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PurposeThe aim of this study is to prospectively evaluate whether women with copper-containing intrauterine devices (Cu-IUD), currently listed as MR conditional, can safely undergo 3.0 Tesla (3 T) magnetic resonance imaging (MRI).Methods73 women, age 18-54 years old, with a Cu-IUD who were undergoing MRI for any reason were included consecutively. Pre- and post-MRI standard pelvic ultrasound examinations were completed to determine the appropriate pre- and post-MRI positioning of the Cu-IUD. Displaced IUDs were defined by IUD crossbars not in the fundal portion of the endometrial cavity, a visualized tip in the mid or lower uterus, any part of the device located in the cervical canal or outside of the endometrial canal, a fractured device, or a non-visualized IUD. Additionally, a questionnaire was completed by participants to determine the level of pre- and post-MRI pelvic pain.ResultsThere were zero observed displaced Cu-IUDs on post-MRI pelvic ultrasounds (p = 0/70, 95% CI 0, .043). Three participants were dropped from the study due to malpositioned IUDs on pre-MRI pelvic ultrasound. Six patients reported new or worsening pelvic pain/discomfort during or after their MRI examination.ConclusionOur results suggest that performing 3 T MRI using a low SAR setting does not cause displacement of Cu-IUDs, with zero out of 70 patients demonstrating IUD displacement.

Purpose: Peripheral nerve stimulation (PNS) limits the usability of state‐of‐the‐art whole‐body and head‐only MRI gradient coils. We used detailed electromagnetic and neurodynamic modeling to set an explicit PNS constraint during the design of a whole‐body gradient coil and constructed it to compare the predicted and experimentally measured PNS thresholds to those of a matched design without PNS constraints. Methods: We designed, constructed, and tested two actively shielded whole‐body Y‐axis gradient coil winding patterns: YG1 is a conventional symmetric design without PNS‐optimization, whereas YG2's design used an additional constraint on the allowable PNS threshold in the head‐imaging landmark, yielding an asymmetric winding pattern. We measured PNS thresholds in 18 healthy subjects at five landmark positions (head, cardiac, abdominal, pelvic, and knee). Results: The PNS‐optimized design YG2 achieved 46% higher average experimental thresholds for a head‐imaging landmark than YG1 while incurring a 15% inductance penalty. For cardiac, pelvic, and knee imaging landmarks, the PNS thresholds increased between +22% and +35%. For abdominal imaging, PNS thresholds did not change significantly between YG1 and YG2 (−3.6%). The agreement between predicted and experimental PNS thresholds was within 11.4% normalized root mean square error for both coils and all landmarks. The PNS model also produced plausible predictions of the stimulation sites when compared to the sites of perception reported by the subjects. Conclusion: The PNS‐optimization improved the PNS thresholds for the target scan landmark as well as most other studied landmarks, potentially yielding a significant improvement in image encoding performance that can be safely used in humans. [ABSTRACT FROM AUTHOR]

ASTM (American Society for Testing and Materials) F2052-21 (Chinese corresponding standard titled as YY/T 0987.2) introduces a test method to measure the magnetically induced displacement force on medical devices in the magnetic resonance environment. This method has been widely accepted and utilized globally, which is intended for implantable medical devices that can be suspended from a string. The angular deflection of the string from the vertical is measured and thereby measuring out the magnitude of the magnetically induced deflection force relative to gravity. When applying this method on ultralight implants, it is practically almost impossible to use a suspension string that weighs less than 1% of the mass of the implant. That study proposes a method for measuring the magnetically induced displacement force on ultralight implants based on counterweight correction by using a string and clamp that exceed 1% of the weight of the implant. And then to measure the deflection angle according to the standard requirement, following that to correct the deflection angle by using the proportion of the mass of the implant under test to the total mass of the tested object, to obtain the measurement result. That study also provides theoretical calculations and experimental verification to the counterweight correction method, the results prove that the proposed method can effectively measure the magnetically induced displacement force on ultralight implants.

Purpose: To demonstrate the performance of gradient array coils in minimizing switched‐gradient‐induced electric fields (E‐fields) and improving peripheral nerve stimulation (PNS) thresholds while generating gradient fields with adjustable linearity across customizable regions of linearity (ROLs). Methods: A body gradient array coil is used to reduce the induced E‐fields on the surface of a body model by modulating applied currents. This is achieved by performing an optimization problem with the peak E‐field as the objective function and current amplitudes as unknown variables. Coil dimensions and winding patterns are fixed throughout the optimization, whereas other engineering metrics remain adjustable. Various scenarios are explored by manipulating adjustable parameters. Results: The array design consistently yields lower E‐fields and higher PNS thresholds across all scenarios compared with a conventional coil. When the gradient array coil generates target gradient fields within a 44‐cm‐diameter spherical ROL, the maximum E‐field is reduced by 10%, 18%, and 61% for the X, Y, and Z gradients, respectively. Transitioning to a smaller ROL (24 cm) and relaxing the gradient linearity error results in further E‐field reductions. In oblique gradients, the array coil demonstrates the most substantial reduction of 40% in the Z–Y direction. Among the investigated scenarios, the most significant increase of 4.3‐fold is observed in the PNS thresholds. Conclusion: Our study demonstrated that gradient array coils offer a promising pathway toward achieving high‐performance gradient coils regarding gradient strength, slew rate, and PNS thresholds, especially in scenarios in which linear magnetic fields are required within specific target regions. [ABSTRACT FROM AUTHOR]

Devices for the gastrointestinal tract are widely available and constantly advancing with less invasive techniques. They play a crucial role in diagnostic and therapeutic interventions and are commonly placed by interventional radiologists, gastroenterologists, and surgeons. These devices frequently appear in imaging studies, which verify their proper placement, identify any complications, or may be incidentally detected. Radiologists must be able to identify these devices at imaging and understand their intended purpose to assess their efficacy, detect complications such as incorrect positioning, and avoid misinterpreting them as abnormalities. Furthermore, many patients with these devices may require MRI, making assessing compatibility essential for safe patient care. This review seeks to provide a succinct and practical handbook for radiologists regarding both common and uncommon gastrointestinal devices. In addition to textual descriptions of clinical indications, imaging findings, complications, and MRI compatibility, the review incorporates a summary table as a quick reference point for key information and illustrative images for each device. [ABSTRACT FROM AUTHOR]

As magnetic field strength in Magnetic Resonance Imaging (MRI) technology increases, maintaining the specific absorption rate (SAR) within safe limits across human head tissues becomes challenging due to the formation of standing waves at a shortened wavelength. Compounding this challenge is the uncertainty in the dielectric properties of head tissues, which notably affects the SAR induced by the radiofrequency (RF) coils in an ultra-high-field (UHF) MRI system. To this end, this study introduces a computational framework to quantify the impacts of uncertainties in head tissues' dielectric properties on the induced SAR. The framework employs a surrogate model-assisted Monte Carlo (MC) technique, efficiently generating surrogate models of MRI observables (electric fields and SAR) and utilizing them to compute SAR statistics. Particularly, the framework leverages a high-dimensional model representation technique, which constructs the surrogate models of the MRI observables via univariate and bivariate component functions, approximated through generalized polynomial chaos expansions. The numerical results demonstrate the efficiency of the proposed technique, requiring significantly fewer deterministic simulations compared with traditional MC methods and other surrogate model-assisted MC techniques utilizing machine learning algorithms, all while maintaining high accuracy in SAR statistics. Specifically, the proposed framework constructs surrogate models of a local SAR with an average relative error of 0.28% using 289 simulations, outperforming the machine learning-based surrogate modeling techniques considered in this study. Furthermore, the SAR statistics obtained by the proposed framework reveal fluctuations of up to 30% in SAR values within specific head regions. These findings highlight the critical importance of considering dielectric property uncertainties to ensure MRI safety, particularly in 7 T MRI systems. [ABSTRACT FROM AUTHOR]

Introduction: Magnetic resonance imaging (MRI) provides excellent soft tissue contrast for visualizing of deep brain stimulation (DBS) targets, allowing validation of the electrode placement, and assessing complications such as microhemorrhage and edema. However, the presence of the electrodes can introduce challenges such as radiofrequency (RF) induced current artifacts and excessive heating of the electrode contacts. Additionally, extended procedure times are also considered a disadvantage when using MRI as an intraoperative imaging modality following DBS electrode placement. Method: We propose a novel approach of using toroidal resonators to inductively couple the shaft of the electrode to the scanner's transmit-receive chain thereby utilizing it as a localized imaging antenna. The small extent of the field generated by the electrode antenna allows fast imaging with smaller field-of-views (FOVs) spanning only a few centimeters. Furthermore, we present a fast and accurate safety monitoring strategy that can be used to predict the temperature increase at the electrical contacts of the electrode. Results and Discussion: Imaging with the toroidal transceiver yields a higher signal-to-noise ratio (SNR) efficiency in proximity to the electrodes. This approach reduced the RF induced current artifacts around the electrode which enhanced the visibility of the shaft and improved electrode localization. Moreover, the limited sensitivity around the electrode can be exploited to perform fast scans with small FOVs. The predicted heating around DBS contacts was in quantitative agreement with the experimental heating in swine studies with a normalized root-mean-square error (NRMSE) ≤ 0.09.

Acoustic noise from magnetic resonance imaging (MRI) can cause hearing loss and needs to be mitigated to ensure the safety of patients and personnel. Capturing MR personnel's insights is crucial for guiding the development and future applications of noise-reduction technology. This study aimed to explore how MR radiographers manage acoustic noise in clinical MR settings. Using a qualitative design, we conducted semi-structured individual interviews with fifteen MR radiographers from fifteen hospitals around Sweden. We focused on the clinical implications of participants' noise management, using an interpretive description approach. We also identified sociotechnical interactions between People , Environment , Tools , and Tasks (PETT) by adopting a Human Factors/Ergonomics framework. Interview data were analyzed inductively with thematic analysis (Braun and Clarke). The analysis generated three main themes regarding MR radiographers' noise management: (I) Navigating Occupational Noise: Risk Management and Adaptation; (II) Protecting the Patient and Serving the Exam, and (III) Establishing a Safe Healthcare Environment with Organizational Support. This study offers insights into radiographers' experiences of managing acoustic noise within MRI, and the associated challenges. Radiographers have adopted multiple strategies to protect patients and themselves from adverse noise-related effects. However, they require tools and support to manage this effectively, suggesting a need for organizations to adopt more proactive, holistic approaches to safety initiatives. The radiographers stressed the importance of a soundproofed work environment to minimize occupational adverse health effects and preserve work performance. They acknowledge noise as a common contributor to patient distress and discomfort. Providing options like earplugs, headphones, mold putty, software-optimized "quiet" sequences, and patient information were important tools. Fostering a safety culture requires proactive safety efforts and support from colleagues and management. [ABSTRACT FROM AUTHOR]

Strict safety practices are essential to ensure the safety of patients and staff in Magnetic Resonance Imaging (MRI). Training regarding the fundamentals of MRI safety is well-established and commonly agreed upon. However, more complex aspect of screening patients, such as image review or screening of unconscious patients/patients with communication difficulties is less well discussed. The current UK and USA guidelines do not suggest the use of communication training for MRI staff nor indicate any training to encourage reviewing images in the screening process. This review aims to map the current guidance regarding safety and patient screening training for MRI diagnostic and therapeutic radiographers. A systematic search of PubMed, Trip Medical database and Radiography journal was conducted. Studies were chosen based on the review objectives and pre-determined inclusion/exclusion criteria using the PRISMA-ScR framework. Twenty-four studies were included in the review, which identified some key concepts including MRI safety training and delivery methods, screening and communication, screening of unconscious or non-ambulatory patients and the use of imaging. Training gaps lie within the more complex elements of screening such as the inclusiveness of question phrasing, particularly to the neurodivergent population, how we teach radiographers to screen unconscious/unresponsive patients and using imaging to detect implants. The consequences of incomplete or inaccurate pre-MRI safety screening could be the introduction of unexpected implants into the scanner or forgoing MRI for a less desirable modality. The development of enhanced training programs in implant recognition using imaging and communication could complement existing training. [ABSTRACT FROM AUTHOR]

The standard of care for managing a patient with an implant is to identify the item and to assess the relative safety of scanning the patient. Because the 1.5 T MR system is the most prevalent scanner in the world and 3 T is the highest field strength in widespread use, implants typically have "MR Conditional" (i.e., an item with demonstrated safety in the MR environment within defined conditions) labeling at 1.5 and/or 3 T only. This presents challenges for a facility that has a scanner operating at a field strength below 1.5 T when encountering a patient with an implant, because scanning the patient is considered "off‐label." In this case, the supervising physician is responsible for deciding whether to scan the patient based on the risks associated with the implant and the benefit of magnetic resonance imaging (MRI). For a passive implant, the MRI safety‐related concerns are static magnetic field interactions (i.e., force and torque) and radiofrequency (RF) field‐induced heating. The worldwide utilization of scanners operating below 1.5 T combined with the increasing incidence of patients with implants that need MRI creates circumstances that include patients potentially being subjected to unsafe imaging conditions or being denied access to MRI because physicians often lack the knowledge to perform an assessment of risk vs. benefit. Thus, physicians must have a complete understanding of the MRI‐related safety issues that impact passive implants when managing patients with these products on scanners operating below 1.5 T. This monograph provides an overview of the various clinical MR systems operating below 1.5 T and discusses the MRI‐related factors that influence safety for passive implants. Suggestions are provided for the management of patients with passive implants labeled MR Conditional at 1.5 and/or 3 T, referred to scanners operating below 1.5 T. The purpose of this information is to empower supervising physicians with the essential knowledge to perform MRI exams confidently and safely in patients with passive implants. Level of Evidence: 1 Technical Efficacy: Stage 3 [ABSTRACT FROM AUTHOR]

Objective: This study investigates the accuracy of large language models (LLMs) on magnetic resonance imaging (MRI) safety-related questions. Methods: Three experienced radiologists independently prepared 20 multiple-choice questions based on the MRI safety guidelines published by the Turkish Magnetic Resonance Society. An initial prompt was entered into 4 diferent LLMs (ChatGPT-3.5, ChatGPT-4, Gemini, and Perplexity) and then a total of 60 questions were asked. The answers received were compared with the answers assigned by the radiologists according to guidelines. The performance of each model was obtained as accuracy. Results: In 60 questions, the accuracy rates were 78.3% (47/60) for ChatGPT-3.5, 93.3% (56/60) for ChatGPT-4, 88.3% (53/60) for Gemini, and 86.7% (52/60) for Perplexity. In addition, ChatGPT-3.5 answered 19/20, 13/20, and 15/20, ChatGPT-4 answered 18/20, 18/20, and 20/20, Gemini answered 19/20, 18/20, and 16/20, and Perplexity answered 20/20, 15/20, and 17/20 correctly to question groups prepared by 3 radiologists, respectively. Conclusion: Large language models, particularly the most stable and highest performing ChatGPT-4, may be useful to patients and health-care professionals in providing MRI safety-related information. They have the potential to assist in the future to protect health-care professionals and patients from MRI-related accidents. [ABSTRACT FROM AUTHOR]

INTRODUCTION: Image-guided endovascular interventions, performed using the insertion and navigation of catheters through the vasculature, have been increasing in number over the years, as minimally invasive procedures continue to replace invasive surgical procedures. Such endovascular interventions are almost exclusively performed under x-ray fluoroscopy, which has the best spatial and temporal resolution of all clinical imaging modalities. Magnetic resonance imaging (MRI) offers unique advantages and could be an attractive alternative to conventional x-ray guidance, but also brings with it distinctive challenges. AREAS COVERED: In this review, the benefits and limitations of MRI-guided endovascular interventions are addressed, systems and devices for guiding such interventions are summarized, and clinical applications are discussed. EXPERT OPINION: MRI-guided endovascular interventions are still relatively new to the interventional radiology field, since significant technical hurdles remain to justify significant costs and demonstrate safety, design, and robustness. Clinical applications of MRI-guided interventions are promising but their full potential may not be realized until proper tools designed to function in the MRI environment are available. Translational research and further preclinical studies are needed before MRI-guided interventions will be practical in a clinical interventional setting.

Magnetic resonance imaging (MRI) is a non-invasive diagnostic technique widely used in medicine with more than 60 million exams per year performed worldwide. MRI personnel are always exposed to static and spatially heterogeneous magnetic fields (fringe or stray fields) and motion-induced time-varying magnetic fields during the working day. This kind of exposure can evoke vertigo and other sensory perceptions such as nausea, visual sensations, and a metallic taste which are not considered hazardous per se, but can be disturbing and may impair working ability. Up to now, no standardized procedures have been available in the literature for the assessment of occupational exposure in an MRI environment. The goal of this paper is to give some indications about the analytical models underlying the development of digital tools for occupational exposure assessment in MRI environments, to have easy but interactive educational tools, for educating MRI staff to avoid higher-risk conditions, and to draw up the best practices. Analysis of the models for the estimation of the magnetic field spatial distribution and the representation of the workers’ movements is described and finally, some recommendations for an accurate methodology to use in simulation tools for exposure assessment are given.

Purpose: Dental amalgam contains mercury and is commonly used in dental restorations. The impact of MRI on mercury excretion from dental amalgam is not well understood across clinical field strengths, especially 7T. We investigated the effects of MRI exposure on mercury excretion using fresh, lab‐created dental amalgam restorations and in extracted teeth with old, pre‐existing restorations. Methods: Donated, unfilled human teeth (n = 120) were restored with amalgam before being stored in saline, artificial saliva, or a dry box prior to MRI scanning. The teeth were placed in individual tubes of fresh artificial saliva and scanned at 1.5T, 3T, or 7T or left unscanned as controls. Mercury concentrations were measured 24–30 h later. Donated teeth with pre‐existing restorations (n = 40) were stored in artificial saliva, scanned at 7T or left unscanned as controls, and mercury concentration tested. Results: For teeth extracted and restored in a laboratory, no significant difference was found (F = 2.42, P = 0.072) between mean mercury concentrations of unscanned teeth (13.72 μg/L) and teeth scanned at 1.5T (10.88 μg/L), 3T (12.65 μg/L), or 7T (8.88 μg/L). For teeth extracted with previously placed restorations, no significant difference (P = 0.288) was found between unscanned controls (4.28 μg/L) and teeth scanned at 7T (6.63 μg/L). Conclusion: MRI of dental amalgam does not significantly increase mercury excretion at 1.5T, 3T, or 7T compared to unscanned teeth. This holds true for controlled laboratory restorations as well as for those placed and lived with prior to extraction and scanning, demonstrating no added risk to the clinical patient or research subject. [ABSTRACT FROM AUTHOR]

Plain film radiographs are recommended to assist in MRI safety screening of patients with unknown medical histories, especially in an emergency setting where patients might be unable to answer a safety questionnaire. This study assesses the performance of CT scout images, which have low radiation dose and are faster and easier to acquire compared to plain film radiographs, in finding and naming a range of head and body implants. A retrospective analysis of 40 CT Head and Neck (HN) scout images and 40 CT Chest, Abdomen and Pelvis (CAP) scout images was undertaken. A subset of these were chosen to include a range of common internal implants not identifiable externally to the patient. The images were assessed by three readers with varying levels of clinical experience in MRI who were asked to find and name any implants seen. Collectively, all readers reached a sensitivity of 85 % in finding internal implants, regardless of their clinical experience or experience in reviewing CT images, and a minimum specificity of 95 %. Implants were correctly named in 74 % of the images presented. CT scout images were able to reveal most of the implants included. However, clinical experience in reviewing the images enhances a reader's ability to identify the type of implant. In an emergency setting, imaging can be critical in the management of patients presenting with acute illnesses. In the unconscious or unresponsive patient, the use of CT scouts, where this is the only option available, could provide valuable MRI safety information prior to a scan, improving access to the MRI scan in a timely manner. [ABSTRACT FROM AUTHOR]

Objective: There is increased confusion regarding MRI‐compatible CIs and BAHAs. This report describes two cases when patients underwent MRIs with non‐MRI compatible devices. Results: One patient with bilateral Cochlear Osias experienced dislocation of both internal magnets after 1.5 Tesla MRI. Both magnets were outside the silastic sheath, with the left magnet flipped. A second patient with a legacy CI experienced similar internal magnet dislocation and inversion after 3 Tesla MRI. Conclusions: This study describes internal magnet dislocation/inversion with the Cochlear Osia and a legacy CI after MRI. Our findings suggest the need for improved patient education and simplified radiology guidelines. Laryngoscope, 134:393–396, 2024 [ABSTRACT FROM AUTHOR]

As magnetic field strength in Magnetic Resonance Imaging (MRI) technology increases, maintaining the specific absorption rate (SAR) within safe limits across human head tissues becomes challenging due to the formation of standing waves at a shortened wavelength. Compounding this challenge is the uncertainty in the dielectric properties of head tissues, which notably affects the SAR induced by the radiofrequency (RF) coils in an ultra-high-field (UHF) MRI system. To this end, this study introduces a computational framework to quantify the impacts of uncertainties in head tissues’ dielectric properties on the induced SAR. The framework employs a surrogate model-assisted Monte Carlo (MC) technique, efficiently generating surrogate models of MRI observables (electric fields and SAR) and utilizing them to compute SAR statistics. Particularly, the framework leverages a high-dimensional model representation technique, which constructs the surrogate models of the MRI observables via univariate and bivariate component functions, approximated through generalized polynomial chaos expansions. The numerical results demonstrate the efficiency of the proposed technique, requiring significantly fewer deterministic simulations compared with traditional MC methods and other surrogate model-assisted MC techniques utilizing machine learning algorithms, all while maintaining high accuracy in SAR statistics. Specifically, the proposed framework constructs surrogate models of a local SAR with an average relative error of 0.28% using 289 simulations, outperforming the machine learning-based surrogate modeling techniques considered in this study. Furthermore, the SAR statistics obtained by the proposed framework reveal fluctuations of up to 30% in SAR values within specific head regions. These findings highlight the critical importance of considering dielectric property uncertainties to ensure MRI safety, particularly in 7 T MRI systems.

At ultra-high field MRI (Bo>7T) it is crucial to predict and control the patient safety. Commonly patient safety is controlled by the power deposited in the tissue (specific absorption rate - SAR). However, temperature distributions do not always correlate directly with SAR distributions, which makes temperature control also a crucial parameter to guarantee patient safety. In this work, temperature changes were accessed by MR thermometry, specifically by the proton resonance frequency shift technique (PRF). A phantom mimicking muscle tissue was used to evaluate the temperature rise caused by the radiofrequency (RF) absorption during 7T MRI, applied through a commercial birdcage head coil. A pulse-sequence protocol was implemented for both, the generation of temperature increase and the MR thermometry. To control the temperature, a digital thermometer was used, and oil tubes were utilized to dismiss the drift effects for PRF. Measurements of the phantom’s dielectric characteristics, i.e. conductivity and permittivity, were in good agreement with the literature values for muscle. Spatio-temporal evaluations showed a temperature increase in time via RF exposure and the feasibility of measuring temperature maps using the PRF shift method. The accuracy of the PRF shift method increased when the drift effects were quantified and dismissed, indicating a PRF reading accuracy differing less than 0.5 °C from the thermometer. Results also validate our heating and temperature imaging protocol. This study is a valuable contribution to the evaluation of heating effects caused by RF absorption and demonstrates potential impact on future thermal investigations, which may use different heating sources, as well validate thermal simulations.

This position statement guides cardiovascular magnetic resonance (CMR) imaging program directors and learners on the key competencies required for Level II and III CMR practitioners, whether trainees come from a radiology or cardiology background. This document is built upon existing curricula and was created and vetted by an international panel of cardiologists and radiologists on behalf of the Society for Cardiovascular Magnetic Resonance (SCMR).

Considerable immediate safety risks are intrinsic to the magnetic resonance imaging (MRI) environment and must be acknowledged and prevented. The purpose of this study was to analyze the impact of health professionals' characteristics on the mean knowledge in MRI safety domains and identify significant predictors for knowledge in these domains. A convenience sample of 433 participants was recruited from hospitals representing the four major health sectors in the country. The questionnaire consisted of questions about the demographics of the participants and their knowledge of the main domains of MRI safety. Knowledge of the main MRI safety domains and their associated subdomains varied among participants. MRI technologists, workers in private hospitals, and those who had courses/training had higher mean scores in all domains of MRI safety knowledge compared to their counterparts. A statistically significant difference in the participants' knowledge in the four main MRI safety domains based on participants' characteristics. • Knowledge of the main MRI safety domains varied among participating health workers. • Knowledge and awareness of health workers of MRI safety must be evaluated regularly. • MRI safety education/training and experience improve the awareness of possible hazards. [ABSTRACT FROM AUTHOR]

Since the introduction of MRI as a sustainable diagnostic modality, global accessibility to its services has revealed a wide discrepancy between populations—leaving most of the population in LMICs without access to this important imaging modality. Several factors lead to the scarcity of MRI in LMICs; for example, inadequate infrastructure and the absence of a dedicated workforce are key factors in the scarcity observed. RAD‐AID has contributed to the advancement of radiology globally by collaborating with our partners to make radiology more accessible for medically underserved communities. However, progress is slow and further investment is needed to ensure improved global access to MRI. [ABSTRACT FROM AUTHOR]

Purpose: To predict subject‐specific local specific absorption rate (SAR) distributions of the human head for parallel transmission (pTx) systems at 7 T. Theory and methods: Electromagnetic energy deposition in tissues is nonuniform at 7 T, and interference patterns due to individual channels of pTx systems may result in increased local SAR values, which can only be estimated with very high safety margins. We proposed, designed, and demonstrated a multichannel 3D convolutional neural network (CNN) architecture to predict local SAR maps as well as peak‐spatial SAR (ps‐SAR) levels. We hypothesized that utilizing a three‐channel 3D CNN, in which each channel is fed by a B1+$$ {B}_1^{+} $$ map, a phase‐reversed B1+$$ {B}_1^{+} $$ map, and an MR image, would improve prediction accuracies and decrease uncertainties in the predictions. We generated 10 new head–neck body models, along with 389 3D pTx MRI data having different RF shim settings, with their B1 and local SAR maps to support efforts in this field. Results: The proposed three‐channel 3D CNN predicted ps‐SAR10g levels with an average overestimation error of 20%, which was better than the virtual observation points–based estimation error (i.e., 152% average overestimation). The proposed method decreased prediction uncertainties over 20% (i.e., 22.5%–17.7%) compared to other methods. A safety factor of 1.20 would be enough to avoid underestimations for the dataset generated in this work. Conclusion: Multichannel 3D CNN networks can be promising in predicting local SAR values and perform predictions within a second, making them clinically useful as an alternative to virtual observation points–based methods. [ABSTRACT FROM AUTHOR]

Purpose: To propose an efficient numerical method to predict the temperature increase of an implantable medical device induced by any linearly polarized homogeneous magnetic field, according to the ISO 10974 methodology for testing of gradient‐induced device heating. Theory and Methods: The concepts of device‐specific power and temperature tensors are introduced to mathematically describe the electromagnetic and thermal anisotropic behavior of the device, from which the device heating for an arbitrary exposure direction can be predicted. The proposed method is compared to a brute‐force approach based on simulations, and validated by applying it to four reference orthopedic implants with a commercial simulation software. Results: The proposed method requires about 5%$$ \% $$ of the time required by the brute‐force approach, and 30%$$ \% $$ of the memory occupancy. The temperature increase predicted by the proposed method over a range of incident magnetic field exposures deviated from brute‐force direct simulations by less than ±$$ \pm $$0.3%$$ \% $$. Conclusion: The proposed method allows efficient prediction of the heating of an implantable medical device induced by any linearly polarized homogeneous magnetic field using a small fraction of the simulations required by the brute‐force approach. The results can be used to predict the worst‐case orientation of the gradient field, for subsequent experimental characterization according to the ISO 10974 standard. [ABSTRACT FROM AUTHOR]

Adverse reactions in tattooed skin during magnetic resonance imaging (MRI) are rare but well known. Previous reports describe sudden burning pain in tattooed skin, sometimes accompanied by mild erythema and oedema when entering MRI scanners. The pathophysiology remains unclear, but simple direct thermal heating can be excluded. It has been hypothesized that MRI-triggered torque and traction create neural sensations from magnetic pigment particles. However, this case enlightens yet another possible mechanism. We present a 35-year-old woman experiencing reoccurring stinging sensations in three decorative black tattoos just seconds after the initiation of the MRI. Single-blind tests with handheld power magnets or a dummy could reproduce painful subjective feelings in her tattooed skin. Similar events were provoked during re-evaluation with MRI. Surprisingly, chemical analyses and electron microscopy of skin samples revealed carbon black as the colouring agent – no iron-based solids were detected. Our case demonstrates that MRI tattoo reactions are not limited to magnetic contaminants alone. More distinct subgroups of MRI-induced reactions may occur. We hypothesize that radiofrequency induction of surface currents in black carbon particles adjacent to sensory axons in the dermis may lead to neurosensations.

Background: Parallel radiofrequency transmission (pTx) remains a promising technology for addressing high‐field magnetic resonance imaging (MRI) challenges, particularly regarding the safety of patients with implanted deep brain stimulation (DBS) devices. Radiofrequency (RF) shim optimization methods utilizing pTx technology have shown the potential to minimize induced RF heating effects at the electrode tips of DBS devices at 3 T. Purpose: Research pTx system implementations often involve the combination of custom and commercial hardware that are integrated onto an existing MRI system. As a result, system characterization is important to ensure implant‐friendly safe imaging conditions are satisfied for the operating range of the hardware. Methods: Utilizing electromagnetic and thermal simulations, the impact of system uncertainty is studied for the proposed 4‐ and 8‐channel pTx system setup and its associated "safe mode" for DBS applications. Results: Electromagnetic simulations indicated that instrumentation errors can affect the overall electric field strength experienced at the DBS lead tip, and a worst‐case system uncertainty analysis predicted temperature elevations of +1.5°C in the 4‐channel setup and +0.9°C in the 8‐channel setup. Conclusions: In conclusion, system uncertainty can impact the precision of pTx RF inputs which in the worst‐case, may lead to an unsafe imaging scenario and the proposed 8‐channel setup may provide more robustness and thus, safer conditions for MRI of DBS patients. [ABSTRACT FROM AUTHOR]

Purpose: Peripheral nerve stimulation (PNS) limits the image encoding performance of both body gradient coils and the latest generation of head gradients. We analyze a variety of head gradient design aspects using a detailed PNS model to guide the design process of a new high‐performance asymmetric head gradient to raise PNS thresholds and maximize the usable image‐encoding performance. Methods: A novel three‐layer coil design underwent PNS optimization involving PNS predictions of a series of candidate designs. The PNS‐informed design process sought to maximize the usable parameter space of a coil with <10% nonlinearity in a 22 cm region of linearity, a relatively large inner diameter (44 cm), maximum gradient amplitude of 200 mT/m, and a high slew rate of 900 T/m/s. PNS modeling allowed identification and iterative adjustment of coil features with beneficial impact on PNS such as the number of winding layers, shoulder accommodation strategy, and level of asymmetry. PNS predictions for the final design were compared to measured thresholds in a constructed prototype. Results: The final head gradient achieved up to 2‐fold higher PNS thresholds than the initial design without PNS optimization and compared to existing head gradients with similar design characteristics. The inclusion of a third intermediate winding layer provided the additional degrees of freedom necessary to improve PNS thresholds without significant sacrifices to the other design metrics. Conclusion: Augmenting the design phase of a new high‐performance head gradient coil by PNS modeling dramatically improved the usable image‐encoding performance by raising PNS thresholds. [ABSTRACT FROM AUTHOR]

This study aims to assess potential complications and effects on the magnetic resonance imaging (MRI) image quality of a new MRI-conditional breast tissue expander (Motiva Flora®) in its first in-human multi-case application. Twenty-four patients with 36 expanders underwent non-contrast breast MRI with T1-weighted, T2-weighted, and diffusion-weighted imaging (DWI) sequences on a 3 T unit before breast tissue expander exchange surgery, being monitored during and after MRI for potential complications. Three board-certified breast radiologists blindly and independently reviewed image quality using a four-level scale ("poor", "sufficient", "good", and "excellent"), with inter-reader reliability being assessed with Kendall's τb. The maximum diameters of RFID-related artifacts on T1-weighted and DWI sequences were compared with the Wilcoxon signed-rank test. All 24 examinations were completed without patient-related or device-related complications. The T1-weighted and T2-weighted sequences of all the examinations had "excellent" image quality and a median 11 mm (IQR 9–12 mm) RFID artifact maximum diameter, significantly lower (p < 0.001) than on the DWI images (median 32.5 mm, IQR 28.5–34.5 mm). DWI quality was rated at least "good" in 63% of the examinations, with strong inter-reader reliability (Kendall's τb 0.837, 95% CI 0.687–0.952). This first in-human study confirms the MRI-conditional profile of this new expander, which does not affect the image quality of T1-weighted and T2-weighted sequences and moderately affects DWI quality. [ABSTRACT FROM AUTHOR]

The MRI technologist (radiographer) is at the frontline of MRI safety decision-making and has the primary responsibility to provide high quality, efficient and safe patient care in the MRI environment. As MRI technology advances and new safety issues emerge, this study aimed to provide a snapshot of the preparedness of MRI technologists in New Zealand (NZ) and Australia to practise confidently and safely. An online questionnaire, administered via Qualtrics and covering a range of MRI safety topics, was distributed in 2018 via the New Zealand MR Users Group, the MRI Australia-NZ Group Facebook, and relevant professional bodies. A total of 312 MRI technologists attempted the questionnaire, with 246 surveys being fully completed. Of these, 61% (n = 149) were in Australia, 36% (n = 89) in NZ, and 3% (n = 8) from other countries. Findings indicated that current MRI education is preparing MRI technologists in NZ and Australia to practise safely. However, while these technologists are confident in their MRI safety decision-making, accuracy levels within some groups need addressing. To develop a consistent level of safe practice, it is proposed that a minimum level of MRI-specific education is defined and mandated to practise. Continuing professional development focussing on MRI safety must be encouraged and, if audited as part of registration, could also be mandated. Implementation of a supporting regulatory framework similar to NZ is recommended for other countries. All MRI technologists are responsible for the safety of their patients and staff. Employers must support and ensure MRI-specific education has been completed. Ongoing engagement in MRI safety events provided by MRI safety experts, professional bodies and/or universities is essential to remain up-to-date. [ABSTRACT FROM AUTHOR]

Background Magnetic resonance imaging (MRI) safety screening is a crucial procedure for patient preparation before entering into MRI room. Many hospitals in Malaysia are still using the MRI safety checklist printed form. Besides, clinicians will not get a definite conclusion about whether the patient is contraindicated for MRI or not. Hence, we have created one mobile application named MagnetoSafe to overcome this issue. The application will provide an instant decision on whether the patient has no contraindication, relative contraindication, or absolute contraindicated for MRI. We need to check for acceptability and user experience for any newly created mobile application. Objective This study was designed to check the validity of the adapted Technology Acceptance Model (TAM) and System Usability Scale (SUS) Questionnaire. Method The validity and reliability of the questionnaire were investigated. Subsequently, 52 fully completed responses were collected. Results Face and content validity of the questionnaires are considered acceptable with only minor changes to Item 10 of SUS. The Cronbach's alpha for the SUS questionnaire (10 questions) is −0.49, which is not acceptable. The Cronbach's alpha for TAM questionnaire (3 domains; 14 questions) is acceptable, which is 0.910 for perceived usefulness, 0.843 for perceived ease of use, and 0.915 for intention to use. Conclusion Face validity of the adapted SUS and modified TAM questionnaires is acceptable with only minor changes to Item 10 in SUS. Content validity with experts is good. However, the reliability of the SUS questionnaire is not acceptable and therefore adapted SUS will not be used for assessing user experience. The reliability of the modified TAM questionnaire with the original three-factor structure is considered acceptable and can be used to evaluate the user's acceptability of MagnetoSafe.

MRI is the imaging modality of choice for assessing many pediatric medical conditions. Although there are several inherent potential safety risks associated with the electromagnetic fields exploited for MRI, they are effectively mitigated through strict adherence to established MRI safety practices, enabling the safe and effective use of MRI in clinical practice. The potential hazards of the MRI environment may be exacerbated by/in the presence of implanted medical devices. Awareness of the unique MRI safety and screening challenges associated with these implanted devices is critical to ensuring MRI safety for the affected patients. In this review article, we will discuss the basics of MRI physics as they relate to MRI safety in the presence of implanted medical devices, strategies for assessing children with known or suspected implanted medical devices, and the particular management of several well-established common, as well as recently developed, implanted devices encountered at our institution. [ABSTRACT FROM AUTHOR]

Purpose: To assess the accuracy of morphing an established reference electromagnetic head model to a subject‐specific morphometry for the estimation of specific absorption rate (SAR) in 7T parallel‐transmit (pTx) MRI. Methods: Synthetic T1‐weighted MR images were created from three high‐resolution open‐source electromagnetic head voxel models. The accuracy of morphing a "reference" (multimodal image‐based detailed anatomical [MIDA]) electromagnetic model into a different subject's native space (Duke and Ella) was compared. Both linear and nonlinear registration methods were evaluated. Maximum 10‐g averaged SAR was estimated for circularly polarized mode and for 5000 random RF shim sets in an eight‐channel transmit head coil, and comparison made between the morphed MIDA electromagnetic models and the native Duke and Ella electromagnetic models, respectively. Results: The averaged error in maximum 10‐g averaged SAR estimation across pTx MRI shim sets between the MIDA and the Duke target model was reduced from 17.5% with only rigid‐body registration, to 11.8% when affine linear registration was used, and further reduced to 10.7% when nonlinear registration was used. The corresponding figures for the Ella model were 16.7%, 11.2%, and 10.1%. Conclusion: We found that morphometry accounts for up to half of the subject‐specific differences in pTx SAR. Both linear and nonlinear morphing of an electromagnetic model into a target subject improved SAR agreement by better matching head size, morphometry, and position. However, differences remained, likely arising from details in tissue composition estimation. Thus, the uncertainty of the head morphometry and tissue composition may need to be considered separately to achieve personalized SAR estimation. [ABSTRACT FROM AUTHOR]

Adverse reactions in tattooed skin during magnetic resonance imaging (MRI) are rare but well known. Previous reports describe sudden burning pain in tattooed skin, sometimes accompanied by mild erythema and oedema when entering MRI scanners. The pathophysiology remains unclear, but simple direct thermal heating can be excluded. It has been hypothesized that MRI-triggered torque and traction create neural sensations from magnetic pigment particles. However, this case enlightens yet another possible mechanism. We present a 35-year-old woman experiencing reoccurring stinging sensations in three decorative black tattoos just seconds after the initiation of the MRI. Single-blind tests with handheld power magnets or a dummy could reproduce painful subjective feelings in her tattooed skin. Similar events were provoked during re-evaluation with MRI. Surprisingly, chemical analyses and electron microscopy of skin samples revealed carbon black as the colouring agent – no iron-based solids were detected. Our case demonstrates that MRI tattoo reactions are not limited to magnetic contaminants alone. More distinct subgroups of MRI-induced reactions may occur. We hypothesize that radiofrequency induction of surface currents in black carbon particles adjacent to sensory axons in the dermis may lead to neurosensations. [ABSTRACT FROM AUTHOR]

Background: An MRI is potentially hazardous for patients with retained ferromagnetic bullets. Recent studies have aimed to develop dual-energy computed tomography (DECT) as a screening tool for recognising highly ferromagnetic bullets. Inconsistent findings have been ascribed to inherent CT technology differences. Previous research demonstrated significant Hounsfield unit (HU) measurement variation among single-source CT machines. Objectives: This study investigated the theoretical dual-energy index (DEI) variation between DECT machines when evaluating the potential ferromagnetic properties within the same sample of ex vivo bullets and metal phantoms. Method: An experimental ex vivo study was conducted on eight metal phantoms and 10 unused bullets individually positioned in the same Perspex head phantom and scanned on two DECT machines. Two senior radiology registrars independently recorded the HU readings, and DEI values were calculated. Statistical analysis was performed using non-parametric methods for paired data, namely the Signed Rank Test. The DEI values based on mean HU readings between the DECT machines were compared. Results: Inter- and intra-reader agreement was not statistically significant. The metal phantoms had poor interscanner agreement, with an overlap of the ferromagnetic and non-ferromagnetic ranges. The bullets had good interscanner agreement, with a similar ferromagnetic to non-ferromagnetic relationship. Conclusion: The use of DEI values negates the previous assumption that significant interscanner variability exists among different DECT technologies while assessing highly attenuative ex vivo bullets. Contribution: This investigation demonstrated that even though HU readings may be variable, the implementation of the DEI equation translates this into comparable values with good interscanner agreement.

Background Magnetic resonance imaging (MRI) safety screening is a crucial procedure for patient preparation before entering into MRI room. Many hospitals in Malaysia are still using the MRI safety checklist printed form. Besides, clinicians will not get a definite conclusion about whether the patient is contraindicated for MRI or not. Hence, we have created one mobile application named MagnetoSafe to overcome this issue. The application will provide an instant decision on whether the patient has no contraindication, relative contraindication, or absolute contraindicated for MRI. We need to check for acceptability and user experience for any newly created mobile application. Objective This study was designed to check the validity of the adapted Technology Acceptance Model (TAM) and System Usability Scale (SUS) Questionnaire. Method The validity and reliability of the questionnaire were investigated. Subsequently, 52 fully completed responses were collected. Results Face and content validity of the questionnaires are considered acceptable with only minor changes to Item 10 of SUS. The Cronbach's alpha for the SUS questionnaire (10 questions) is −0.49, which is not acceptable. The Cronbach's alpha for TAM questionnaire (3 domains; 14 questions) is acceptable, which is 0.910 for perceived usefulness, 0.843 for perceived ease of use, and 0.915 for intention to use. Conclusion Face validity of the adapted SUS and modified TAM questionnaires is acceptable with only minor changes to Item 10 in SUS. Content validity with experts is good. However, the reliability of the SUS questionnaire is not acceptable and therefore adapted SUS will not be used for assessing user experience. The reliability of the modified TAM questionnaire with the original three-factor structure is considered acceptable and can be used to evaluate the user's acceptability of MagnetoSafe. [ABSTRACT FROM AUTHOR]

Purpose: We describe a clinical grade, "active", monopole antenna‐based metallic guidewire that has a continuous shaft‐to‐tip image profile, a pre‐shaped tip‐curve, standard 0.89 mm (0.035″) outer diameter, and a detachable connector for catheter exchange during cardiovascular catheterization at 0.55T. Methods: Electromagnetic simulations were performed to characterize the magnetic field around the antenna whip for continuous tip visibility. The active guidewire was manufactured using medical grade materials in an ISO Class 7 cleanroom. RF‐induced heating of the active guidewire prototype was tested in one gel phantom per ASTM 2182‐19a, alone and in tandem with clinical metal‐braided catheters. Real‐time MRI visibility was tested in one gel phantom and in‐vivo in two swine. Mechanical performance was compared with commercial equivalents. Results: The active guidewire provided continuous "profile" shaft and tip visibility in‐vitro and in‐vivo, analogous to guidewire shaft‐and‐tip profiles under X‐ray. The MRI signal signature matched simulation results. Maximum unscaled RF‐induced temperature rise was 5.2°C and 6.5°C (3.47 W/kg local background specific absorption rate), alone and in tandem with a steel‐braided catheter, respectively. Mechanical characteristics matched commercial comparator guidewires. Conclusion: The active guidewire was clearly visible via real‐time MRI at 0.55T and exhibits a favorable geometric sensitivity profile depicting the guidewire continuously from shaft‐to‐tip including a unique curved‐tip signature. RF‐induced heating is clinically acceptable. This design allows safe device navigation through luminal structures and heart chambers. The detachable connector allows delivery and exchange of cardiovascular catheters while maintaining guidewire position. This enhanced guidewire design affords the expected performance of X‐ray guidewires during human MRI catheterization. [ABSTRACT FROM AUTHOR]

Transcatheter closure of septal defects using specialized devices is a common procedure that has a high success rate. Embolization of Atrial septal defect devices is a known complication seen at a rate of 0.5%. We report a case of late ASD device occluder embolization immediately after brain MRI with clinical consequences and intraoperative evidence of right atrial wall thermal injury. To our knowledge Atrial septal occluder (ASO) device embolization post magnetic resonance imaging (MRI) was not reported before, although theoretically possible and that's why six to eight weeks post device implantation MRI is prohibited even with current MRI compatible devices. [ABSTRACT FROM AUTHOR]

Background: An MRI is potentially hazardous for patients with retained ferromagnetic bullets. Recent studies have aimed to develop dual-energy computed tomography (DECT) as a screening tool for recognising highly ferromagnetic bullets. Inconsistent findings have been ascribed to inherent CT technology differences. Previous research demonstrated significant Hounsfield unit (HU) measurement variation among single-source CT machines. Objectives: This study investigated the theoretical dual-energy index (DEI) variation between DECT machines when evaluating the potential ferromagnetic properties within the same sample of ex vivo bullets and metal phantoms. Method: An experimental ex vivo study was conducted on eight metal phantoms and 10 unused bullets individually positioned in the same Perspex head phantom and scanned on two DECT machines. Two senior radiology registrars independently recorded the HU readings, and DEI values were calculated. Statistical analysis was performed using non-parametric methods for paired data, namely the Signed Rank Test. The DEI values based on mean HU readings between the DECT machines were compared. Results: Inter- and intra-reader agreement was not statistically significant. The metal phantoms had poor interscanner agreement, with an overlap of the ferromagnetic and non-ferromagnetic ranges. The bullets had good interscanner agreement, with a similar ferromagnetic to nonferromagnetic relationship. Conclusion: The use of DEI values negates the previous assumption that significant interscanner variability exists among different DECT technologies while assessing highly attenuative ex vivo bullets. Contribution: This investigation demonstrated that even though HU readings may be variable, the implementation of the DEI equation translates this into comparable values with good interscanner agreement. [ABSTRACT FROM AUTHOR]

• Imaging with a DBS electrode inductively coupled to a toroidal transceiver. • Reduced RF artifact, scan time and improved SNR near the DBS electrode. • Accurate heating prediction at DBS contacts in vivo and postmortem in swine brain. • Preliminary imaging results in postmortem swine brain with the toroidal transceiver. Magnetic resonance imaging (MRI) provides excellent soft tissue contrast for visualizing of deep brain stimulation (DBS) targets, allowing validation of the electrode placement, and assessing complications such as microhemorrhage and edema. However, the presence of the electrodes can introduce challenges such as radiofrequency (RF) induced current artifacts and excessive heating of the electrode contacts. Additionally, extended procedure times are also considered a disadvantage when using MRI as an intraoperative imaging modality following DBS electrode placement. We propose a novel approach of using toroidal resonators to inductively couple the shaft of the electrode to the scanner's transmit-receive chain thereby utilizing it as a localized imaging antenna. The small extent of the field generated by the electrode antenna allows fast imaging with smaller field-of-views (FOVs) spanning only a few centimeters. Furthermore, we present a fast and accurate safety monitoring strategy that can be used to predict the temperature increase at the electrical contacts of the electrode. Imaging with the toroidal transceiver yields a higher signal-to-noise ratio (SNR) efficiency in proximity to the electrodes. This approach reduced the RF induced current artifacts around the electrode which enhanced the visibility of the shaft and improved electrode localization. Moreover, the limited sensitivity around the electrode can be exploited to perform fast scans with small FOVs. The predicted heating around DBS contacts was in quantitative agreement with the experimental heating in swine studies with a normalized root-mean-square error (NRMSE) ≤ 0.09. [ABSTRACT FROM AUTHOR]

Percutaneous peripheral nerve stimulation (PNS) is an FDA-cleared pain treatment. Occasionally, fragments of the lead (MicroLead, SPR Therapeutics, LLC, Cleveland, OH, USA) may be retained following lead removal. Since the lead is metallic, there are associated magnetic resonance imaging (MRI) risks. Therefore, the objective of this investigation was to evaluate MRI-related issues (i.e., magnetic field interactions, heating, and artifacts) for various lead fragments.Testing was conducted using standardized techniques on lead fragments of different lengths (i.e., 50, 75, and 100% of maximum possible fragment length of 12.7 cm) to determine MRI-related problems. Magnetic field interactions (i.e., translational attraction and torque) and artifacts were tested for the longest lead fragment at 3 Tesla. MRI-related heating was evaluated at 1.5 Tesla/64 MHz and 3 Tesla/128 MHz with each lead fragment placed in a gelled-saline filled phantom. Temperatures were recorded on the lead fragments while using relatively high RF power levels. Artifacts were evaluated using T1-weighted, spin echo, and gradient echo (GRE) pulse sequences.The longest lead fragment produced only minor magnetic field interactions. For the lead fragments evaluated, physiologically inconsequential MRI-related heating occurred at 1.5 Tesla/64 MHz while under certain 3 Tesla/128 MHz conditions, excessive temperature elevations may occur. Artifacts extended approximately 7 mm from the lead fragment on the GRE pulse sequence, suggesting that anatomy located at a position greater than this distance may be visualized on MRI.MRI may be performed safely in patients with retained lead fragments at 1.5 Tesla using the specific conditions of this study (i.e., MR Conditional). Due to possible excessive temperature rises at 3 Tesla, performing MRI at that field strength is currently inadvisable.

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This study shows how inter-subject variation over a dataset of 72 head models results in specific absorption rate (SAR) and B 1 + field homogeneity differences using common shim scenarios. MR-CT datasets were used to segment 71 head models into 10 tissue compartments. These head models were affixed to the shoulders and neck of the virtual family Duke model and placed within an 8 channel transmit surface-loop array to simulate the electromagnetic fields of a 7T imaging experiment. Radio frequency (RF) shimming using the Gerchberg-Saxton algorithm and Circularly Polarized shim weights over the entire brain and select slices of each model was simulated. Various SAR metrics and B 1 + maps were calculated to demonstrate the contribution of head variation to transmit inhomogeneity and SAR variability. With varying head geometries the loading for each transmit loop changes as evidenced by changes in S-parameters. The varying shim conditions and head geometries are shown to affect excitation uniformity, spatial distributions of local SAR, and SAR averaging over different pulse sequences. The Gerchberg-Saxton RF shimming algorithm outperforms circularly polarized shimming for all head models. Peak local SAR within the coil most often occurs nearest the coil on the periphery of the body. Shim conditions vary the spatial distribution of SAR. The work gives further support to the need for fast and more subject specific SAR calculations to maintain safety. Local SAR 10g is shown to vary spatially given shim conditions, subject geometry and composition, and position within the coil. • 7T decoupled coil array transmit metrics simulated for 72 head models. • RF coil traces within 2 cm of the subject may exceed tissue heating limits. • Non-linear RF shimming over a population outperforms circularly polarized shims. • Average tissue heating rates differ for each patient depending on the sequence. [ABSTRACT FROM AUTHOR]

Near field communication (NFC) is a wireless, short-range, secure communication technology that may be used for healthcare-related applications. An NFC device was recently developed that was intended for implantation in the dorsal fascia, above the interosseous compartment of the hand. This implant uses a ferrite rod to increase the distance of communication between devices. The purpose of this investigation was to evaluate MRI issues for this NFC device using standardized techniques and well-accepted methodology. The NFC device (Vivokey Spark 2, Cryptobionic Implant, Vivokey Technologies, www.vivokey.com) was assessed for magnetic field interactions (force and torque) at 3-Tesla, magnetic field interactions according to the simulated intended use of the implant, MRI-related heating at 1.5-Tesla/64-MHz and 3-Tesla/128-MHz, functional change associated with MRI conditions at 1.5-Tesla/64-MHz and 3-Tesla/128-MHz, and artifacts at 3-Tesla. The mean deflection angle was 90° ± 0 and torque was "positive". However, tests evaluating the simulated intended use of the NFC device demonstrated no movement, displacement, or rotational alignment. The highest temperature changes at 1.5-Tesla/64-MHz and 3-Tesla/128-MHz were 1.7 °C and 1.9 °C, respectively. There was no change in the operational capabilities of the NFC device related to the MRI exposures. Artifacts were relatively large in comparison to the size of the NFC device. The findings indicated that the particular NFC device that underwent evaluation is "MR Conditional" for a patient undergoing MRI at 1.5-Tesla or 3-Tesla, operating the scanner in the Normal Operating Mode (i.e., default whole-body averaged SAR of 2.0-W/kg). Notably, this is the first NFC device evaluated for MRI-related issues. • Near field communication (NFC) is a wireless communication technology that can be used for various healthcare-related applications. • An NFC device was developed with a ferrite core, thus, there are MRI-related safety issues. • An NFC device was developed with a ferrite core, thus, there are MRI-related safety issues. • This NFC device will not pose a risk to a patient undergoing MRI at 1.5- or 3-Tesla and, therefore, it is MR Conditional. [ABSTRACT FROM AUTHOR]

Background: Testing MRI gradient‐induced heating of implanted medical devices is required by regulatory organizations and others. A gradient heating test of the ISO 10974 Technical Specification (TS) for active implants was adopted for this study of passive hip implants. All but one previous study of hip implants used nonuniform gradient exposure fields in clinical scanners and reported heating of less than 5 °C. This present study adapted methods of the TS, addressing the unmet need for identifying worst‐case heating via exposures to uniform gradient fields. Purpose: To identify gradient‐field parameters affecting maximum heating in vitro for a hip implant and a cylindrical titanium disk. Study Type: Computational simulations and experimental validation of induced heating. Phantom: Tissue‐simulating gel. Field Strength: 42 T/s RMS, sinusoidal, continuous B fields with high spatial uniformity Assessment: Hip implant heating at 1–10 kHz, via computational modeling, validated by limited point measurements. Experimental measurements of exposures of an implant at 42 T/s for 4, 6, and 9 kHz, analyzed at 50, 100, and 150 seconds. Statistical Tests: One sample student's t‐test to assess difference between computational and experimental results. Experimental vs. computational results were not significantly different (p < 0.05). Results: Maximum simulated temperature rise (10‐minute exposure) was 10 °C at 1 kHz and 0.66 °C at 10 kHz. The ratio of the rise for 21 T/s vs. 42 T/s RMS was 4, after stabilizing at 50 seconds (dB/dt ratio squared). Data Conclusions: Heating of an implant is proportional to the frequency of the B field and the implant's cross‐sectional area and is greater for a thickness on the order of its skin depth. Testing with lower values of dB/dt RMS with lower cost amplifiers enables prediction of heating at higher values for dB/dt squared (per ISO TS) with identical frequency components and waveforms, once thermal equilibrium occurs. Evidence Level: 1 Technical Efficacy: Stage 1 [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study is to prospectively evaluate whether women with copper-containing intrauterine devices (Cu-IUD), currently listed as MR conditional, can safely undergo 3.0 Tesla (3 T) magnetic resonance imaging (MRI)., Methods: 73 women, age 18-54 years old, with a Cu-IUD who were undergoing MRI for any reason were included consecutively. Pre- and post-MRI standard pelvic ultrasound examinations were completed to determine the appropriate pre- and post-MRI positioning of the Cu-IUD. Displaced IUDs were defined by IUD crossbars not in the fundal portion of the endometrial cavity, a visualized tip in the mid or lower uterus, any part of the device located in the cervical canal or outside of the endometrial canal, a fractured device, or a non-visualized IUD. Additionally, a questionnaire was completed by participants to determine the level of pre- and post-MRI pelvic pain., Results: There were zero observed displaced Cu-IUDs on post-MRI pelvic ultrasounds (p = 0/70, 95% CI 0, .043). Three participants were dropped from the study due to malpositioned IUDs on pre-MRI pelvic ultrasound. Six patients reported new or worsening pelvic pain/discomfort during or after their MRI examination., Conclusion: Our results suggest that performing 3 T MRI using a low SAR setting does not cause displacement of Cu-IUDs, with zero out of 70 patients demonstrating IUD displacement., (© 2024. The Author(s).)

Purpose: To develop and test an MRI coil assembly for imaging deep brain stimulation (DBS) at 3 T with a reduced level of local specific absorption rate of RF fields near the implant., Methods: A mechanical rotatable linearly polarized birdcage transmitter outfitted with a 32-channel receive array was constructed. The coil performance and image quality were systematically evaluated using bench-level measurements and imaging performance tests, including SNR maps, array element noise correlation, and acceleration capabilities. Electromagnetic simulations and phantom experiments were performed with clinically relevant DBS device configurations to evaluate the reduction of specific absorption rate and temperature near the implant compared with a circular polarized body coil setup., Results: The linearly polarized birdcage coil features a block-shaped low electric field region to be co-aligned with the implanted DBS lead trajectory, while the close-fit receive array enables imaging with high SNR and enhanced encoding capabilities., Conclusion: The 3T coil assembly, consisting of a rotating linear birdcage and a 32-channel close-fit receive array, showed DBS-conditioned imaging technology with substantially reduced heat generation at the DBS implants., (© 2024 The Author(s). Magnetic Resonance in Medicine published by Wiley Periodicals LLC on behalf of International Society for Magnetic Resonance in Medicine.)