Bulletin of the American Physical Society
APS March Meeting 2021
Volume 66, Number 1
Monday–Friday, March 15–19, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session B15: Magnetism in BiomedicineLive
|
Hide Abstracts |
Sponsoring Units: GMED GMAG Chair: Hariharan Srikanth, University of South Florida; Stephen Russek, National Institute of Standards and Technology Boulder |
Monday, March 15, 2021 11:30AM - 11:42AM Live |
B15.00001: Particle size-dependent magnetic hyperthermia in gadolinium silicide micro- and nano-particles from calorimetry and AC magnetometry Zoe Boekelheide, Shivakumar G Hunagund, Zainab A Hussein, Jackson T Miller, Ahmed A El-Gendy, Magundappa Hadimani Self-regulating magnetic hyperthermia, in which heating of magnetic particles is limited by the magnetic transition temperature, could be a valuable form of magnetic hyperthermia for cancer treatment, as it can ensure uniform heating across tumor tissue. Gadolinium silicide has been suggested as a candidate material for self-regulating magnetic hyperthermia because of its high magnetization, Curie temperature (TC) near the desired treatment temperature, and tunability. This work presents measurements of size-separated ball-milled Gd5Si4 particles, showing that the magnetization and specific loss power both decrease with decreasing particle size. Dynamic hysteresis loop measurements show that the coercivity of the particles is increased under the conditions used for magnetic hyperthermia (224 kHz, particles dispersed in water) relative to quasistatic measurements of powder samples. However, no particle size-dependence of the coercivity was observed. This work highlights one of the challenges of implementing self-regulating magnetic hyperthermia: materials tend to have low coercivity near TC. Given this challenge, rare-earth compounds with high magnetization may provide the best opportunity to obtain significant heating for self-regulating hyperthermia. |
Monday, March 15, 2021 11:42AM - 11:54AM Live |
B15.00002: Quintuple Carbon Steel Core Coil for Highly Focused Transcranial Magnetic Stimulation in Small Animals Ivan Carmona, Deepak Kumbhare, Mark S. Baron, Magundappa Hadimani Transcranial magnetic stimulation (TMS) is a non-invasive neuromodulation technique used to regulate the synaptic activity of neurons, bringing effective treatment to different neurological and psychiatric disorders. Its induced E-field needs to be focused enough to avoid unwanted overstimulation out of the target region. TMS in small animals like rodents [1] is highly constrained [2,3,4], since most of its studies use equipment with power and coils not designed for small animals. Using FEM in ANSYS Maxwell, we obtained results for a customized array of five double-winding solenoids to restrict the stimulation to areas as small as 1mm2. Each solenoid of 2X25 turns includes a core with V-shape tip sharpening made of steel 1010 of 2T of saturation B at 4×104 A/m. E and B fields were calculated 4.00 mm below the coil (cortical layer 5/6 in rat brains) with a single non-repetitive pulse of current of 5kA at 2.5kHz. The achieved 100V/m in a small target of 1mm2 suggests the suitability of the coil to perform in-vivo experimentation on rodents. |
Monday, March 15, 2021 11:54AM - 12:06PM Live |
B15.00003: Dual-mode nanoparticle MRI contrast agents Edward Van Keuren, Xiaowan Zheng, Vidumin Dahanayake, Trevor Lyons, Sarah Stoll, Christopher Albanese, Stanley Fricke, Olga Rodriguez Contrast agents (CAs) can greatly improve the sensitivity and resolution in Magnetic Resonance Imaging (MRI). Various CAs are commercially available for both T1-weighted (e.g. gadolinium chelates) and T2-weighted (e.g. iron oxide nanoparticles) imaging. We have developed a series of CAs based on Fe and Mn oxo-metallic clusters encapsulated in polymer nanoparticles which display a large contrast enhancement for both T1- and T2- imaging. This creates the opportunity for dual-mode imaging combining T1- and T2- weighted images for enhanced sensitivity and resolution. We will discuss the synthesis of these materials and the development of image fusion algorithms for dual T1-T2 imaging. |
Monday, March 15, 2021 12:06PM - 12:18PM Live |
B15.00004: Temperature maps and accuracy in Magnetic Resonance Imaging thermometry using temperature sensitive superparamagnetic particles Janusz Hankiewicz, Karl F. Stupic, Zbigniew J Celinski, Marek Przybylski
|
Monday, March 15, 2021 12:18PM - 12:30PM Live |
B15.00005: Self-assembly of superparamagnetic nanoparticles used in MRI thermometry John Stroud, Dorota Lachowicz, Janusz Hankiewicz Self-assembly of superparamagnetic nanoparticles has been a highly studied topic, both as an interesting problem and for a wide range of practical applications such as storage media and biomedical technologies [1]. During a recent study of superparamagnetic nanoparticles utilized as temperature sensitive contrast agents for Magnetic Resonance Imaging, we have found that synthesized superparamagnetic nanoparticles (mixed ferrite of 10 nm size) under no applied magnetic field form pentagonal rings. It has been shown theoretically that pentagonal rings are a minimal energy configuration for self-assembly of spherical magnetic nanoparticles [2]. In this work we analyze the effects of the local magnetic fields generated by these pentagonal structures on water proton nuclear magnetic relaxation. These results are important for further understanding of local magnetic fields generated by such assemblies and how they affect temperature dependent MRI imaging using magnetic nanoparticles as contrast agent. |
Monday, March 15, 2021 12:30PM - 12:42PM Live |
B15.00006: Tuning the heating efficiency of hybrid core/shell nanoparticles by modulating the shell composition and thickness Gabriel Lavorato, Raja Das, Yutao Xing, Joshua Robles, Supun B Attanayake, F. Jochen Litterst, Elisa Baggio-Saitovitch, Manh-Huong Phan, Hariharan Srikanth Exchange-coupled ferrite nanostructures are promising candidates to optimize the heating power of magnetic colloids under radiofrequency magnetic fields. We studied Fe3O4/CoxZn1-xFe2O4 core/shell nanoparticles with 12 nm cores and variable shell composition (x=0-1) and thickness (t=0-4 nm). Due to the symmetry and lattice matching between both phases, the Zn-Co ferrite is epitaxially grown on the magnetite, and prevents its oxidation. By applying magnetic fields (f=309 kHz, H=100-800 Oe) to nanoparticles either dispersed in water or fixed in an agar matrix, we found the conditions that maximize the dissipated power in each case. While x=0.5 and t=3 nm are preferred for water colloids at large H, x=0 and t=2 nm provide an efficient heating for agar gel dispersions at low H. We discuss the influence of the overall effective anisotropy (determined by both x and t) on the heating mechanisms. While the Brown-relaxation governs the dissipation of water colloids with large anisotropies and a purely Néel process is observed for isolated particles in agar, interparticle interactions are responsible for large heating powers (above 2000 W/g) in water colloids with low anisotropies. |
Monday, March 15, 2021 12:42PM - 12:54PM Live |
B15.00007: Hydraulic Permeability reconstruction in Magnetic Resonance Elstography Damian Sowinski, Matthew McGarry, Scott Gordon-Wiley, John Weaver, Keith Paulsen Magnetic Resonance Elastography (MRE) is a rapidly developing, non-invasive, imaging technique for acquiring information about tissue properties similar to the way surgeons use manual palpation. At the mm3 voxel level, tissue is treated as a coarse grained medium - much of the MRE field has assumed that using a viscoelastic continuum is sufficient to characterize wave propogation within tissue. Poroelasticity, on the other hand, is a coarse grained description of a viscoelastic porous skeleton interacting with a fluid - qualitatively more in line with what we know tissue is like. I will explore recent advances made by our group in applying poroelasticity to MRE data, focusing on the inference of hydraulic permeability - a tissue's capacity for permitting fluid to filtrate through it - in both simulations and phantoms, paving the way for eventual clinical use. |
Monday, March 15, 2021 12:54PM - 1:06PM Live |
B15.00008: Analysis of resting motor threshold, coil-cortex distance and IC3-IC4 functional connectivity in schizophrenia patients during transcranial magnetic stimulation Emily Cheng, Ananda Pandurangi, Uravakhsh Mehta, Magundappa Hadimani Finite element model (FEM) simulations of transcranial magnetic stimulation (TMS) on heterogeneous head models have been conducted to show stimulation strengths within the brain, a comparison between clinical resting motor threshold (RMT) data and simulation data has not been analyzed. We developed anatomically accurate head models of 20 schizophrenia patient using thier MRIs in SimNIBS pipeline. We then utilized FEM software to compute induced electric fields using patient’s clinical parameters during their investigational procedure. In this way, the simulations were based on real patient data and completely customized to each subject. The electric field induced in the brain was recorded and compared with variables such as cortex-coil distance (CCD), age, and RMT. Our results show that there is little to no correlation between the measured CCD at M1 and the clinically-reported RMT or the maximum electric field recorded in the brain after TMS was simulated using Sim4Life. Thus, we hypothesize that the lack of clear correlation between the CCD at M1 and the measured RMT suggests that there are many other variables which may be influencing an individual’s RMT, beyond the CCD. |
Monday, March 15, 2021 1:06PM - 1:18PM Live |
B15.00009: A lattice Boltzmann method for simulation of diffusion-weighted MRI in biological tissue Noel Naughton, John Georgiadis The lattice Boltzmann method (LBM) is used to integrate the Bloch-Torrey equation, which describes the evolution of the magnetization signal in diffusion-weighted magnetic resonance imaging (dMRI). Motivated by the need to interpret dMRI experiments in biological tissues, a hybrid LBM scheme is developed that accommodates piece-wise uniform transport, MRI sequence parameters, and periodic outer boundary conditions. A membrane boundary condition is implemented that accurately represents the effects of thin curvilinear membranes with finite membrane permeabilities as typically found in biological tissues. In comparison with analytical solutions of limiting cases, the hybrid LBM scheme maintains second-order spatial accuracy, stability, and first-order temporal accuracy for a wide range of parameters. Along with offering certain advantages over finite element or Monte Carlo schemes, the proposed hybrid LBM constitutes a flexible scheme that can by easily adapted to model more complex interfacial conditions and physics in heterogeneous, multiphase tissue models and to accommodate sophisticated dMRI sequences. |
Monday, March 15, 2021 1:18PM - 1:54PM Live |
B15.00010: Magnetism in Medicine: Magnetic Particle Imaging and Beyond Invited Speaker: Steve Connolly As discussed by GMAG and GMED conference committees |
Monday, March 15, 2021 1:54PM - 2:06PM Live |
B15.00011: Standards for Spin-Based Diffusion Measurements for Quantitative MRI Stephen Russek Diffusion coefficients of water and small biological molecules are important biomarkers used in cancer and neurologic imaging. Diffusion in tissue may be anisotropic, non-gaussian, vary on different length scales, and complicated due to perfusion and flow. Spin-based nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) techniques are routinely used to measure and map self-diffusion. Here, we discuss standards for MRI-based diffusion measurements including the development of reference materials, phantoms, validated protocols, and the determination of uncertainties using Monte Carlo based solutions of the Bloch-Torrey equations. Uncertainties are due to NMR/MRI system imperfections (magnetic gradient nonuniformities, eddy currents, nonuniform RF spin excitation), spin dynamics/transport model inadequacy, and material complexity (multiple interreacting spin-populations). We present an examination of uncertainties in simple materials such as water, moderately complex materials such as polymer solutions, and finally in tissue. We compare uncertainties in complex spin manipulation pulse sequences, such as those used in neural MRI, to basic pulsed gradient spin echo sequences. |
Monday, March 15, 2021 2:06PM - 2:18PM Live |
B15.00012: Role of magnetic anisotropy on the hyperthermia efficiency of spherical Fe3-xCoxO4 (x = 0 – 1) nanoparticles Raja Das, Kim Ngoc Pham, Supun B Attanayake, Manh-Huong Phan, Hariharan Srikanth Alternating current (AC) hyperthermia therapy using magnetic nanoparticles has shown potential to replace or supplement well-established cancer treatments, such as radiotherapy and chemotherapy that have severe side effects. The majority of magnetic hyperthermia is to create nanomaterials with improved heating efficiency and long blood circulation time. In this study, we demonstrate a simple strategy to enhance the heating efficiency of Fe3O4 nanoparticles through substitution of Fe+2 ions with Co+2 ions. Magnetic and hyperthermia experiments on the 7 nm Fe3-xCoxO4 (x = 0 – 1) nanoparticles showed that the Blocking temperature (TB), the coercive field (HC) at 10 K, and the specific absorption rate (SAR) followed a similar trend with a maximum at x = 0.75, which is in corroboration with the theoretical prediction. Our study revealed that the heating efficiency of the Fe3-xCoxO4 nanoparticles not only depends on the saturation magnetization and size but also on their magnetocrystalline anisotropy. |
Monday, March 15, 2021 2:18PM - 2:30PM Live |
B15.00013: A Novel Magnetic Respiratory Sensor for Human Healthcare Monitoring Kee Young Hwang, Valery Ortiz Jimenez, Baleeswaraiah Muchharla, Manh-Huong Phan Breathing is vital to life. Therefore, the real-time monitoring of a patient’s breathing pattern is crucial to respiratory rehabilitation therapies. Existing respiratory devices are often in direct contact with a patient, yielding inaccurate or limited data. In this study, we have developed a novel, non-invasive, and contactless magnetic sensing platform that can precisely monitor a patient’s breathing, movement, or sleep patterns. A magneto-LC resonance (MLCR) sensor converts the magnetic oscillations generated by a patient’s breathing into an impedance spectrum, which allows for a deep analysis of one’s breath variation to identify respiratory-related diseases like COVID-19. Owing to its ultrahigh sensitivity, the MLCR sensor yields a distinct breathing pattern for each patient tested, which is superior to existing respiratory devices. The sensor also provides an accurate measure of the strength of a patient’s breath at multiple stages as well as anomalous variations in respiratory rate and amplitude. Using music, we demonstrate the possibility of using MLCR technology to treat patients with chronic pulmonary diseases. This device can also be used to help those who suffer from anxiety or insomnia. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700