High-efficiency magnetophoretic labelling of adoptively-transferred T cells for longitudinal Magnetic Particle Imaging.

While adoptive cell therapies (ACT) have been successful as therapies for blood cancers, they have limited efficacy in treating solid tumours, where the tumour microenvironment excludes and suppresses adoptively transferred tumour-specific immune cells. A major obstacle to improving cell therapies for solid tumours is a lack of accessible and quantitative imaging modalities capable of tracking the migration and immune functional activity of ACT products for an extended duration . A high-efficiency magnetophoretic method was developed for facile magnetic labelling of hard-to-label immune cells, which were then injected into tumour-bearing mice and imaged over two weeks with a compact benchtop Magnetic Particle Imager (MPI) design.

Pulsed MPI Relaxometry of Brownian and Néel Field-Dependent Relaxation in Superparamagnetic Magnetite Nanoparticles Confirm Theory and Simulations.

Superparamagnetic iron oxide nanoparticles (SPIOs) are used as tracers in Magnetic Particle Imaging (MPI). It is crucial to understand the magnetic properties of SPIOs for optimizing MPI imaging contrast, resolution, and sensitivity. Brownian and Néel relaxation theory developed in the early 1950s posits that relaxation times can vary with particle size, shell thickness, medium viscosity, and the applied field strength.

Magnetic nanoparticles for magnetic particle imaging (MPI): design and applications.

Recent advancements in medical imaging have brought forth various techniques such as magnetic resonance imaging (MRI), computed tomography (CT), positron emission tomography (PET), and ultrasound, each contributing to improved diagnostic capabilities. Most recently, magnetic particle imaging (MPI) has become a rapidly advancing imaging modality with profound implications for medical diagnostics and therapeutics. By directly detecting the magnetization response of magnetic tracers, MPI surpasses conventional imaging modalities in sensitivity and quantifiability, particularly in stem cell tracking applications.

Superferromagnetic Nanoparticles Enable Order-of-Magnitude Resolution & Sensitivity Gain in Magnetic Particle Imaging.

Magnetic nanoparticles have many advantages in medicine such as their use in non-invasive imaging as a Magnetic Particle Imaging (MPI) tracer or Magnetic Resonance Imaging contrast agent, the ability to be externally shifted or actuated and externally excited to generate heat or release drugs for therapy. Existing nanoparticles have a gentle sigmoidal magnetization response that limits resolution and sensitivity. Here it is shown that superferromagnetic iron oxide nanoparticle chains (SFMIOs) achieve an ideal step-like magnetization response to improve both image resolution & SNR by more than tenfold over conventional MPI.

Magnetic Particle Imaging: An Emerging Modality with Prospects in Diagnosis, Targeting and Therapy of Cancer.

Background: Magnetic Particle Imaging (MPI) is an emerging imaging modality for quantitative direct imaging of superparamagnetic iron oxide nanoparticles (SPION or SPIO). With different physics from MRI, MPI benefits from ideal image contrast with zero background tissue signal. This enables clear visualization of cancer with image characteristics similar to PET or SPECT, but using radiation-free magnetic nanoparticles instead, with infinite-duration reporter persistence in vivo.

Non-radioactive and sensitive tracking of neutrophils towards inflammation using antibody functionalized magnetic particle imaging tracers.

White blood cells (WBCs) are a key component of the mammalian immune system and play an essential role in surveillance, defense, and adaptation against foreign pathogens. Apart from their roles in the active combat of infection and the development of adaptive immunity, immune cells are also involved in tumor development and metastasis. Antibody-based therapeutics have been developed to regulate (i.

Combining magnetic particle imaging and magnetic fluid hyperthermia for localized and image-guided treatment.

Magnetic fluid hyperthermia (MFH) has been widely investigated as a treatment tool for cancer and other diseases. However, focusing traditional MFH to a tumor deep in the body is not feasible because the wavelength of 300 kHz very low frequency (VLF) excitation fields is longer than 100 m. Recently we demonstrated that millimeter-precision localized heating can be achieved by combining magnetic particle imaging (MPI) with MFH.

Using magnetic particle imaging systems to localize and guide magnetic hyperthermia treatment: tracers, hardware, and future medical applications.

Magnetic fluid hyperthermia (MFH) treatment makes use of a suspension of superparamagnetic iron oxide nanoparticles, administered systemically or locally, in combination with an externally applied alternating magnetic field, to ablate target tissue by generating heat through a process called induction. The heat generated above the mammalian euthermic temperature of 37°C induces apoptotic cell death and/or enhances the susceptibility of the target tissue to other therapies such as radiation and chemotherapy. While most hyperthermia techniques currently in development are targeted towards cancer treatment, hyperthermia is also used to treat restenosis, to remove plaques, to ablate nerves and to alleviate pain by increasing regional blood flow.

A porcine model of heart failure with preserved ejection fraction: magnetic resonance imaging and metabolic energetics.

Aims: A significant proportion of heart failure (HF) patients have HF preserved ejection fraction (HFpEF). The lack of effective treatments for HFpEF remains a critical unmet need. A key obstacle to therapeutic innovation in HFpEF is the paucity of pre-clinical models.

Optimization of Drive Parameters for Resolution, Sensitivity and Safety in Magnetic Particle Imaging.

Magnetic Particle Imaging is an emerging tracer imaging modality with zero background signal and zero ionizing radiation, high contrast and high sensitivity with quantitative images. While there is recent work showing that the low amplitude or low frequency drive parameters can improve MPI's spatial resolution by mitigating relaxation losses, the concomitant decrease of the MPI's tracer sensitivity due to the lower drive slew rates was not fully addressed. There has yet to be a wide parameter space, multi-objective optimization of MPI drive parameters for high resolution, high sensitivity and safety.

Pulsed Excitation in Magnetic Particle Imaging.

Magnetic particle imaging (MPI) is a promising new tracer-based imaging modality. The steady-state, nonlinear magnetization physics most fundamental to MPI typically predicts improving resolution with increasing tracer magnetic core size. For larger tracers, and given typical excitation slew rates, this steady-state prediction is compromised by dynamic processes that induce a significant secondary blur and prevent us from achieving high resolution using larger tracers.

In vivo tracking and quantification of inhaled aerosol using magnetic particle imaging towards inhaled therapeutic monitoring.

Pulmonary delivery of therapeutics is attractive due to rapid absorption and non-invasiveness but it is challenging to monitor and quantify the delivered aerosol or powder. Currently, single-photon emission computed tomography (SPECT) is used but requires inhalation of radioactive labels that typically have to be synthesized and attached by hot chemistry techniques just prior to every scan. In this work, we demonstrate that superparamagnetic iron oxide nanoparticles (SPIONs) can be used to label and track aerosols with high sensitivity using an emerging medical imaging technique known as magnetic particle imaging (MPI).

A perspective on a rapid and radiation-free tracer imaging modality, magnetic particle imaging, with promise for clinical translation.

Magnetic particle imaging (MPI), introduced at the beginning of the twenty-first century, is emerging as a promising diagnostic tool in addition to the current repertoire of medical imaging modalities. Using superparamagnetic iron oxide nanoparticles (SPIOs), that are available for clinical use, MPI produces high contrast and highly sensitive tomographic images with absolute quantitation, no tissue attenuation at-depth, and there are no view limitations. The MPI signal is governed by the Brownian and Néel relaxation behavior of the particles.

Magnetic particle imaging for radiation-free, sensitive and high-contrast vascular imaging and cell tracking.

Magnetic particle imaging (MPI) is an emerging ionizing radiation-free biomedical tracer imaging technique that directly images the intense magnetization of superparamagnetic iron oxide nanoparticles (SPIOs). MPI offers ideal image contrast because MPI shows zero signal from background tissues. Moreover, there is zero attenuation of the signal with depth in tissue, allowing for imaging deep inside the body quantitatively at any location.

Magnetic Particle Imaging-Guided Heating in Vivo Using Gradient Fields for Arbitrary Localization of Magnetic Hyperthermia Therapy.

Image-guided treatment of cancer enables physicians to localize and treat tumors with great precision. Here, we present in vivo results showing that an emerging imaging modality, magnetic particle imaging (MPI), can be combined with magnetic hyperthermia into an image-guided theranostic platform. MPI is a noninvasive 3D tomographic imaging method with high sensitivity and contrast, zero ionizing radiation, and is linearly quantitative at any depth with no view limitations.

The Relaxation Wall: Experimental Limits to Improving MPI Spatial Resolution by Increasing Nanoparticle Core size.

Magnetic Particle Imaging (MPI) is a promising new tracer modality with zero attenuation in tissue, high contrast and sensitivity, and an excellent safety profile. However, the spatial resolution of MPI is currently around 1 mm in small animal scanners. Especially considering tradeoffs when scaling up MPI scanning systems to human size, this resolution needs to be improved for clinical applications such as angiography and brain perfusion.

Magnetic Particle Imaging for Highly Sensitive, Quantitative, and Safe in Vivo Gut Bleed Detection in a Murine Model.

Gastrointestinal (GI) bleeding causes more than 300 000 hospitalizations per year in the United States. Imaging plays a crucial role in accurately locating the source of the bleed for timely intervention. Magnetic particle imaging (MPI) is an emerging clinically translatable imaging modality that images superparamagnetic iron-oxide (SPIO) tracers with extraordinary contrast and sensitivity.

Seeing SPIOs Directly In Vivo with Magnetic Particle Imaging.

Magnetic particle imaging (MPI) is a new molecular imaging technique that directly images superparamagnetic tracers with high image contrast and sensitivity approaching nuclear medicine techniques-but without ionizing radiation. Since its inception, the MPI research field has quickly progressed in imaging theory, hardware, tracer design, and biomedical applications. Here, we describe the history and field of MPI, outline pressing challenges to MPI technology and clinical translation, highlight unique applications in MPI, and describe the role of the WMIS MPI Interest Group in collaboratively advancing MPI as a molecular imaging technique.

Combining magnetic particle imaging and magnetic fluid hyperthermia in a theranostic platform.

Magnetic particle imaging (MPI) is a rapidly developing molecular and cellular imaging modality. Magnetic fluid hyperthermia (MFH) is a promising therapeutic approach where magnetic nanoparticles are used as a conduit for targeted energy deposition, such as in hyperthermia induction and drug delivery. The physics germane to and exploited by MPI and MFH are similar, and the same particles can be used effectively for both.

A High-Throughput, Arbitrary-Waveform, MPI Spectrometer and Relaxometer for Comprehensive Magnetic Particle Optimization and Characterization.

Magnetic Particle Imaging (MPI) is a promising new tracer modality with zero attenuation deep in tissue, high contrast and sensitivity, and an excellent safety profile. However, the spatial resolution of MPI is limited to around 1 mm currently and urgently needs to be improved for clinical applications such as angiography and brain perfusion. Although MPI resolution is highly dependent on tracer characteristics and the drive waveforms, optimization is limited to a small subset of possible excitation strategies by current MPI hardware that only does sinusoidal drive waveforms at very few frequencies.