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Radiographics : a Review Publication of... 2018The number of patients receiving cochlear implants and auditory brainstem implants for severe to profound sensorineural hearing loss has rapidly increased. These... (Review)
Review
The number of patients receiving cochlear implants and auditory brainstem implants for severe to profound sensorineural hearing loss has rapidly increased. These implants consist of an internal component implanted between the skull and the temporal scalp and an external removable speech processor unit. A small magnet within the internal component is commonly used to hold the external speech processor unit in place. Several cochlear implant models have recently received U.S. Food and Drug Administration and European Economic Area regulatory approval to allow magnetic resonance (MR) imaging examinations to be performed under certain specified conditions. The small internal magnet presents a challenge for imaging of the head and neck near the implant, creating a nonlinear magnetic field inhomogeneity and significant MR imaging artifacts. Fat-saturation failures and susceptibility artifacts severely degrade image quality. Typical artifacts at diffusion-weighted imaging and accelerated imaging are exacerbated. Each examination may require impromptu adjustments to allow visualization of the tissue or contrast of interest. Patients may also be quite uncomfortable during the examination, as a result of either imposed magnetic forces or a tight head wrap that is often applied to minimize internal magnet movement. Translational forces and torque sometimes displace the implanted magnet even when a head wrap is used. Diseases such as neurofibromatosis type 2 that are associated with bilateral vestibular schwannomas and hearing loss often require lifelong tumor surveillance with MR imaging. A collaborative team of radiologists, technologists, and/or medical physicists or MR imaging scientists, armed with strategies to mitigate artifacts near implanted magnets, can customize the examination for better visualization of tissue and consistent comparison examinations over time. RSNA, 2018.
Topics: Artifacts; Cochlear Implants; Humans; Magnetic Resonance Imaging; Magnets; Risk Factors
PubMed: 29320320
DOI: 10.1148/rg.2018170135 -
Analytical and Bioanalytical Chemistry Mar 2016In this critical review we discuss the most recent advances in the field of biosensing applications of magnetic glyconanoparticles. We first give an overview of the main... (Review)
Review
In this critical review we discuss the most recent advances in the field of biosensing applications of magnetic glyconanoparticles. We first give an overview of the main synthetic routes to obtain magnetic-nanoparticle-carbohydrate conjugates and then we highlight their most promising applications for magnetic relaxation switching sensing, cell and pathogen detection, cell targeting and magnetic resonance imaging. We end with a critical perspective of the field, identifying the main challenges to be overcome, but also the areas where the most promising developments are likely to happen in the coming decades.
Topics: Animals; Biosensing Techniques; Carbohydrates; Cell Separation; Cell Tracking; Chemistry Techniques, Synthetic; Humans; Magnetic Resonance Imaging; Magnetics; Magnets; Nanoparticles; Nanotechnology
PubMed: 26282487
DOI: 10.1007/s00216-015-8953-2 -
Scientific Reports Jul 2022Magnetic compression technique (MCT) is a popular new anastomosis method. In this paper, we aimed to explore the feasibility of use of MCT for performing cystotomy in...
Magnetic compression technique (MCT) is a popular new anastomosis method. In this paper, we aimed to explore the feasibility of use of MCT for performing cystotomy in rabbits. The parent magnets and daughter magnets for rabbit cystostomy were designed and manufactured according to the anatomical characteristics of rabbit lower urinary tract. Twelve female New Zealand rabbits were used as animal models. After anesthesia, a daughter magnet was inserted into the bladder through the urethra, and the parent magnet was placed on the body surface projection of the bladder over the abdominal wall. The two magnets automatically attract each other. Postoperatively, the state of magnets was monitored daily, and the time when the magnets fell off was recorded. Cystostomy with MCT was successfully performed in all twelve rabbits. The mean operation time was 4.46 ± 0.75 min. The magnets fell off from the abdominal wall after a mean duration of 10.08 ± 1.62 days, resulting in the formation of bladder fistula. Macroscopic and microscopic examination showed that the fistula was well formed and unobstructed. The junction between bladder and abdominal wall was tight and smooth. We provide preliminary experimental evidence of the safety and feasibility of cystostomy based on MCT.
Topics: Animals; Cystostomy; Female; Magnetic Phenomena; Magnetics; Magnets; Pressure; Rabbits
PubMed: 35842556
DOI: 10.1038/s41598-022-16595-4 -
NMR in Biomedicine Jul 2023To describe the construction and testing of a portable point-of-care low-field MRI system on site in Africa.
PURPOSE
To describe the construction and testing of a portable point-of-care low-field MRI system on site in Africa.
METHODS
All of the components to assemble a 50 mT Halbach magnet-based system, together with the necessary tools, were air-freighted from the Netherlands to Uganda. The construction steps included individual magnet sorting, filling of each ring of the magnet assembly, fine-tuning the inter-ring separations of the 23-ring magnet assembly, gradient coil construction, integration of gradient coils and magnet assembly, construction of the portable aluminum trolley and finally testing of the entire system with an open source MR spectrometer.
RESULTS
With four instructors and six untrained personnel, the complete project from delivery to first image took approximately 11 days.
CONCLUSIONS
An important step in translating scientific developments in the western world from high-income industrialized countries to low- and middle-income countries (LMICs) is to produce technology that can be assembled and ultimately constructed locally. Local assembly and construction are associated with skill development, low costs and jobs. Point-of-care systems have a large potential to increase the accessibility and sustainability of MRI in LMICs, and this work demonstrates that technology and knowledge transfer can be performed relatively seamlessly.
Topics: Point-of-Care Systems; Equipment Design; Magnetic Resonance Imaging; Africa; Magnets
PubMed: 36914258
DOI: 10.1002/nbm.4917 -
Journal of Nursing Management May 2022To identify the relationship between the characteristics of hospitals in recruiting and retaining nurses (magnet properties) and nurses' professional values.
AIM
To identify the relationship between the characteristics of hospitals in recruiting and retaining nurses (magnet properties) and nurses' professional values.
BACKGROUND
In Turkey, there are a limited number of hospitals with the characteristics to enable nurses to stay in their institutions. The magnet properties of these hospitals and the professional values of the nurses working in these hospitals are not known.
METHODS
This descriptive cross-sectional research included 612 nurses working in six hospitals accredited by the Joint Commission International. Data were collected using the Nursing Professional Values Scale-Revised (NPVS-R) and the Essentials of Magnetism Scale (EOM II).
RESULTS
The mean NPVS-R score was high 102.0 (26-130). However, the mean EOM II score was found to be low at 2.2 (1.0-3.4). As the magnet properties of the hospitals increased, the professional values of the nurses decreased.
CONCLUSION
There was a negative correlation between the magnet properties of hospitals and the professional values of the nurses.
IMPLICATIONS FOR NURSING MANAGEMENT
The findings of this study highlight the necessity of creating a working environment with high magnet characteristics, which also includes the professional values of nurses. Nurse managers should investigate the reasons behind the low magnet properties of hospitals, raise awareness, and plan interventions to increase magnet properties of hospitals. Creating a supportive working environment, promotion of the salaries and work environment and decreasing workload are some of the important intervention areas in attracting and keeping nurses in the institution.
Topics: Cross-Sectional Studies; Hospitals; Humans; Job Satisfaction; Magnets; Nursing Staff, Hospital
PubMed: 35293059
DOI: 10.1111/jonm.13589 -
Biosensors & Bioelectronics Feb 2023The process of developing an end-to-end model of a magneto-immunoassay is described, simulating the agglutination effect due to the specific binding of bacteria to...
The process of developing an end-to-end model of a magneto-immunoassay is described, simulating the agglutination effect due to the specific binding of bacteria to paramagnetic particles. After establishing the properties of the dose-specific agglutination through direct imaging, a microfluidic assay was used to demonstrate changes in the magnetophoretic transport dynamics of agglutinated clusters via transient inductive magentometer measurements. End-to-end mathematical modelling is used to establish the physical processes underlying the assay. First, a modified form of Becker-Döring nucleation kinetic equations is used to establish a relationship between analyte dose and average cluster size. Next, Stokes flow equations are used to establish a relationship between cluster size and speed of motion within the fluid chamber. This predicts a cluster-size dynamic profile of concentration of PMPs versus time when the magnetic field is switched between the two actuated magnets. Finally, inductive modelling is carried out to predict the response of the magnetometer circuit in response to the dynamics of magnetic clusters. The predictions of this model are shown to agree well with the results of experiments, and to predict the shape of the dose-response curve.
Topics: Biosensing Techniques; Models, Theoretical; Magnetics; Magnets; Motion
PubMed: 36502714
DOI: 10.1016/j.bios.2022.114745 -
Cells Mar 2022The importance of magnetic micro- and nanoparticles for applications in biomedical technology is widely recognised. Many of these applications, including tissue... (Review)
Review
The importance of magnetic micro- and nanoparticles for applications in biomedical technology is widely recognised. Many of these applications, including tissue engineering, cell sorting, biosensors, drug delivery, and lab-on-chip devices, require remote manipulation of magnetic objects. High-gradient magnetic fields generated by micromagnets in the range of 10-10 T/m are sufficient for magnetic forces to overcome other forces caused by viscosity, gravity, and thermal fluctuations. In this paper, various magnetic systems capable of generating magnetic fields with required spatial gradients are analysed. Starting from simple systems of individual magnets and methods of field computation, more advanced magnetic microarrays obtained by lithography patterning of permanent magnets are introduced. More flexible field configurations can be formed with the use of soft magnetic materials magnetised by an external field, which allows control over both temporal and spatial field distributions. As an example, soft magnetic microwires are considered. A very attractive method of field generation is utilising tuneable domain configurations. In this review, we discuss the force requirements and constraints for different areas of application, emphasising the current challenges and how to overcome them.
Topics: Cell Separation; Magnetic Fields; Magnetics; Magnets; Nanoparticles
PubMed: 35326401
DOI: 10.3390/cells11060950 -
Handbook of Clinical Neurology 2016Magnetic resonance imaging (MRI) works on the principle that hydrogen molecules, which are abundant in organic tissue, have a magnetic moment arising from the spin of... (Review)
Review
Magnetic resonance imaging (MRI) works on the principle that hydrogen molecules, which are abundant in organic tissue, have a magnetic moment arising from the spin of the protons in the nucleus. All atoms consist of a nucleus made of protons and neutrons. When a sample is put in a large magnet field, the hydrogen atoms become magnetized resulting in a bulk magnetization of the sample. Each of these hydrogen atoms acts like a bar magnet, spinning at a frequency about the applied main magnetic field. The frequency of spin is proportional to the applied main field and hence to encode position, we apply an additive field that increases linearly with position in a given direction. Hence, the spins in that direction will precess at a linearly increasing frequency and can be resolved by matching each resolvable frequency bin to a given position. This allows one direction to be resolved. By repeating the same procedure for the other dimension, a 2D image can be resolved by averaging over the third dimension.
Topics: Human Body; Humans; Image Processing, Computer-Assisted; Magnetic Resonance Imaging; Magnetics; Physical Phenomena; Physics; Radio Waves; Time Factors
PubMed: 27432658
DOI: 10.1016/B978-0-444-53485-9.00002-7 -
International Journal of Biological... Dec 2018Enzymes are highly efficient biocatalysts and widely employed in biotechnological sectors. However, lack of (re)-purification and efficient recovery of enzymes are among... (Review)
Review
Enzymes are highly efficient biocatalysts and widely employed in biotechnological sectors. However, lack of (re)-purification and efficient recovery of enzymes are among the most critical and challenging aspects, which render them enormously expensive for industrial exploitability. Aiming to tackle these challenges, magnetic nanoparticles (MNPs) have gained a special place as versatile carriers and supporting matrices for immobilization purposes, owing to the exceptional properties of MNPs, such as large surface area, large surface-to-volume ratio, and mobility and high mass transference. More importantly, they can also be easily separated and recovered by applying an external magnetic field. Apart from their biocompatible micro-environment, the utilization of such MNPs represents a noteworthy green chemistry approach, since it lengthens the biocatalyst lifetime through multiple recovery cycles. According to the literature evidence, various modification and/or functionalization approaches have been developed to produce MNPs for the effective immobilization of a broad variety of industrially important enzymes and biomolecules with improved characteristics. Enzymes immobilized on MNPs displayed a wide-working pH and temperature range, as well as, improved thermal and storage stabilities than that of their pristine counterparts. Co-immobilization of multi-enzymes could also be accomplished through nanoparticle-based approaches. This review presents an updated outlook on the development and characterization of MNPs, in particular, iron-based MNPs-derived nano-constructs as support materials for enzyme immobilization.
Topics: Enzymes, Immobilized; Magnets; Nanoparticles; Surface Properties
PubMed: 30201561
DOI: 10.1016/j.ijbiomac.2018.09.025 -
Biosensors & Bioelectronics Apr 2017Though the magnetoimpedance effect was discovered two decades ago, the biomedical applications of the magnetoimpedance sensor are still in their infancy. In this review,... (Review)
Review
Though the magnetoimpedance effect was discovered two decades ago, the biomedical applications of the magnetoimpedance sensor are still in their infancy. In this review, the authors summarized the magnetoimpedance effect in soft ferromagnetic wires, ribbons and thin films for biosensing applications. Recent progress and achievements of the magnetoimpedance-based biosensing applications including the detection of magnetic Ferrofluid, magnetic beads, magnetic nanoparticles, magnetically labeled bioanalytes and biomagnetic fields of living systems were reviewed. The modification effect of the biochemical liquids, agglomeration effect of the magnetic particles, and the effect of the stray magnetic field on magnetoimpedance were investigated in this review. Some constructive strategies were proposed for design of the high-performance magnetoimpedance biosensor, for quantitative and ultrasensitive detection of magnetically labeled biomolecules. The theoretical and experimental results suggest that the magnetoimpedance sensors are particularly suitable for highly sensitive detection of low-concentration biomolecules, and might be used for early diagnosis and screening of cancers.
Topics: Biosensing Techniques; Dielectric Spectroscopy; Electric Impedance; Magnetic Fields; Magnets; Nanoparticles
PubMed: 27825890
DOI: 10.1016/j.bios.2016.10.031