradigms in MPI.<br>

Development of Magnetic Particle Imaging (MPI) for Cell Tracking and Detection

10.1101/2020.07.12.197780 ◽

2020 ◽

Author(s):

Kierstin P Melo ◽

Ashley V Makela ◽

Natasha N Knier ◽

Amanda M Hamilton ◽

Paula J Foster

Keyword(s):

Iron Content ◽

Cell Tracking ◽

Magnetic Particle ◽

Ex Vivo ◽

Imaging Modality ◽

Superparamagnetic Iron Oxide ◽

Cell Injection ◽

AbstractIntroductionMagnetic particle imaging (MPI) is a new imaging modality that sensitively and specifically detects superparamagnetic iron oxide nanoparticles (SPIONs) within a sample. SPION-based MRI cell tracking has very high sensitivity, but low specificity and quantification of iron labeled cells is difficult. MPI cell tracking could overcome these challenges.MethodsMDM-AB-231BR cells labeled with MPIO, mice were intracardially injected with either 2.5 × 105 or 5.0 × 105 cells. MRI was performed in vivo the same day at 3T using a bSSFP sequence. After mice were imaged ex vivo with MPI. In a second experiment Mice received an intracardiac injection of either 2.5 × 10 5 or 5 × 10 4 MPIO-labeled 231BR cells. In a third experiment, mice were injected with 5 × 10 4 4T1BR cells, labelled with either MPIO or the SPION Vivotrax. MRI and MPI was performed in vivo.ResultsSignal from MPI and signal voids from MRI both showed more iron content in mice receiving an injection of 5.0 × 105 cells than the 2.5 × 105 injection. In the second experiment, Day 0 MRI showed signal voids and MPI signal was detected in all mouse brains. The MPI signal and iron content measured in the brains of mice that were injected with 2.5 × 10 5 cells were approximately four times greater than in brains injected with 5 × 10 4 cells. In the third experiment, in vivo MRI was able to detect signal voids in the brains of mice injected with Vivotrax and MPIO, although voids were fainter in Vivotrax labeled cells. In vivo MPI signal was only detectable in mice injected with MPIO-labeled cells.ConclusionThis is the first example of the use of MPIO for cell tracking with MPI. With an intracardiac cell injection, approximately 15% of the injected cells are expected to arrest in the brain vasculature. For our lowest cell injection of 5.0 × 104 cells this is ∼10000 cells.

Magnetic Particle Imaging tracks the long-term fate of in vivo neural cell implants with high image contrast

Scientific Reports ◽

10.1038/srep14055 ◽

2015 ◽

Vol 5 (1) ◽

Cited By ~ 103

Author(s):

Bo Zheng ◽

Tandis Vazin ◽

Patrick W. Goodwill ◽

Anthony Conway ◽

Aradhana Verma ◽

...

Keyword(s):

Magnetic Particle ◽

Neural Cell ◽

Image Contrast ◽

Magnetic Particle Imaging is a sensitive in vivo imaging modality for the quantification of dendritic cell migration

10.1101/2021.09.22.461401 ◽

2021 ◽

Author(s):

Julia J Gevaert ◽

Corby Fink ◽

Jimmy D. Dikeakos ◽

Gregory A. Dekaban ◽

Paula J Foster

Keyword(s):

Dendritic Cell ◽

Lymph Nodes ◽

In Vivo Imaging ◽

Magnetic Particle ◽

Ex Vivo ◽

Imaging Modality ◽

Cellular Mri ◽

Immunotherapies, such as dendritic cell- (DC-)based therapies, are useful for treating cancer as an alternative to or in combination with traditional therapies. Cells must migrate to lymphoid organs to be effective and the magnitude of the ensuing T cell response is proportional to the number of lymph node-migrated DC. With less than 10% of cells expected to reach their destination, there is a need for an imaging modality capable of sensitively and quantitatively detecting cells. MRI has been used to track DC using iron and 19F methods, with limitations. Quantification of iron-induced signal loss is indirect and challenging; 19F signal is directly quantifiable but lacks sensitivity. Magnetic Particle Imaging (MPI) directly detects superparamagnetic iron oxide nanoparticles (SPIO) and enables quantitation of low numbers of SPIO-labeled cells. Here we describe the first study using MPI to track and quantify the migration of DC, injected into the footpads of C57BL/6 mice, to the popliteal lymph nodes (pLNs). As DC migrate from the site of injection to the lymph nodes, we measured a decrease in signal in the footpads and an increase in signal at the pLNs. The presence of SPIO-labeled DC in nodes was validated by ex vivo MPI and histology. By measuring the iron mass per cell in samples of labeled cells, we were able to provide an estimate of cell number for each source of signal and we report a sensitivity of approximately 4000 cells in vivo and 2000 cells ex vivo. For some mice, MPI was compared to cellular MRI. We also bring attention to the issue of resolving unequal signals within close proximity, a challenge for many pre-clinical studies using a highly concentrated tracer bolus that over shadows nearby lower signals. This study demonstrates the clear advantage of MPI to detect and quantify cells in vivo, bridging the gap left by cellular MRI, and all other in vivo imaging modalities, and opening the door for quantitative imaging of cellular immunotherapies.

Magnetic particle imaging: tracer development and the biomedical applications of a radiation-free, sensitive, and quantitative imaging modality

Nanoscale ◽

10.1039/d1nr05670k ◽

2022 ◽

Author(s):

Stanley Harvell-Smith ◽

Le Duc Tung ◽

Nguyen Thi Kim Thanh

Keyword(s):

Biomedical Applications ◽

Magnetic Particle ◽

Imaging Modality ◽

Quantitative Imaging ◽

Three Dimensional ◽

Superparamagnetic Iron Oxide ◽

Oxide Nanoparticles ◽

Particle Imaging ◽

Tracer Development

Magnetic particle imaging (MPI) is an emerging tracer-based modality that enables real-time three-dimensional imaging of the non-linear magnetisation produced by superparamagnetic iron oxide nanoparticles (SPIONs), in the presence of an...

Magnetic particle imaging of particle dynamics in complex matrix systems

Physical Sciences Reviews ◽

10.1515/psr-2019-0123 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Sebastian Draack ◽

Meinhard Schilling ◽

Thilo Viereck

Keyword(s):

Magnetic Particle ◽

Imaging Modality ◽

Three Dimensional ◽

Local Environment ◽

Relaxation Mechanism ◽

Harmonic Spectrum ◽

Matrix Interactions ◽

Tracer Distribution ◽

Abstract Magnetic particle imaging (MPI) is a young imaging modality for biomedical applications. It uses magnetic nanoparticles as a tracer material to produce three-dimensional images of the spatial tracer distribution in the field-of-view. Since the tracer magnetization dynamics are tied to the hydrodynamic mobility via the Brownian relaxation mechanism, MPI is also capable of mapping the local environment during the imaging process. Since the influence of viscosity or temperature on the harmonic spectrum is very complicated, we used magnetic particle spectroscopy (MPS) as an integral measurement technique to investigate the relationships. We studied MPS spectra as function of both viscosity and temperature on model particle systems. With multispectral MPS, we also developed an empirical tool for treating more complex scenarios via a calibration approach. We demonstrate that MPS/MPI are powerful methods for studying particle-matrix interactions in complex media.

Introducing a frequency-tunable magnetic particle spectrometer

Current Directions in Biomedical Engineering ◽

10.1515/cdbme-2015-0062 ◽

2015 ◽

Vol 1 (1) ◽

pp. 249-253 ◽

Cited By ~ 2

Author(s):

André Behrends ◽

Matthias Graeser ◽

Thorsten M. Buzug

Keyword(s):

Magnetic Nanoparticles ◽

Image Quality ◽

Magnetic Particle ◽

Imaging Modality ◽

Common Technique ◽

Frequency Tunable ◽

Excitation Frequencies ◽

AbstractImage quality in the new imaging modality magnetic particle imaging (MPI) heavily relies on the quality of the magnetic nanoparticles in use. Therefore, it is crucial to understand the behaviour of such particles. A common technique to analyze the behaviour of the particles is magnetic particle spectrometry (MPS). However, most spectrometers are limited to measurements at a single or multiple discrete excitation frequencies. This paper introduces a frequency-tunable spectrometer, able to perform measurements in the range of 100 Hz - 24kHz.

In vivo magnetic particle imaging: angiography of inferior vena cava and aorta in rats using newly developed multicore particles

Scientific Reports ◽

10.1038/s41598-020-74151-4 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Azadeh Mohtashamdolatshahi ◽

Harald Kratz ◽

Olaf Kosch ◽

Ralf Hauptmann ◽

Nicola Stolzenburg ◽

...

Keyword(s):

Image Quality ◽

Inferior Vena Cava ◽

Temporal Resolution ◽

Magnetic Particle ◽

Inferior Vena ◽

Vena Cava ◽

High Temporal Resolution ◽

Abstract Magnetic Particle Imaging (MPI) is a new imaging modality, which maps the distribution of magnetic nanoparticles (MNP) in 3D with high temporal resolution. It thus may be suited for cardiovascular imaging. Its sensitivity and spatial resolution critically depend on the magnetic properties of MNP. Therefore, we used novel multicore nanoparticles (MCP 3) for in-vivo MPI in rats and analyzed dose requirements, sensitivity and detail resolution. 8 rats were examined using a preclinical MPI scanner (Bruker Biospin GmbH, Germany) equipped with a separate receive coil. MCP 3 and Resovist were administered intravenously (i.v.) into the rats’ tail veins at doses of 0.1, 0.05 and 0.025 mmol Fe/kg followed by serial MPI acquisition with a temporal resolution of 46 volumes per second. Based on a qualitative visual scoring system MCP 3–MPI images showed a significantly (P ≤ 0.05) higher image quality than Resovist-MPI images. Morphological features such as vessel lumen diameters (DL) of the inferior vena cava (IVC) and abdominal aorta (AA) could be assessed along a 2-cm segment in mesenteric area only after administration of MCP 3 at dosages of 0.1, 0.05 mmol Fe/kg. The mean DL ± SD estimated was 2.7 ± 0.6 mm for IVC and 2.4 ± 0.7 mm for AA. Evaluation of DL of the IVC and AA was not possible in Resovist-MPI images. Our results show, that MCP 3 provide better image quality at a lower dosage than Resovist. MCP 3-MPI with a clinically acceptable dose of 0.05 mmol Fe/kg increased the visibility of vessel lumens compared to Resovist-based MPI towards possible detection of vascular abnormalities such as stenosis or aneurysms, in vivo.

Applications of PDEs inpainting to magnetic particle imaging and corneal topography

Opuscula Mathematica ◽

10.7494/opmath.2019.39.4.453 ◽

2019 ◽

Vol 39 (4) ◽

pp. 453-482 ◽

Cited By ~ 1

Author(s):

Andrea Andrisani ◽

Rosa Maria Mininni ◽

Francesca Mazzia ◽

Giuseppina Settanni ◽

Alessandro Iurino ◽

...

Keyword(s):

Fourth Order ◽

Magnetic Particle ◽

Approximation Error ◽

Medical Application ◽

Superparamagnetic Nanoparticles ◽

Corneal Surface ◽

Radial Curvature ◽

Particle Imaging ◽

Standard Approximation

In this work we propose a novel application of Partial Differential Equations (PDEs) inpainting techniques to two medical contexts. The first one concerning recovering of concentration maps for superparamagnetic nanoparticles, used as tracers in the framework of Magnetic Particle Imaging. The analysis is carried out by two set of simulations, with and without adding a source of noise, to show that the inpainted images preserve the main properties of the original ones. The second medical application is related to recovering data of corneal elevation maps in ophthalmology. A new procedure consisting in applying the PDEs inpainting techniques to the radial curvature image is proposed. The images of the anterior corneal surface are properly recovered to obtain an approximation error of the required precision. We compare inpainting methods based on second, third and fourth-order PDEs with standard approximation and interpolation techniques.