Magnetic Hyperthermia Research Articles

Body Bag Cooling with Two Different Water Temperatures for the Treatment of Hyperthermia.

INTRODUCTION: Exertional heatstroke (EHS) is a life-threatening condition that requires quick recognition and cooling for survival. Experts recommend using cooling modalities that reduce rectal temperature (TREC) faster than 0.16°C/min though rates above 0.08°C/min are considered "acceptable." Hyperthermic individuals treated in body bags filled with ice water (∼3°C) have excellent cooling rates (0.28 ± 0.09°C/min). However, clinicians may not have access to large amounts of ice or ice water when treating EHS victims. The purpose of this study was to determine if using a body bag filled with water near the upper limits of expert recommendations for EHS treatment would produce acceptable (>0.08°C/min) or "ideal (>0.16°C/min)" TREC cooling rates or different nadir values.METHODS: A total of 12 individuals (9 men, 3 women; age: 21 ± 2 yr; mass: 74.6 ± 10.2 kg; height: 179.5 ± 9.6 cm) exercised in the heat until TREC was 39.5°C. They lay supine while 211.4 ± 19.5 L of 10°C (Ten) or 15°C (Fifteen) water was poured into a body bag. Subjects cooled until TREC was 38°C. They exited the body bag and rested in the heat for 10 min.RESULTS: Subjects exercised in similar conditions and for similar durations (Ten = 46.3 ± 8.6 min, Fifteen = 46.2 ± 7.8 min). TREC cooling rates were faster in Ten than Fifteen (Ten = 0.18 ± 0.07°C/min, Fifteen = 0.14 ± 0.09°C/min). TREC nadir was slightly higher in Fifteen (37.3 ± 0.2°C) than Ten (37.1 ± 0.3°C).DISCUSSION: Body bag cooling rates met expert definitions of acceptable (Fifteen) and ideal (Ten) for EHS treatment. This information is valuable for clinicians who do not have access to or the resources for ice water cooling to treat EHS.Miller KC, Amaria NY. Body bag cooling with two different water temperatures for the treatment of hyperthermia. Aerosp Med Hum Perform. 2024; 95(4):194-199.

Concentration dependent thermal properties of magnetic nanoparticles and ability to use in the magnetic hyperthermia treatment

Concentration dependent thermal properties of magnetic nanoparticles and ability to use in the magnetic hyperthermia treatment

Emerging Application of Graphene Quantum Dots in Photodynamic/Photothermal and Hyperthermia Therapies for Cancer Treatment

Emerging Application of Graphene Quantum Dots in Photodynamic/Photothermal and Hyperthermia Therapies for Cancer Treatment

Ferromagnetic and ohmic effects on nanofluid flow via permeability rotative disk: significant interparticle radial and nanoparticle radius

The significance of interparticle spacing and nanoparticle radius for the case of single-phase nanofluid flow has often been neglected. Tremendous applications of this phenomenon can be witnessed in different fields, especially in electron microscopes, heat exchange processes, and many others. This research highlights this vital aspect of Ohmic heating in nanofluid flow over a spinning disk. To ensure the novelty, a ferromagnetic nanoparticle (Manganese ferrite) has been incorporated to examine interparticle spacing and particle radius to explore the features of heat transfer. The ferromagnetic nanofluids are vital in carriers for drug delivery systems, in cancer treatment, design of systems for hyperthermia therapy, in microfluidic devices used for chemical synthesis, etc. The quantiles of dimensional equations are converted into dimensionless ones by adopting similarity transformations and to solve highly coupled nonlinear equations numerically, built-in bvp5c MATLAB tool is utilized. The effect of a few revealed factors, the velocity and temperature distributions, are examined via visualization. Furthermore, streamlined plots are also visualized. The outcomes produced showed excellent agreement with those made in the literature in the same direction by assuming some exceptional cases on different gradients. Further, the outstanding results are reported as; the permeability of the surface produces the suction velocity, and the enhanced suction velocity attenuates the fluid velocity in either of the case of pure and nanofluid. The increase in thermal radiation boosts up the heat transfer rate whereas the augmentation in the Eckert number retards it significantly.

The role of biocompatible coatings of magnetic nanorods on their thermal response in hyperthermia. Consequences on tumor cell survival

There are so many hopes for nanoscience as a tool in the fight against various diseases, notably cancer, that the problem can be approached from many different points of view. In this paper, we focus on two essential aspects. One is the preparation of non-spherical and superparamagnetic magnetic particles, with the right size to be able to exit the blood vessels and be incorporated by cells. The second is their use as agents of hyperthermia. For the first purpose, a two-step method was followed, in which hematite templates with the desired shape and size were first prepared, and these were subsequently reduced by heat treatment. As a result, nanorods with a length of 40 nm and an axis ratio of 1:8 were obtained. The bare particles were coated with a triple layer of cationic/anionic/cationic polymers. Electrophoretic mobility, thermogravimetric analysis, x-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy evaluations confirmed the presence of the coating and the positive charge of the last polymeric layer, while x-ray diffraction and micro-Raman spectroscopy indicated that the crystal structure of the core particles was magnetite/maghemite. The magnetization cycles of the particles showed that they were superparamagnetic, with a saturation magnetization of 82 emu/g in the case of the bare particles. For concentrations up to 300 μg/mL, they were found to be compatible with MCF7 (Michigan Cancer Foundation-7) breast cancer cell line, for cell uptakes higher than 80 %. Both bare and polymer-coated particles produced heating by magnetic hyperthermia and laser-light irradiation. Finally, cytotoxicity against the cancer cells was evaluated, and it was found that photothermia and, above all, magnetic hyperthermia applied to the coated particles could induce more than 50% cell death.

Fabrication of a magnetic nanocomposite based on natural hydrogel: Pectin, tragacanth gum, silk fibroin, and integrated graphitic carbon nitride for hyperthermia and biological features

The current study aimed to design and synthesize a new magnetic nanobiocomposite and assess its potential for biological applications and hyperthermia. For this purpose, in the first step, the Pectin (PC) and Tragacanth gum (TG) polymer was synthesized using CaCl2 as a cross-linking agent (PC-TG hydrogel). In the second step, natural Silk fibroin (SF) protein and graphitic carbon nitride (CN) were added to the hydrogel to upgrade the nanobiocomposite's strength and due to CN's pharmacology applications, respectively. Finally, for an enhanced hyperthermia application, PC-TG hydrogel/SF/CN was in situ magnetized with Fe3O4 magnetic nanoparticles (MNPs), and PC-TG hydrogel/SF/CN/Fe3O4 nanobiocomposite was synthesized. By using a vibrating-sample magnetometer (VSM), Fourier-transformed infrared (FTIR), thermogravimetric analysis (TGA), energy dispersive X-ray (EDX), X-ray diffraction (XRD), and field-emission scanning electron microscope (FESEM), the structural features and properties of the PC-TG hydrogel/SF/CN/Fe3O4 nanobiocomposite were determined. This magnetic nanobiocomposite's saturation magnetization value was 14.84 emu g-1. The hemolytic assay of this new nanobiocomposite demonstrated that the hemolysis percentage was 1.07 %, around 99.0 % of cells were able to survive, and the MTT assay was used to assess the anticancer activity against breast cancer cell lines (BT549). Additionally, 62.51 (W g-1) in 200.0 kHz was found to be the greatest specific absorption rate (SAR). These findings suggest that the recently created magnetic nanobiocomposite might function admirably in hyperthermia treatment when exposed to an alternating magnetic field.

Analysis of activation energy on the Johnson–Segalman nanofluid through an asymmetric microchannel: Numerical study

Activation energy and thermal radiation as a means of heat transfer are significant and fascinating phenomena for scientists and researchers because of their significance in cancer treatment. As a result, heat kills cancer cells and shrinks tumors, making hyperthermia therapy a cutting-edge cancer treatment. This paper examines the peristaltic motion of a Johnson–Segalman nanofluid across an asymmetric pliable microchannel under the impact of activation energy. We obtained the governing equations for the non-Newtonian nanofluid. Partial differential equations (PDEs) are reduced to ordinary differential equations (ODEs) under the assumption of large wavelengths and tiny Reynolds number assumptions. The flow patterns and trapping phenomena were numerically generated using the NDSolve command of the computational mathematical software Mathematica. The influence of important liquid parameters was examined with graphical representations of the results. The current study reveals an enhancement in the heat generation parameter, an enhancement in the temperature and a reduction in the concentration.

Heating efficiency of agarose samples doped with magnetic nanoparticles subjected to ultrasonic and magnetic field

Recently, magneto-ultrasound heating of tissue in the presence of magnetic nanoparticles (NPs) has been studied due to its high potential for use in oncological hyperthermia. It has been published that a synergistic effect, generation of additional heat caused by magneto-ultrasonic coupling, was observed in a tissue-mimicking material (TMM) enriched with magnetic NPs. The specific absorption rate (SAR) was determined from the temperature rise measurements in a focus of the ultrasound beam. It is important to use precise measurement methods when considering medical applications, for which there are limitations to the power of each field, resulting from the prevention of biological phenomena dangerous to the patient. This study demonstrates that in magneto-ultrasonic heating SAR can be measured much more accurately if the ultrasonic field is almost uniform. Measurements were performed on TMM containing Fe3O4 NPs with a diameter of approximately 8 nm and superparamagnetic properties. Both, the measurement and simulation results showed that the errors resulting from the inaccuracy of placing the temperature probe are smaller than in the case of the focused ultrasound. At the same time, the temperature increase caused by the ultrasonic field is almost linear and the influence of heat convection on the SAR determination is negligible. The measurements showed that magneto-ultrasonic hyperthermia can provide the desired thermal effect at lower ultrasound powers and magnetic fields compared to ultrasonic or magnetic hyperthermia used alone. No synergy effect was recorded.

Enhancement of skin tumor laser hyperthermia with Ytterbium nanoparticles: numerical simulation

Laser hyperthermia therapy (HT) has emerged as a well-established method for treating cancer, yet it poses unique challenges in comprehending heat transfer dynamics within both healthy and cancerous tissues due to their intricate nature. This study investigates laser HT therapy as a promising avenue for addressing skin cancer. Employing two distinct near-infrared (NIR) laser beams at 980 nm, we analyze temperature variations within tumors, employing Pennes’ bioheat transfer equation as our fundamental investigative framework. Furthermore, our study delves into the influence of Ytterbium nanoparticles (YbNPs) on predicting temperature distributions in healthy and cancerous skin tissues. Our findings reveal that the application of YbNPs using a Gaussian beam shape results in a notable maximum temperature increase of 5 °C within the tumor compared to nanoparticle-free heating. Similarly, utilizing a flat top beam alongside YbNPs induces a temperature rise of 3 °C. While this research provides valuable insights into utilizing YbNPs with a Gaussian laser beam configuration for skin cancer treatment, a more thorough understanding could be attained through additional details on experimental parameters such as setup, exposure duration, and specific implications for skin cancer therapy.

Analysis of risk factors for major post-operative complications following intraperitoneal hyperthermic perfusion for pseudomyxoma peritonei: A retrospective cohort study.

Pseudomyxoma peritonei (PMP) is a condition characterised by the presence of gelatinous tumour-like growth within the peritoneal cavity. Combined cytoreductive surgery and intraperitoneal chemotherapy have shown to improve the survival rate in PMP patients. However, post-operative complications such as cognitive dysfunction, respiratory insufficiency and acute renal failure are still observed. This retrospective study aims to explore the risk factors associated with major post-operative complications and specifically investigate the correlation with intraoperative hypotension. This retrospective cohort study included PMP patients treated at Beijing Aerospace Center Hospital from 1 June, 2014 to 30 December, 2020. The primary outcome measures were major post-operative complications, including neurological, pulmonary, cardiovascular, surgical complications, acute hepatic injury and acute kidney injuries. The secondary outcome measures included infection, fever and deep venous thrombosis. Statistical analysis was conducted using EmpowerStats and R software. A total of 782 patients were screened, and 668 patients were included in the statistical analysis. Amongst them, 234 (35.03%) individuals experienced major post-operative complications. Factors such as pre-operative American Society of Anaesthesiologists grading, age, haemoglobin and albumin levels, intraoperative mean arterial pressure, blood loss, fluid replacement volume, method of intraperitoneal hyperthermic perfusion and post-operative requirement for intensive care unit mechanical ventilation were found to be correlated with major complications. The identified risk factors provide valuable insights for improving clinical pathways in the management of PMP. Further prospective studies are warranted to establish the association between these factors and patient outcomes.

Nanodiamonds: A Cutting-Edge Approach to Enhancing Biomedical Therapies and Diagnostics in Biosensing.

Nanodiamonds (NDs) have garnered attention in the field of nanomedicine due to their unique properties. This review offers a comprehensive overview of NDs synthesis methods, properties, and their uses in biomedical applications. Various synthesis techniques, such as detonation, high-pressure, high-temperature, and chemical vapor deposition, offer distinct advantages in tailoring NDs' size, shape, and surface properties. Surface modification methods further enhance NDs' biocompatibility and enable the attachment of bioactive molecules, expanding their applicability in biological systems. NDs serve as promising nanocarriers for drug delivery, showcasing biocompatibility and the ability to encapsulate therapeutic agents for targeted delivery. Additionally, NDs demonstrate potential in cancer treatment through hyperthermic therapy and vaccine enhancement for improved immune responses. Functionalization of NDs facilitates their utilization in biosensors for sensitive biomolecule detection, aiding in precise diagnostics and rapid detection of infectious diseases. This review underscores the multifaceted role of NDs in advancing biomedical applications. By synthesizing NDs through various methods and modifying their surfaces, researchers can tailor their properties for specific biomedical needs. The ability of NDs to serve as efficient drug delivery vehicles holds promise for targeted therapy, while their applications in hyperthermic therapy and vaccine enhancement offer innovative approaches to cancer treatment and immunization. Furthermore, the integration of NDs into biosensors enhances diagnostic capabilities, enabling rapid and sensitive detection of biomolecules and infectious diseases. Overall, the diverse functionalities of NDs underscore their potential as valuable tools in nanomedicine, paving the way for advancements in healthcare and biotechnology.

Solvothermally synthesized magnetite nanorods for application in magnetic hyperthermia and photothermia

The development of the multi-functional nanostructures has recently been of particular interest in therapeutic research for various diseases including atherosclerosis, cancer, etc. Indeed, the use of multi-responsive nanostructures that can remotely be activated by different stimuli is a promising strategy to combine the advantages of standalone methods and overcome their intrinsic drawbacks. In this regard, thermal treatment using heat-generating magnetic nanostructures that can remotely respond to a wide range of electromagnetic stimuli is of especial importance, mainly applied through magnetic hyperthermia therapy (MHT) and photothermal therapy (PTT) modalities. In this work, magnetite (Fe3O4) nanorods (MNRs) were synthesized using a one-pot solvothermal process. Adjusting the amount of hexadecylamine capping ligand and the filling percentage of the autoclave, uniformed-sized MNRs of 4·46nm in diameter and 31·09nm in length were prepared and investigated in terms of their heat-generating ability for application in the MHT and PTT. The experimental results show the good heat-generating ability of the MNRs in both modalities with the maximum absorption rate (SAR) values of 228.51 W/g (MHT) and 56.59 W/g (PTT).

Abstract 5747: Microwave responsive thermosensitive lipid nanoparticles for spatiotemporal delivery of chemotherapeutics

Abstract Pancreatic cancer is a highly lethal malignancy with an urge for the exploration of novel treatments. One promising approach is microwaved-induced hyperthermia, which has shown great antitumor and synergistic effects when combined with other therapies. The application of microwaves produces heat by dielectric hysteresis which depends on the dielectric properties of molecules. Ionic liquids (ILs) are compounds composed of ions with <100 °C melting point and have strong dielectric properties. In short, we propose the creation of microwave-sensitive nanoparticles using IL, enabling precise hyperthermia induction with low-powered microwaves in localized areas. To achieve this, we stabilize a core composed of 1-butyl-methylimidazolium bromide or 1-butyl-3-methylimidazolium hexafluorophosphate using Span 80, Tween 20, and Triton-X as surfactants, along with phosphatidylcholine lipids as “cosurfactants”. Employing a double emulsion procedure for fabrication, nanoparticles are characterized using dynamic light scattering, Fourier-transform infrared spectroscopy, and transmission electron microscopy. Furthermore, we assess microwave sensitivity by comparing thermal changes between liposomes loaded with 120 mM and 250 mM NaCl solutions. Subsequently, we evaluate biocompatibility and heat effects by incubating IL nanoparticles with BXPC3 and KPC cells, monitoring cell viability through MTT assays. We aim to confine the ILs within the nanoparticle core rather than incorporating them into the membrane. We anticipate increased microwave sensitivity, translating to reduced off-target effects and enhanced precision in hyperthermia treatment. This research holds promise for improving the therapeutic outcomes of pancreatic cancer treatment. Citation Format: Cesar B. Aparicio-Lopez. Microwave responsive thermosensitive lipid nanoparticles for spatiotemporal delivery of chemotherapeutics [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5747.

Abstract 5695: miR-5787 suppresses cancer cell growth as a Fe3O4-nanoparticles induced pivotal miRNA

Abstract Nanotechnology offers great potential for cancer diagnosis and treatments. Especially, nanoparticles (NPs) have been examined and utilized as drug delivery systems, hyperthermia and combination therapy. We have examined and reported the combined effects of Fe3O4-nanoparticles (Fe3O4-NPs) with chemotherapeutic agents on prostate cancer cell in vitro. miRNAs are an important factor in cancer progression, and elucidating the miRNA-mediated intracellular network of cancer cells could suggest new cancer treatment strategies. In this study, to identify microRNAs (miRNAs) associated with anticancer effects of Fe3O4-NPs, the comprehensive expression of miRNAs by Microarray (Agilent G4780A SuperPrint G3 Human v16 miRNA 8x60K Microarray kit) in A549 (lung cancer cell line), LNCaP (androgen-dependent prostate cancer cell line) and DU145 (androgen-independent prostate cancer cell line) under Fe3O4-NPs exposure was performed. miR-5787 was one of the increased miRNAs in three cancer cell lines under Fe3O4-NPs, and its increase in miR-5787 was due to the reactive oxygen species (ROS) production by Fe3O4-NPs. The additional analysis suggested that miR-5787 might suppressed the cancer cell growth by targeting the eIF5. In this study, we identified miR5787 as a Fe3O4-NPs induced pivotal miRNA in cancer cells, and can be used as a therapeutic target. Citation Format: Masatoshi Watanabe, Hitoshi Nakano, Chise Matsuda, Eri Usugi, Hiroshi Imai, Yoshifumi Hirokawa, Kazutoshi Iijima. miR-5787 suppresses cancer cell growth as a Fe3O4-nanoparticles induced pivotal miRNA [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5695.

Human head sized magnetorelaxometry imaging of magnetic nanoparticles with optically pumped magnetometers — A feasibility study

Magnetic nanoparticles (MNP) offer exciting biomedical applications, e.g. magnetic hyperthermia for tumor treatment. The knowledge of the quantitative spatial distribution of MNP in the human body is a key for treatment safety and efficiency. Here we experimentally demonstrate the reconstruction of the quantitative MNP distribution of a human head phantom by magnetorelaxometry imaging (MRXI). The MRXI setup is composed of a 50 channel optically pumped magnetometer (OPM) system and 72 excitation coils, which are operated inside a magnetically shielded room. With our setup, we were able to reconstruct a glioblastoma phantom with a clinically relevant iron amount. A simulation study reveals, that currently the main limitations in terms of reconstruction quality arise from geometrical uncertainties of the setup. Summing up, we demonstrate the feasibility of OPM-MRXI for large regions of interest, potentially advancing the monitoring of MNP in related treatments.

Ti2C3 MXene-based nanocomposite as an intelligent nanoplatform for efficient mild hyperthermia treatment

Photothermal therapy (PTT) has attracted much attention due to its less invasive, controllable and highly effective nature. However, PTT also suffers from intrinsic cancer resistance mediated by cell survival pathways. These survival pathways are regulated by a variety of proteins, among which heat shock protein (HSP) triggers thermotolerance and protects tumor cells from hyperthermia-induced apoptosis. Confronted by this challenge, we propose and validate here a novel MXene-based HSP-inhibited mild photothermal platform, which significantly enhances the sensitivity of tumor cells to heat-induced stress and thus improves the PPT efficacy. The Ti3C2@Qu nanocomposites are constructed by utilizing the high photothermal conversion ability of Ti3C2 nanosheets in combination with quercetin (Qu) as an inhibitor of HSP70. Qu molecules are loaded onto the nanoplatform in a pH-sensitive controlled release manner. The acidic environment of the tumor causes the burst-release of Qu molecules, which deplete the level of heat shock protein 70 (HSP70) in tumor cells and leave the tumor cells out from the protection of the heat-resistant survival pathway in advance, thus sensitizing the hyperthermia efficacy. The nanostructure, photothermal properties, pH-responsive controlled release, synergistic photothermal ablation of tumor cells in vitro and in vivo, and hyperthermia effect on subcellular structures of the Ti3C2@Qu nanocomposites were systematically investigated.

Effect of Gd3+ ion doping on structural, optical, magnetic and dielectric properties on superparamagnetic Mg0.5Zn0.5Fe2−xGdxO4 (0 ≤ x ≤ 1) nanoparticles synthesized via oleic acid assisted chemical co-precipitation method

In the present study, different compositions having general formula Mg0.5Zn0.5GdxFe2−xO4, (x = 0, 0.025, 0.050, 0.075, 0.1) were synthesized using chemical co-precipitation method. The substitution of Gd3+ ions have exhibited profound impacts on the structural, morphological, magnetic, and optical parameters of Mg-Zn ferrites. Single-phase cubic spinel structure has been substantiated by X-ray diffractometer (X-ray diffraction, XRD) analysis for all compositions without any contamination peak. The values of the lattice constant and X-ray density both show an increasing trend when the Gd3+ ion concentration increases. (Fourier transformed infrared spectroscopy) FTIR spectra recorded in the mid-infrared region (4000–400 cm−1) exhibit two main absorption bands associated with the Oh and Td sites within the frequency range of 400–600 cm−1. Morphological studies using (High-resolution transmission electron microscopy) HR-TEM analysis reveal agglomeration of nanoparticles and the average particle size lies between 8 and 9 nm. Maximum magnetization displays an erratic trend with increasing Gd3+ ion concentration, although both retentivity and coercivity decreases. The hysteresis curve for samples of differing ratios of Gd3+ ions demonstrated the superparamagnetic nature. Tauc’s plot was employed to calculate the energy bandgap (Eg) of synthesized nanoparticles and Eg value were observed to decline from 3.563 eV to 3.521 eV with an increasing Gd3+ ion concentration. Impedance analyzer was used in the frequency range of 100 Hz–100 MHz to study dielectric properties at room temperature. The dielectric parameters declined as the frequency values increased. Due to lower values of dielectric parameters in Gd3+ ion doped Mg–Zn nano-ferrite, these materials are suitable in the fabrication of devices that need to operate at high frequencies such as switching memory storage devices. Moreover, these materials are appropriate for application in ferrofluids and medicinal treatments such as magnetic hyperthermia because of their low coercive field value.

Heating ability of amine functionalized Fe3O4 as a function of field amplitude and frequency for hyperthermia application

The functionalization of magnetic nanoparticles (MNPs) is crucial for their biomedical applications such as magnetic hyperthermia, which attracted attention in recent years as a promising alternative or complementary therapy to traditional cancer treatments. Here, we investigate a synthetic approach based on the hydrothermal process for the amine-functionalized magnetite (Fe3O4-NH2) MNPs for possible use in hyperthermia. The characterization of coated MNPs by FTIR confirms the functionalization with the amine group, while the XRD shows how the magnetite phase was formed. Magnetic measurements of both coated and uncoated MNPs at room temperature revealed their ferrimagnetic behavior. It was found from magnetic hyperthermia measurements under an alternating magnetic field (AMF) that functionalized with amine MNPs reach hyperthermia temperatures (42 °C)) in relatively short times (around 10 min.) with a adequate value of sample absorption rate (SAR)in the range between 33 to 45 W g–1. The (NH2) groups on the surface of the (Fe3O4) nanoparticles prepared by hydrothermal process make them amenable to further functionalization with various biomolecules. This enables the nanoparticles to be tailored for specific applications, such as drug delivery or targeting specific cells or tissues. Moreover, the appropriate crystallinity combined with the relatively adequate heating ability and adequate saturation suggest that the functionalized MNPs are promising for hyperthermia application.

Technical advances in motion-robust MR thermometry.

Proton resonance frequency shift (PRFS) MR thermometry is the most common method used in clinical thermal treatments because of its fast acquisition and high sensitivity to temperature. However, motion is the biggest obstacle in PRFS MR thermometry for monitoring thermal treatment in moving organs. This challenge arises because of the introduction of phase errors into the PRFS calculation through multiple methods, such as image misregistration, susceptibility changes in the magnetic field, and intraframe motion during MRI acquisition. Various approaches for motion correction have been developed for real-time, motion-robust, and volumetric MR thermometry. However, current technologies have inherent trade-offs among volume coverage, processing time, and temperature accuracy. These tradeoffs should be considered and chosen according to the thermal treatment application. In hyperthermia treatment, precise temperature measurements are of increased importance rather than the requirement for exceedingly high temporal resolution. In contrast, ablation procedures require robust temporal resolution to accurately capture a rapid temperature rise. This paper presents a comprehensive review of current cutting-edge MRI techniques for motion-robust MR thermometry, and recommends which techniques are better suited for each thermal treatment. We expect that this study will help discern the selection of motion-robust MR thermometry strategies and inspire the development of motion-robust volumetric MR thermometry for practical use in clinics.

Dynamical analysis of a ferrofluid subjected to oscillatory field and shear rates: Applications to magnetic hyperthermia

The dynamical magnetic response of a small sample of ferrofluid is investigated numerically. A validated in-house research code is used to compute the translational and rotational motion of the particles. This code uses a robust scheme of Ewald summation to compute long-range periodic torques and forces between the particles. The model of the ferrofluid consists in a suspension of magnetic hard spheres replicated in lattices to ensure the convergence of the system’s transport properties. Ensemble averages over several realizations for each simulation are carried out. The suspension is subjected to field and shear time-dependent excitations. The effect of magnetic hyperthermia is evaluated by the average rate of internal energy dissipation due to an oscillatory magnetic field and oscillatory shear rate. Nonlinear dynamical tools such as phase spaces and Poincaré maps are applied to interpret the dynamical behavior of the suspension. Results show that when the suspension reaches its saturation magnetization due to a delayed time-response of the particles the internal energy dissipation decreases with respect to the local applied field. The Poincaré maps reveal that in dilute regimes the system presents quasi-periodic behavior for an alternating magnetic field. Also, the application of an oscillatory shear-rate increases the bulk internal energy of the system due to the magneto-viscous effect, even though it diminishes the internal area of the hysteresis loop. This work brings a better understanding of the dynamical response of ferrofluids that could be useful in magnetic hyperthermia applications.