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The "5 gauss line" is a phrase that is likely to be familiar to everyone working with MRI, but what is its significance, how was it defined, and what changes are currently in progress? This review explores the history of 5 gauss (0.5 mT) as a threshold for protecting against inadvertently putting cardiac pacemakers, implantable cardioverter defibrillators, and other active implantable medical devices into a "magnet mode." Additionally, it describes the background to the recent change of this threshold to 9 gauss (0.9 mT) in the International Standard IEC 60601‐2‐33 edition 4.0 that defines basic safety requirements for MRI. Practical implications of this change and some ongoing and emerging issues are also discussed. [ABSTRACT FROM AUTHOR]

Purpose: To study implant lead tip heating because of the RF power deposition by developing mathematical models and comparing them with measurements acquired at 1.5 T and 3 T, especially to predict resonant length. Theory and Methods: A simple exponential model and an adapted transmission line model for the electric field transfer function were developed. A set of wavenumbers, including that calculated from insulated antenna theory (King wavenumber) and that of the embedding medium were considered. Experiments on insulated, capped wires of varying lengths were performed to determine maximum temperature rise under RF exposure. The results are compared with model predictions from analytical expressions derived under the assumption of a constant electric field, and with those numerically calculated from spatially varying, simulated electric fields from body coil transmission. Simple expressions for the resonant length bounded between one‐quarter and one‐half wavelength are developed based on the roots of transcendental equations. Results: The King wavenumber for both models more closely matched the experimental data with a maximum root mean square error of 9.81°C at 1.5 T and 5.71°C at 3 T compared to other wavenumbers with a maximum root mean square error of 27.52°C at 1.5 T and 22.01°C for 3 T. Resonant length was more accurately predicted compared to values solely based on the embedding medium. Conclusion: Analytical expressions were developed for implanted lead heating and resonant lengths under specific assumptions. The value of the wavenumber has a strong effect on the model predictions. Our work could be used to better manage implanted device lead tip heating. [ABSTRACT FROM AUTHOR]

Abstract Objectives Despite the absence of ionizing radiation, magnetic resonance (MR) has inherent risks in clinical practice that can have serious health consequences if overlooked. At an international level, there are MR safety guidelines that help define the organization of a radiology department to minimize the risks for patients and personnel. However, competing guidelines exist and not every country and institution adheres to the same standards. In this work, we aim to understand the current situation regarding MR safety practices across Europe, and to identify the points where harmonization, coordination, or further education is needed. Methods An anonymous survey questionnaire was distributed between April and June 2023 through ESR member societies to healthcare professionals, aimed to assess personnel training, local policies, scanning practices, and accidents. Results Seven hundred and ninety-three responses were obtained from 44 different countries. The majority of respondents from five countries reported that MR safety is mandated by law, but we could only confirm two (Italy and Austria). While 77% of the responses said that their institution had a clear MR safety guideline, 52% said that nobody in their institution had received specific MR safety training. MR-conditional cardiac devices are mostly scanned in university hospitals (reported by 75% of respondents from this type of institution) but in only 42% of outpatient facilities. MR-unsafe cardiac devices are only scanned off-label in 27% of university hospitals, and in an even smaller share of other institutions. Approximately 12% of the respondents reported MR-related accidents resulting in patient or personnel injury. Overall, there is the sentiment that MR safety education and regulation are needed. Conclusions The European landscape in terms of MR safety is very heterogeneous, with different regulations across countries, and different procedures for MR safety training and their application in clinical routine. The European Society of Radiology is optimally positioned to play an active role in the harmonization of MR safety education and practices across Europe, and we are proposing a four-tiered framework for the development of a teaching curriculum for MR safety training. Critical relevance statement There is room for raising awareness of MR safety issues to ensure patient safety, reduce accidents, and benefit more patients. We advocate for radiologist-led standardization and improvement of MR safety training as a way to address this problem. Key Points Our survey of MR safety practices across Europe revealed significant heterogeneity in regulations, training, and scanning practices. There is a widespread lack of awareness and implementation of MR safety guidelines and diffuse uncertainty, under-scanning of eligible patients, and preventable accidents. The ESR proposes a harmonized, four-tiered MR safety training curriculum to standardize, and improve safety practices across Europe.

Use of magnetic resonance (MR) imaging in radiation therapy has increased substantially in recent years as more radiotherapy centers are having MR simulators installed, requesting more time on clinical diagnostic MR systems, or even treating with combination MR linear accelerator (MR‐linac) systems. With this increased use, to ensure the most accurate integration of images into radiotherapy (RT), RT immobilization devices and accessories must be able to be used safely in the MR environment and produce minimal perturbations. The determination of the safety profile and considerations often falls to the medical physicist or other support staff members who at a minimum should be a Level 2 personnel as per the ACR. The purpose of this guidance document will be to help guide the user in making determinations on MR Safety labeling (i.e., MR Safe, Conditional, or Unsafe) including standard testing, and verification of image quality, when using RT immobilization devices and accessories in an MR environment. [ABSTRACT FROM AUTHOR]

Background: The imaging of patients with implanted electrically‐conductive devices via magnetic resonance imaging at ultra‐high fields is hampered by uncertainties relating to the potential for inducing tissue heating adjacent to the implant due to coupling of energy from the incident electromagnetic field into the implant. Existing data in the peer‐reviewed literature of comparisons across field strengths of tissue heating and its surrogate, the specific absorption rate (SAR), is scarce and contradictory, leading to further doubts pertaining to the safety of imaging patients with such devices. Purpose: The radiofrequency‐induced SAR adjacent to orthopedic screws of varying length and at frequencies of 64 to 498 MHz was investigated via full‐wave electromagnetic simulations, to provide an accurate comparison of SAR across MRI field strengths. Methods: Dipole antennas were used for RF transmission to achieve a uniform electric field tangential to the screws located 120 mm above the antenna midpoints, embedded in a bone‐mimicking material. The input power to the antennas was constrained to achieve the following targets without the screw present: (i) E = 100 V/m, (ii) B1+ = 2 μT, and (iii) global‐average‐SAR = 3.2 W/kg. Simulations were performed with a spatial resolution of 0.2 mm in the volume surrounding the screws, resulting in 76–137 MCells, noting the maximum 1 g‐averaged SAR value in each case. Simulations were repeated at 128 and 297 MHz for screws embedded in muscle tissue. Results: The peak SAR, occurring at the resonant screw length, substantially increased as the frequency decreased when the input power to the dipole antenna was constrained to achieve constant electric field in background tissue at the screws' locations. A similar pattern was observed when constraining input power to achieve constant B1+ and global‐average‐SAR. The dielectric properties of the tissue in which the screws were embedded dominated the SAR comparisons between 297 and 128 MHz. Conclusions: The study design allowed for a direct comparison to be performed of SAR across frequencies and implant lengths without the confounding effect of variable incident electric field. Lower frequencies produced substantially larger SAR values for implants approaching the resonant length for the worst‐case uniform incident electric field along the screws' length. The data may inform risk‐benefit assessments for imaging patients with orthopedic implants at the new clinical field strength of 7 Tesla. [ABSTRACT FROM AUTHOR]

Purpose: Radiofrequency (RF) exposure during MR examination is limited by IEC 60601‐2‐33 to prevent thermal hazards to patients. These limits are also the basis to derive the maximum induced field for the demonstration of MR safety of implants per ISO/TS 10974 (2018). One limit is the head‐averaged specific absorption rate (SAR), for which the head extent is defined differently by MR and implant vendors. The purpose of this technical note is to inform MR safety stakeholders on the sensitivity of safety evaluations due to different head extent definitions. Methods: RF distributions from the validated MRIxViP exposure libraries of 12 high‐resolution human anatomical models were scaled to the normative SAR limits for different definitions of the head extent to compare the corresponding induced SAR and electric (E‐)field levels. Results: The definitions of the head extent used by major implant vendors and defined in ISO/TS 10974 (2018) are larger than those introduced in IEC 60601‐2‐33 (2022), resulting in lower RF head exposure by up to 2.4 dB (factor 1.7). Other proposed definitions of the head result in intermediate values. Conclusion: The different head extents result in different maximum RF exposures affecting the risk assessment by up to a factor of 1.7. The results of this study can be used to estimate the additional uncertainty in safety assessments. Future revisions of MR standards should eliminate this inconsistency. [ABSTRACT FROM AUTHOR]

Purpose: To investigate a novel reduced RF heating method for imaging in the presence of active implanted medical devices (AIMDs) which employs a sensor‐equipped implant that provides wireless feedback. Methods: The implant, consisting of a generator case and a lead, measures RF‐induced E$$ E $$‐fields at the implant tip using a simple sensor in the generator case and transmits these values wirelessly to the MR scanner. Based on the sensor signal alone, parallel transmission (pTx) excitation vectors were calculated to suppress tip heating and maintain image quality. A sensor‐based imaging metric was introduced to assess the image quality. The methodology was studied at 7T in testbed experiments, and at a 3T scanner in an ASTM phantom containing AIMDs instrumented with six realistic deep brain stimulation (DBS) lead configurations adapted from patients. Results: The implant successfully measured RF‐induced E$$ E $$‐fields (Pearson correlation coefficient squared [R2] = 0.93) and temperature rises (R2 = 0.95) at the implant tip. The implant acquired the relevant data needed to calculate the pTx excitation vectors and transmitted them wirelessly to the MR scanner within a single shot RF sequence (<60 ms). Temperature rises for six realistic DBS lead configurations were reduced to 0.03–0.14 K for heating suppression modes compared to 0.52–3.33 K for the worst‐case heating, while imaging quality remained comparable (five of six lead imaging scores were ≥0.80/1.00) to conventional circular polarization (CP) images. Conclusion: Implants with sensors that can communicate with an MR scanner can substantially improve safety for patients in a fast and automated manner, easing the current burden for MR personnel. [ABSTRACT FROM AUTHOR]

The purpose of this research is to more precisely quantify the positivity rate for conventional radiographs (CR) of the orbit performed for the purpose of pre-MR screening in patients at risk of having a radio-opaque orbital foreign body (ROFB). By review of electronic medical records, we identified 47,237 patients who had undergone orbital CR for clearance of ROFB prior to MRI. The reports from these examinations were manually reviewed, and the examinations with positive findings were re-interpreted by a CAQ-certified head and neck radiologist. The rate of ROFB found in these examinations was reported and compared to historical estimates in the literature. 328 of the 47,237 examinations (0.69 %) were originally interpreted as positive for ROFB. Upon re-review, only 39 of the 47,237 examinations (0.083 %, 95 % CI 0.06 %-0.11 %) contained ROFB that were in locations that posed a risk to ocular or vascular structures or were in an equivocal location. Almost all of the patients with false-positive initial interpretations had been denied MRI. The rate of ROFB discovered on clearance CR of the orbits prior to MRI is far less than previously estimated in the radiology literature. More conservative guidelines for MR clearance may be useful to reduce costs, mitigate imaging delays, and avoid unnecessary denial of imaging. [ABSTRACT FROM AUTHOR]

Cardiovascular magnetic resonance (CMR) is a proven imaging modality for informing diagnosis and prognosis, guiding therapeutic decisions, and risk stratifying surgical intervention. Patients with a cardiac implantable electronic device (CIED) would be expected to derive particular benefit from CMR given high prevalence of cardiomyopathy and arrhythmia. While several guidelines have been published over the last 16 years, it is important to recognize that both the CIED and CMR technologies, as well as our knowledge in MR safety, have evolved rapidly during that period. Given increasing utilization of CIED over the past decades, there is an unmet need to establish a consensus statement that integrates latest evidence concerning MR safety and CIED and CMR technologies. While experienced centers currently perform CMR in CIED patients, broad availability of CMR in this population is lacking, partially due to limited availability of resources for programming devices and appropriate monitoring, but also related to knowledge gaps regarding the risk-benefit ratio of CMR in this growing population. To address the knowledge gaps, this SCMR Expert Consensus Statement integrates consensus guidelines, primary data, and opinions from experts across disparate fields towards the shared goal of informing evidenced-based decision-making regarding the risk-benefit ratio of CMR for patients with CIEDs.

Access to high-quality MR exams is severely limited for patients with some implanted devices due to labeled MR safety conditions, but small-bore systems can overcome this limitation. For example, a compact 3 T MR scanner (C3T) with high-performance gradients can acquire exams of the head, extremities, and infants. Because of its reduced bore size and the patient being advanced only partially into the bore, the associated electromagnetic (EM) fields drop off rapidly caudal to the head, compared to whole-body systems. Therefore, some patients with MR conditional implanted devices can safely receive 3 T brain exams on the C3T using its strong gradients and a multiple-channel receive coil, while a corresponding exam on whole-body MR is precluded. The purpose of this study is to evaluate the performance of a small-bore scanner for subjects with MR conditional spinal or sacral nerve stimulators, or abandoned cardiac implantable electronic device (CIED) leads. The spatial dependence of specific absorption rate (SAR) on the C3T was compared to whole-body scanners. A device assessment tool was developed and applied to evaluate MR safety individually on the C3T for 12 subjects with implanted devices or abandoned CIED leads. Once MR safety was established, the subjects received a C3T brain exam along with their clinical, 1.5 T exam. The resulting images were graded by three board-certified neuroradiologists. The C3T exams were well-tolerated with no adverse events, and significantly outperformed the whole-body 1.5 T exams in terms of overall image quality. • Small-bore systems offer significant advantages for subjects with devices. • A compact 3T system has reduced head and body SAR compared to whole body 3T. • Devices limited to 1.5T can be safely scanned on compact 3 T with improved IQ. [ABSTRACT FROM AUTHOR]

IntroductionQuantitative sensory testing (QST) is often used to understand the perceptual basis of acute and chronic conditions, including pain. As the need grows for developing a mechanistic understanding of neurological pathways underlying perception in the basic and clinical sciences, there is a greater need to adapt techniques such as QST to the magnetic resonance (MR) environment. No studies have yet evaluated the impact of the MR environment on the perception of thermal stimuli. This study aimed to evaluate the differences in temperature sensitivity outside an MR environment and during an MRI scanning session. We hypothesized that there would be a difference in how participants reported their pain sensitivity between the two environments.MethodsHealthy participants underwent thermal QST outside the MR scanning environment, where they were asked to rate the temperature of a noxious stimulus at which they perceived their pain to be 7/10, using a Likert scale ranging from 0 to 10. Participants repeated this procedure inside a 3.0 T MRI approximately 30 min later. We repeated our investigation in a clinical cohort of participants with a chronic pain condition.ResultsThere were statistically significant changes of 1.1°C in thermal sensitivity between environments. This increase in pain threshold was found in healthy participants and replicated in the clinical cohort.DiscussionFindings can be applied toward improving MR safety, the resolution of brain pathways underlying pain mechanisms, and to more broadly comment on the impact of the MR environment on investigations that integrate perception-influenced processes.

Purpose: The Radiofrequency (RF)‐induced heating for an active implantable medical device (AIMD) with dual parallel leads is evaluated in this paper. The coupling effects between dual parallel leads are studied via simulations and experiments methods. The global transfer function technique is used to assess the RF‐induced heating for dual‐lead AIMDs inside four human body models. Methods: RF‐induced heating for spinal cord stimulator systems with 60 and 90 cm length leads are studied at three parallel dual‐lead configurations (closely spaced, 8 mm spaced, and 40 mm spaced) and a single‐lead configuration. The global transfer function method is used to develop the AIMD models of different configurations and is used for lead‐tip heating assessments inside human body models. Results: In simulation studies, the peak 1g specific absorption rate/temperatrue rises of dual parallel leads systems is lower than those from the single‐lead system. In experimental American Society for Testing and Materials phantom studies, the temperature rises for the single‐lead AIMD system can be 2.4 times higher than that from dual‐lead AIMD systems. For the spinal cord stimulator systems used in the study, the statistical analysis shows the RF‐induced heating of dual‐lead configurations are also lower than those from the single‐lead configuration inside all four human body models. Conclusion: For the AIMD system in this study, it shows that the coupling effects between the dual parallel leads of AIMD systems can reduce RF‐induced heating. The global transfer function for different spatial distance dual‐lead configurations can potentially provide a method for the RF‐induced heating evaluation for dual‐lead AIMD systems. [ABSTRACT FROM AUTHOR]

Objective: Low-field MRI systems are expected to cause less RF heating in conventional interventional devices due to lower Larmor frequency. We systematically evaluate RF-induced heating of commonly used intravascular devices at the Larmor frequency of a 0.55 T system (23.66 MHz) with a focus on the effect of patient size, target organ, and device position on maximum temperature rise. Materials and methods: To assess RF-induced heating, high-resolution measurements of the electric field, temperature, and transfer function were combined. Realistic device trajectories were derived from vascular models to evaluate the variation of the temperature increase as a function of the device trajectory. At a low-field RF test bench, the effects of patient size and positioning, target organ (liver and heart) and body coil type were measured for six commonly used interventional devices (two guidewires, two catheters, an applicator and a biopsy needle). Results: Electric field mapping shows that the hotspots are not necessarily localized at the device tip. Of all procedures, the liver catheterizations showed the lowest heating, and a modification of the transmit body coil could further reduce the temperature increase. For common commercial needles no significant heating was measured at the needle tip. Comparable local SAR values were found in the temperature measurements and the TF-based calculations. Conclusion: At low fields, interventions with shorter insertion lengths such as hepatic catheterizations result in less RF-induced heating than coronary interventions. The maximum temperature increase depends on body coil design. [ABSTRACT FROM AUTHOR]

Key points 1. Technical and procedural compliance with CI guidelines does not necessarily ensure safe examination. 2. High proportion of severe and mild complications for non-cranial examinations. 3. Need for extended informed consent for patients with CI. 4. Indications for MRI examinations with CI should still be handled with care.

Objectives: The aim was to assess the type, frequency and impact of MRI-related complications in patients with cochlear implants (CI) and MRI indications in different body regions. Methods: For that purpose, the institutional radiology database of a single tertiary hospital was searched for patients with a CI who underwent MRI between 2001 and 2018. The number of MRI examinations and complications were retrieved from the patient record. Examinations were categorized into five distinct body regions or combinations thereof. Records of CI artifacts in the head also included basic information on diagnostic image quality. Results: Out of 1017 MRI database entries (examinations) of patients with a CI, 91 records were after implantation (71 patients) and 66 were attempted (no contraindications, 49 patients). In four cases (4/66, 6.1%), the magnet was dislocated and had to be replaced surgically. Three out of four severe complications occurred for examination regions outside the head. Thirteen MRI examinations were aborted due to pain (19.7%) and one because of artifacts—resulting in 48 scans (72.7%) completed successfully (36 patients). All cranial scans featured device artifacts in all sequences, but the majority of them did not affect proper imaging diagnostics in the respective region. Conclusion: This retrospective, single-center analysis of patients with MRI-conditional cochlear implants shows that MRI-related complications were common, at least in models with a fixed magnet, despite appropriate precautions and compliance with the manufacturers' guidelines. MRI examinations of CI patients should therefore be indicated strictly until the exact causes have been clarified. Key points: Technical and procedural compliance with CI guidelines does not necessarily ensure safe examination. High proportion of severe and mild complications for non-cranial examinations. Need for extended informed consent for patients with CI. Indications for MRI examinations with CI should still be handled with care. [ABSTRACT FROM AUTHOR]

Introduction: Magnetic Resonance (MR) safety is critically important in any Radiology Department, and MR-related accidents are preventable. Serious games provide opportunities for learners to build MR safety awareness through play in an immersive learning environment by using simulated scenarios such as screening virtual patients and managing an MR-related accident. Methods: We developed a serious game, in partnership with a game developer, introducing MR safety concepts to learners as they navigate through a virtual 3D Radiology department. Drag-and-drop minigames are incorporated to aid the learner to identify hazards in and around the MR environment. Virtual patients are placed in waiting areas to provide realism, and learners are tasked to screen them as part of MR Safety Screening checks. A simulation of an MR-related accident prompts learners to make decisions or take actions to ensure safety and mitigate further risks during the accident. The learner also role-plays as a Risk Officer to identify the multiple key incidents that led to the accident. These formative assessments, with instantaneous feedback, assesses the learners' knowledge of MR safety. Results: Pilot feedback of this serious game revealed that it is realistic, engaging and relatable. The instructions within the game were clear and aided learning. The game has also been scaled up and customised for the radiology departments of 3 other healthcare institutions. Conclusion: Serious games provide a training solution to raise MR safety awareness by simulating real-life scenarios in an immersive learning environment. It supplements face-to-face training and is scalable to other healthcare institutions.

Objectives: Despite the absence of ionizing radiation, magnetic resonance (MR) has inherent risks in clinical practice that can have serious health consequences if overlooked. At an international level, there are MR safety guidelines that help define the organization of a radiology department to minimize the risks for patients and personnel. However, competing guidelines exist and not every country and institution adheres to the same standards. In this work, we aim to understand the current situation regarding MR safety practices across Europe, and to identify the points where harmonization, coordination, or further education is needed., Methods: An anonymous survey questionnaire was distributed between April and June 2023 through ESR member societies to healthcare professionals, aimed to assess personnel training, local policies, scanning practices, and accidents., Results: Seven hundred and ninety-three responses were obtained from 44 different countries. The majority of respondents from five countries reported that MR safety is mandated by law, but we could only confirm two (Italy and Austria). While 77% of the responses said that their institution had a clear MR safety guideline, 52% said that nobody in their institution had received specific MR safety training. MR-conditional cardiac devices are mostly scanned in university hospitals (reported by 75% of respondents from this type of institution) but in only 42% of outpatient facilities. MR-unsafe cardiac devices are only scanned off-label in 27% of university hospitals, and in an even smaller share of other institutions. Approximately 12% of the respondents reported MR-related accidents resulting in patient or personnel injury. Overall, there is the sentiment that MR safety education and regulation are needed., Conclusions: The European landscape in terms of MR safety is very heterogeneous, with different regulations across countries, and different procedures for MR safety training and their application in clinical routine. The European Society of Radiology is optimally positioned to play an active role in the harmonization of MR safety education and practices across Europe, and we are proposing a four-tiered framework for the development of a teaching curriculum for MR safety training., Critical Relevance Statement: There is room for raising awareness of MR safety issues to ensure patient safety, reduce accidents, and benefit more patients. We advocate for radiologist-led standardization and improvement of MR safety training as a way to address this problem., Key Points: Our survey of MR safety practices across Europe revealed significant heterogeneity in regulations, training, and scanning practices. There is a widespread lack of awareness and implementation of MR safety guidelines and diffuse uncertainty, under-scanning of eligible patients, and preventable accidents. The ESR proposes a harmonized, four-tiered MR safety training curriculum to standardize, and improve safety practices across Europe., (© 2024. The Author(s).)

Purpose: In this study, the effects of RF coupling on the magnitude and spatial patterns of RF‐induced heating near multiple wire‐like conducting implants (such as simultaneous electrical stimulation of stereoelectroencephalography electrodes) during MRI were assessed. Methods: Simulations and experimental measurements of RF‐induced temperature increases near partially immersed wire‐like conductors were performed using a phantom with a transmit/receive head coil on a 3T MRI system. The conductors consisted of either a pair of wires or a single simultaneous electrical stimulation of stereoelectroencephalography electrode with multiple contacts, and the locations and lengths of the conductors were varied to study the effect of electromagnetic coupling on RF‐induced heating. Results: The temperature increase near a wire within the phantom was dependent not only on its own location and length, but also on the locations and lengths of the other partially immersed wires. In the configurations that were studied, the presence of a second implant could increase the heating near the tip of the conductor by as much as 95%. Conclusion: The level of RF‐induced heating during an MR scan is affected significantly by RF coupling when more than one wire‐like implant is present. In some of the configurations studied, the heating was increased by the presence of a second conductor partially immersed in the phantom. Thus, RF coupling is an important factor to consider in the assessment of safety issues for MRI when multiple implants are present. [ABSTRACT FROM AUTHOR]

Magnetic resonance imaging (MRI) gradient coils produce acoustic noise due to coil conductor vibrations caused by large Lorentz forces. Accurate sound pressure levels and modeling of heating are essential for the assessment of gradient coil safety. This work reviews the state-of-the-art numerical methods used in accurate gradient coil modeling and prediction of sound pressure levels (SPLs) and temperature rise. We review several approaches proposed for noise level reduction of high-performance gradient coils, with a maximum noise reduction of 20 decibels (dB) demonstrated. An efficient gradient cooling technique is also presented.

Abstract Background Temporary epicardial pacing wires, implemented in patients during heart transplantation, are routinely removed before discharge. However, in some cases, these wires may remain in situ and are often considered as a contraindication for cardiovascular magnetic resonance (CMR) imaging in the future. Therefore, we aimed to provide data about safety and image quality of CMR in these patients. Methods This is a report on a subpopulation out of 88 patients after heart transplantation that were included in a prospective cohort study and underwent multiple CMR in their post-transplant course. During CMR, patients were monitored by electrocardiogram and all examinations were observed by a physician to document potential adverse events. Additionally, image quality was assessed by an imaging specialist. Results Nineteen of 88 patients included had temporary pacing wires in situ. These patients underwent a total of 51 CMR studies. No major adverse event and only one single, mild sensory event could be documented. All CMR studies showed preserved diagnostic image quality. Temporary pacing wires were visible in 100% of HASTE and cine sequences. In less than 50% of the examinations, temporary pacing wires were also visible in T1 and T2 mapping, short tau inversion recovery (STIR), and late gadolinium enhancement (LGE) sequences, without any impairment of image quality. Conclusions With a low event rate of only one mild adverse event during 51 CMR examinations (2%), CMR appears to be safe in patients with retained temporary epicardial pacing wires after heart transplantation. Moreover, image quality was not impaired by the presence of pacing wires.

BackgroundConventional guidewires are not suitable for use during cardiovascular magnetic resonance (CMR) catheterization. They employ metallic shafts for mechanical performance, but which are conductors subject to radiofrequency (RF) induced heating. To date, non-metallic CMR guidewire designs have provided inadequate mechanical support, trackability, and torquability. We propose a metallic guidewire for CMR that is by design intrinsically safe and that retains mechanical performance of commercial guidewires.MethodsThe NHLBI passive guidewire is a 0.035" CMR-safe, segmented-core nitinol device constructed using short nitinol rod segments. The electrical length of each segment is less than one-quarter wavelength at 1.5 Tesla, which eliminates standing wave formation, and which therefore eliminates RF heating along the shaft. Each of the electrically insulated segments is connected with nitinol tubes for stiffness matching to assure uniform flexion. Iron oxide markers on the distal shaft impart conspicuity. Mechanical integrity was tested according to International Organization for Standardization (ISO) standards. CMR RF heating safety was tested in vitro in a phantom according to American Society for Testing and Materials (ASTM) F-2182 standard, and in vivo in seven swine. Results were compared with a high-performance commercial nitinol guidewire.ResultsThe NHLBI passive guidewire exhibited similar mechanical behavior to the commercial comparator. RF heating was reduced from 13 °C in the commercial guidewire to 1.2 °C in the NHLBI passive guidewire in vitro, using a flip angle of 75°. The maximum temperature increase was 1.1 ± 0.3 °C in vivo, using a flip angle of 45°. The guidewire was conspicuous during left heart catheterization in swine.ConclusionsWe describe a simple and intrinsically safe design of a metallic guidewire for CMR cardiovascular catheterization. The guidewire exhibits negligible heating at high flip angles in conformance with regulatory guidelines, yet mechanically resembles a high-performance commercial guidewire. Iron oxide markers along the length of the guidewire impart passive visibility during real-time CMR. Clinical translation is imminent.

Purpose: Rapid detection and mitigation of radiofrequency (RF)‐induced implant heating during MRI based on small and low‐cost embedded sensors. Theory and Methods: A diode and a thermistor are embedded at the tip of an elongated mock implant. RF‐induced voltages or temperature change measured by these root mean square (RMS) sensors are used to construct the sensor Q‐Matrix (QS). Hazard prediction, monitoring and parallel transmit (pTx)‐based mitigation using these sensors is demonstrated in benchtop measurements at 300 MHz and within a 3T MRI. Results: QS acquisition and mitigation can be performed in <20 ms demonstrating real‐time capability. The acquisitions can be performed using safe low powers (<3 W) due to the high reading precision of the diode (126 µV) and thermistor (26 µK). The orthogonal projection method used for pTx mitigation was able to reduce the induced signals and temperatures in all 155 investigated locations. Using the QS approach in a pTx capable 3T MRI with either a two‐channel body coil or an eight‐channel head coil, RF‐induced heating was successfully assessed, monitored and mitigated while the image quality outside the implant region was preserved. Conclusion: Small (<1.5 mm3) and low‐cost (<1 €) RMS sensors embedded in an implant can provide all relevant information to predict, monitor and mitigate RF‐induced heating in implants, while preserving image quality. The proposed pTx‐based QS approach is independent of simulations or in vitro testing and therefore complements these existing safety assessments. [ABSTRACT FROM AUTHOR]

Background: Temporary epicardial pacing wires, implemented in patients during heart transplantation, are routinely removed before discharge. However, in some cases, these wires may remain in situ and are often considered as a contraindication for cardiovascular magnetic resonance (CMR) imaging in the future. Therefore, we aimed to provide data about safety and image quality of CMR in these patients. Methods: This is a report on a subpopulation out of 88 patients after heart transplantation that were included in a prospective cohort study and underwent multiple CMR in their post-transplant course. During CMR, patients were monitored by electrocardiogram and all examinations were observed by a physician to document potential adverse events. Additionally, image quality was assessed by an imaging specialist. Results: Nineteen of 88 patients included had temporary pacing wires in situ. These patients underwent a total of 51 CMR studies. No major adverse event and only one single, mild sensory event could be documented. All CMR studies showed preserved diagnostic image quality. Temporary pacing wires were visible in 100% of HASTE and cine sequences. In less than 50% of the examinations, temporary pacing wires were also visible in T1 and T2 mapping, short tau inversion recovery (STIR), and late gadolinium enhancement (LGE) sequences, without any impairment of image quality. Conclusions: With a low event rate of only one mild adverse event during 51 CMR examinations (2%), CMR appears to be safe in patients with retained temporary epicardial pacing wires after heart transplantation. Moreover, image quality was not impaired by the presence of pacing wires. [ABSTRACT FROM AUTHOR]

Fully bioresorbable scaffolds have been designed to overcome the limitations of traditional drug-eluting stents (DESs), which permanently cage the native vessel wall and pose possible complications. The ultrathin-strut designed sirolimus-eluting iron bioresorbable coronary scaffold system (IBS) shows comparable mechanical properties to traditional DESs and exhibits an adaptive degradation profile during target vessel healing, which makes it a promising candidate in all-comers patient population. For implanted medical devices, magnetic resonance (MR) imaging properties, including MR safety and compatibility, should be evaluated before its clinical use, especially for devices with intrinsic ferromagnetism. In this study, MR safety and compatibility of the IBS scaffold were evaluated based on a series of well-designed in-vitro, ex-vivo and in-vivo experiments, considering possible risks, including scaffold movement, over-heating, image artifact, and possible vessel injury, under typical MR condition. Traditional ASTM standards for MR safety and compatibility evaluation of intravascular devices were referred, but not only limited to that. The unique time-relevant MR properties of bioresorbable scaffolds were also discussed. Possible forces imposed on the scaffold during MR scanning and MR image artifacts gradually decreased along with scaffold degradation/absorption. Rigorous experiments designed based on a scientifically based rationale revealed that the IBS scaffold is MR conditional, though not MR compatible before complete absorption. The methodology used in the present study can give insight into the MR evaluation of magnetic scaffolds (bioresorbable) or stents (permanent).

Cardiovascular magnetic resonance (CMR) is a proven imaging modality for informing diagnosis and prognosis, guiding therapeutic decisions, and risk stratifying surgical intervention. Patients with a cardiac implantable electronic device (CIED) would be expected to derive particular benefit from CMR given high prevalence of cardiomyopathy and arrhythmia. While several guidelines have been published over the last 16 years, it is important to recognize that both the CIED and CMR technologies, as well as our knowledge in MR safety, have evolved rapidly during that period. Given increasing utilization of CIED over the past decades, there is an unmet need to establish a consensus statement that integrates latest evidence concerning MR safety and CIED and CMR technologies. While experienced centers currently perform CMR in CIED patients, broad availability of CMR in this population is lacking, partially due to limited availability of resources for programming devices and appropriate monitoring, but also related to knowledge gaps regarding the risk-benefit ratio of CMR in this growing population. To address the knowledge gaps, this SCMR Expert Consensus Statement integrates consensus guidelines, primary data, and opinions from experts across disparate fields towards the shared goal of informing evidenced-based decision-making regarding the risk-benefit ratio of CMR for patients with CIEDs., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Purpose: The risks of RF‐induced heating of active implantable medical device (AIMD) leads during MR examinations must be well understood and realistically assessed. In this study, we evaluate the potential additional risks of broken and abandoned (cut) leads. Methods: First, we defined a generic AIMD with a metallic implantable pulse generator (IPG) and a 100‐cm long lead containing 1 or 2 wires. Next, we numerically estimated the deposited in vitro lead‐tip power for an intact lead, as well as with wire breaks placed at 10 cm intervals. We studied the effect of the break size (wire gap width), as well as the presence of an intact wire parallel to the broken wire, and experimentally validated the numeric results for the configurations with maximum deposited in vitro lead‐tip power. Finally, we performed a Tier 3 assessment of the deposited in vivo lead‐tip power for the intact and broken lead in 4 high resolution virtual population anatomic models for over 54,000 MR examination scenarios. Results: The enhancement of the deposited lead‐tip power for the broken leads, compared to the intact lead, reached 30‐fold in isoelectric exposure, and 16‐fold in realistic clinical exposures. The presence of a nearby intact wire, or even a nearby broken wire, reduced this enhancement factor to <7‐fold over the intact lead. Conclusion: Broken and abandoned leads can pose increased risk of RF‐induced lead‐tip heating to patients undergoing MR examinations. The potential enhancement of deposited in vivo lead‐tip power depends on location and type of the wire break, lead design, and clinical routing of the lead, and should be carefully considered when performing risk assessment for MR examinations and MR conditional labeling. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the safety and image quality of extremity MR examinations performed with two MR conditional external fixators located in the MR bore. Materials and methods: Single-center retrospective study of a prospectively maintained imaging dataset that evaluated MR examinations of extremities in patients managed with external fixations instrumentation and imaged on a single 1.5T MR scanner. The fixation device was one of two MR-conditional instrumentation systems: DuPuy Synthes (aluminum, stainless steel, carbonium and Kevlar) or Dolphix temporary fixation system (PEEK-CA30). Safety events were recorded by the performing MR radiologic technologist. A study musculoskeletal radiologist assessed all sequences to evaluate for image quality, signal- and contrast-to-noise ratios (SNR/CNR), and injury patterns/findings. Results: In the 13 men and 9 women with a mean age of 42 years (range 18 to 72 years), most patients (19/22 patients; 86%) were involved with trauma resulting in extremity injury requiring external fixation. MR examinations included 19 knee, 2 ankle, and 1 elbow examinations. There were no adverse safety events, heating that caused patient discomfort, fixation dislodgement/perturbment, or early termination of MR examinations. All examinations were of diagnostic quality. Fat-suppressed proton density sequences had significantly higher SNR and CNR compared to STIR (p = 0.01 to 0.04). The lower SNR of STIR and increased quality of fat-suppressed proton density during the study period led to the STIR sequence being dropped in standard MR protocol. Conclusion: MR of the extremity using the two study MR conditional external fixators within the MR bore is safe and feasible. [ABSTRACT FROM AUTHOR]

During an MRI scan, the radiofrequency field from the scanner's transmit coil, but also the switched gradient fields, induce currents in any conductive object in the bore. This makes any metallic medical implant an additional risk for an MRI patient, because those currents can heat up the surrounding tissues to dangerous levels. This is one of the reasons why implants are, until today, considered a contraindication for MRI; for example, by scanner manufacturers. Due to the increasing prevalence of medical implants in our aging societies, such general exclusion is no longer acceptable. Also, it should be no longer needed, because of a much-improved safety-assessment methodology, in particular in the field of numerical simulations. The present article reviews existing literature on implant-related heating effects in MRI. Concepts for risk assessment and quantification are presented and also some first attempts towards an active safety management and risk mitigation. LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY: Stage 5. [ABSTRACT FROM AUTHOR]

• The E-field probe induced no visible alteration of the fields up to 11.7 T. • The E-field allowed accurate SAR measurement independently of complex heat exchanges. • The Uncertainty of measurement was below 3 % for a minimal SAR of 4.10-4 W/kg. • The SAR was 5.2 times higher at the center of the coil at 11.7 T than at 7 T. • The repeatability estimated with the coefficient of variation was 2.3%. SAR assessment is a major concern in MRI. The energy absorbed by tissues increases quadratically with the static magnetic field; therefore, ultra-high field (≥7 T) systems require careful dosimetry to exploit their potential. The objectives are to validate the use of electric-field probe for SAR assessment for high-field MRI, and to study the advantages and drawbacks of E-field measurements. The experiments were performed at 7 and 11.7 T on preclinical systems in a phantom with calibrated dielectric properties. Absolute values of the E-field were measured according to position inside a birdcage coil and electrical conductivity, local temperature increase were simultaneously evaluated with operating RF frequency, as well as the re-positioning precision through five repetitive measurements. Results yielded a 14.8 ± 0.36 W/kg SAR near the coil's capacitors compared to 6.8 ± 0.17 W/kg estimated at the center of the coil. The temperature rise was nevertheless higher in the center likely due to heat transfer effects. The SAR measured in similar conditions was 5.2 times higher at 11.7 T than at 7 T. The probes induced no visible artefact, and the test to estimate the reproducibility of positioning the sensors granted a low 2.3 % coefficient of variation. Measuring both the cause (E-field) and the effect (temperature rise) yielded different information, both useful in the context of EM simulation validation. [ABSTRACT FROM AUTHOR]

• Displacement measurements were peformed on several passive devices at 50 mT. • Image artifacts were very small for non-ferromagnic passive implants at 50 mT. • SAR simulations show that very long train length TSE sequences can be run safely. To investigate the displacement forces and image artifacts associated with passive medical implants for recently-developed low-field (<100 mT) MRI systems, and to compare these with values from higher field strengths used for clinical diagnosis. Setups were constructed to measure displacement forces in a permanent magnet-based Halbach array used for in vivo MRI at 50 mT, and results compared with measurements at 7 T. Image artifacts were assessed using turbo (fast) spin echo imaging sequences for four different passive medical implants: a septal occluder, iliac stent, pedicle screw and (ferromagnetic) endoscopic clip. Comparisons were made with artifacts produced at 1.5, 3 and 7 T. Finally, specific absorption rate (SAR) simulations were performed to determine under what operating conditions the limits might be approached at low-field. Displacement forces at 50 mT on all but the ferromagnetic implant were between 1 and 10 mN. Image artifacts at 50 mT were much less than at clinical field strengths for all passive devices, and with the exception of the ferromagnetic clip. SAR simulations show that very long echo train (>128) turbo spin echo sequences can be run with short inter-pulse times (5–10 ms) within SAR limits. This work presents the first evaluation of the effects of passive implants at field strengths less than 100 mT in terms of displacement forces, image artifacts and SAR. The results support previous claims that such systems can be used safely and usefully in challenging enviroments such as the intensive care unit. [ABSTRACT FROM AUTHOR]

Objective: To assess the effect of the electro-magnetic coupling of endovascular stents on their RF heating potential in MRI. Methods: A custom-built electro-optic E-field probe is used to perform measurements of the scattered E-field at a distance of 2 mm to stent samples with submillimeter resolution. Various combinations of stent lengths are measured at 124 MHz (3T MRI Larmor frequency) with varying gap and overlap between the stents, with and without stent coating, and with distilled water and saline solution as surrounding media. The results are compared to theoretically derived E-field distributions. Results: At an overlap of 10 mm the E-field pattern of two stents collapses to a single dipole indicating excellent coupling between the stents. E-field intensities substantially increase/decrease up to 5-fold/2.5-fold if the total length of the two combined stents is closer/further away from the resonance length of the single stents. Stent coating and conductivity of the surrounding medium strongly influence the E-field patterns of overlapping stents. Measured and calculated E-field patterns are in good agreement. Conclusion: Electro-optic E-field measurements are a valuable tool for RF safety assessments in both single as well as coupled stents. Significance: RF induced heating of single stents during MRI has been extensively studied. However, in clinical practice often two or more stents are implanted in close proximity which can substantially change the pattern of the scattered electric fields and the localization and intensity of hot spots. In this study a detailed assessment of the coupling of stents during RF excitation is given. [ABSTRACT FROM AUTHOR]

Introduction: While wideband segmented, breath‐hold late gadolinium‐enhancement (LGE) cardiovascular magnetic resonance (CMR) has been shown to suppress image artifacts associated with cardiac‐implanted electronic devices (CIEDs), it may produce image artifacts in patients with arrhythmia and/or dyspnea. Single‐shot LGE is capable of suppressing said artifacts. We sought to compare the performance of wideband single‐shot free‐breathing LGE against the standard and wideband‐segmented LGEs in CIED patients. Methods and Results: We retrospectively identified all 54 consecutive patients (mean age: 61 ± 15 years; 31% females) with CIED who had undergone CMR with standard segmented, wideband segmented, and/or wideband single‐shot LGE sequences as part of quality assurance for determining best clinical practice at 1.5 T. Two raters independently graded the conspicuity of myocardial scar or normal myocardium and the presence of device artifact level on a 5‐point Likert scale (1: worst; 3: acceptable; 5: best). Summed visual score (SVS) was calculated as the sum of conspicuity and artifact scores (SVS ≥ 6 defined as diagnostically interpretable). Median conspicuity and artifact scores were significantly better for wideband single‐shot LGE (F = 24.2, p <.001) and wideband‐segmented LGE (F = 20.6, p <.001) compared to standard‐segmented LGE. Among evaluated myocardial segments, 72% were deemed diagnostically interpretable—defined as SVS ≥ 6—for standard‐segmented LGE, 89% were deemed diagnostically interpretable for wideband‐segmented LGE, and 94% segments were deemed diagnostically interpretable for wideband single‐shot LGE. Conclusions: Wideband single‐shot LGE and wideband‐segmented LGE produced similarly improved image quality compared to standard LGE. [ABSTRACT FROM AUTHOR]

Over the past decade, there has been a dramatic increase in the number of patients undergoing prostate MRI scans. Patients presenting for prostate MRI are an ageing population and may present with a variety of passive or active implants and devices. These implants and devices can be MR safe or MR conditional or MR unsafe. Patients with certain MR-conditional active implants and devices can safely obtain prostate MRI in a specified MR environment within specific MR imaging parameters. Prostate MRI and PET-MRI in patients with passive implants such as hip prostheses, fiducial markers for SBRT, brachytherapy seeds and prostatectomy bed clips have unique concerns for image optimization that can cause geometric distortion of the diffusion-weighted imaging (DWI) sequence. We discuss strategies to overcome these susceptibility artifacts. Prostate MRI in patients with MR conditional active implants such as cardiac implantable electronic devices (CIED) also require modification of imaging parameters and magnet strength. In this setting, a diagnostic quality prostate MRI can be performed at a lower magnet strength (1.5 T) along with modification of imaging parameters to ensure patient safety. Imaging strategies to minimize susceptibility artifact and decrease the specific absorption rate (SAR) in both settings are described. Knowledge of MR safety considerations and imaging strategies specific to prostate MRI and PET-MRI in patients with implants and devices is essential to ensure diagnostic-quality MR images and patient safety. [ABSTRACT FROM AUTHOR]

Purpose: To implement a modular, flexible, open‐source hardware configuration for parallel transmission (pTx) experiments on medical implant safety and to demonstrate real‐time mitigation strategies for radio frequency (RF) induced implant heating based on sensor measurements. Methods: The hardware comprises a home‐built 8‐channel pTx system (scalable to 32‐channels), wideband power amplifiers and a positioning system with submillimeter precision. The orthogonal projection (OP) method is used to mitigate RF induced tip heating and to maintain sufficient B1+ for imaging. Experiments are performed at 297MHz and inside a clinical 3T MRI using 8‐channel pTx RF coils, a guidewire substitute inside a phantom with attached thermistor and time‐domain E‐field probes. Results: Repeatability and precision are ~3% for E‐field measurements including guidewire repositioning, ~3% for temperature slopes and an ~6% root‐mean‐square deviation between B1+ measurements and simulations. Real‐time pTx mitigation with the OP mode reduces the E‐fields everywhere within the investigated area with a maximum reduction factor of 26 compared to the circularly polarized mode. Tip heating was measured with ~100 μK resolution and ~14 Hz sampling frequency and showed substantial reduction for the OP vs CP mode. Conclusion: The pTx medical implant safety testbed presents a much‐needed flexible and modular hardware configuration for the in‐vitro assessment of implant safety, covering all field strengths from 0.5‐7 T. Sensor based real‐time mitigation strategies utilizing pTx and the OP method allow to substantially reduce RF induced implant heating while maintaining sufficient image quality without the need for a priori knowledge based on simulations or in‐vitro testing. [ABSTRACT FROM AUTHOR]

In the context of the increasing spread of cardiac active implantable heart devices (CIEDs) in the population and of the wide diagnostic/therapeutic utility of magnetic resonance (MRI) examinations, the goal of this paper is to provide the experience of the Santa Maria Nuova Hospital of the USL Tuscany Center in Florence and to report an organizational proposal to perform, in the hospital settings, MRI examinations on patients carrying CIED. This report is intended to show the operational choices of a Radiology Department which organizes this activity in accordance with the new Italian regulatory framework in the field of safety of MR sites (Ministero della Salute in Decreto Ministeriale 10 agosto 2018 Determinazione degli standard di sicurezza e impiego per le apparecchiature a risonanza magnetica, 2018). [ABSTRACT FROM AUTHOR]

Purpose: Deep brain stimulation electrodes composed of carbon fibers were tested as a means of administering and imaging magnetic resonance electrical impedance tomography (MREIT) currents. Artifacts and heating properties of custom carbon‐fiber deep brain stimulation (DBS) electrodes were compared with those produced with standard DBS electrodes. Methods: Electrodes were constructed from multiple strands of 7‐μm carbon‐fiber stock. The insulated carbon electrodes were matched to DBS electrode diameter and contact areas. Images of DBS and carbon electrodes were collected with and without current flow and were compared in terms of artifact and thermal effects in phantoms or tissue samples in 7T imaging conditions. Effects on magnetic flux density and current density distributions were also assessed. Results: Carbon electrodes produced magnitude artifacts with smaller FWHM values compared to the magnitude artifacts around DBS electrodes in spin echo and gradient echo imaging protocols. DBS electrodes appeared 269% larger than actual size in gradient echo images, in sharp contrast to the negligible artifact observed in diameter‐matched carbon electrodes. As expected, larger temperature changes were observed near DBS electrodes during extended RF excitations compared with carbon electrodes in the same phantom. Magnitudes and distribution of magnetic flux density and current density reconstructions were comparable for carbon and DBS electrodes. Conclusion: Carbon electrodes may offer a safer, MR‐compatible method for administering neuromodulation currents. Use of carbon‐fiber electrodes should allow imaging of structures close to electrodes, potentially allowing better targeting, electrode position revision, and the facilitation of functional imaging near electrodes during neuromodulation. [ABSTRACT FROM AUTHOR]

Purpose: To dynamically minimize radiofrequency (RF)‐induced heating of an active catheter through an automatic change of the termination impedance. Methods: A prototype wireless module was designed that modifies the input impedance of an active catheter to keep the temperature rise during MRI below a threshold, ΔTmax. The wireless module (MR safety watchdog; MRsWD) measures the local temperature at the catheter tip using either a built‐in thermistor or external data from a fiber‐optical thermometer. It automatically changes the catheter input impedance until the temperature rise during MRI is minimized. If ΔTmax is exceeded, RF transmission is blocked by a feedback system. Results: The thermistor and fiber‐optical thermometer provided consistent temperature data in a phantom experiment. During MRI, the MRsWD was able to reduce the maximum temperature rise by 25% when operated in real‐time feedback mode. Conclusion: This study demonstrates the technical feasibility of an MRsWD as an alternative or complementary approach to reduce RF‐induced heating of active interventional devices. The automatic MRsWD can reduce heating using direct temperature measurements at the tip of the catheter. Given that temperature measurements are intrinsically slow, for a clinical implementation, a faster feedback parameter would be required such as the RF currents along the catheter or scattered electric fields at the tip. [ABSTRACT FROM AUTHOR]

MR-safety remains a concern among MR professionals. We aimed to evaluate the extent of MR-related incidents using a national database and a questionnaire among MR professionals and to identify possible predictors for MR-related incidents. MR-related incidents reported to a national database from 2015 to 2017 were scrutinized. A national online survey focussing on MR safety and education was performed. Quantitative analyses, descriptive statistics and regression analyses were used. The database included 196, 97 and 100 direct MR-related incidents in 2015, 2016 and 2017, respectively. Regarding the questionnaire, 208 MR professionals responded. Within the last year, 33% had been involved in an MR-related incident that was reported in the national database. At some time in their working life, 53% had been involved in an MR-related incident that was reported, but 25% had been involved in an incident that was not reported. The responses to the questionnaire reflected far more incidents than those reported to the database for all categories. Sixty-one percent of respondents indicated that external personnel in the MR environment are a safety risk. External personnel in the MR environment were found to be a predictor for reported and unreported MR-related incidents with odds ratio (OR) = 2.07; p = 0.033 and OR = 5.17; p = 0.0005 respectively. There seems to be severe underreporting of MR-related incidents. External personnel in the MR-environment and scanning patients in anaesthesia were found to be predictors for both reported and unreported MR-related incidents. Regulations regarding the minimum required MR safety education of different groups of MR professionals and external personnel are recommended. Enforcing MR safety education and highlighting the importance of MR safety within hospital organisations would contribute to better patient and personnel safety. [ABSTRACT FROM AUTHOR]

The need for a guidance document on MR safe practices arose from a growing awareness of the MR environment's potential risks and adverse event reports involving patients, equipment, and personnel. Initially published in 2002, the American College of Radiology White Paper on MR Safety established de facto industry standards for safe and responsible practices in clinical and research MR environments. The most recent version addresses new sources of risk of adverse events, increases awareness of dynamic MR environments, and recommends that those responsible for MR medical director safety undergo annual MR safety training. With regular updates to these guidelines, the latest MR safety concerns can be accounted for to ensure a safer MR environment where dangers are minimized. Level of Evidence: 1 Technical Efficacy Stage: 5 J. Magn. Reson. Imaging 2020;51:331-338. [ABSTRACT FROM AUTHOR]

Purpose: To establish peripheral nerve stimulation (PNS) thresholds for an ultra‐high performance magnetic field gradient subsystem (simultaneous 200‐mT/m gradient amplitude and 500‐T/m/s gradient slew rate; 1 MVA per axis [MAGNUS]) designed for neuroimaging with asymmetric transverse gradients and 42‐cm inner diameter, and to determine PNS threshold dependencies on gender, age, patient positioning within the gradient subsystem, and anatomical landmarks. Methods: The MAGNUS head gradient was installed in a whole‐body 3T scanner with a custom 16‐rung bird‐cage transmit/receive RF coil compatible with phased‐array receiver brain coils. Twenty adult subjects (10 male, mean ± SD age = 40.4 ± 11.1 years) underwent the imaging and PNS study. The tests were repeated by displacing subject positions by 2‐4 cm in the superior–inferior and anterior–posterior directions. Results: The x‐axis (left–right) yielded mostly facial stimulation, with mean ΔGmin = 111 ± 6 mT/m, chronaxie = 766 ± 76 µsec. The z‐axis (superior–inferior) yielded mostly chest/shoulder stimulation (123 ± 7 mT/m, 620 ± 62 µsec). Y‐axis (anterior–posterior) stimulation was negligible. X‐axis and z‐axis thresholds tended to increase with age, and there was negligible dependency with gender. Translation in the inferior and posterior directions tended to increase the x‐axis and z‐axis thresholds, respectively. Electric field simulations showed good agreement with the PNS results. Imaging at MAGNUS gradient performance with increased PNS threshold provided a 35% reduction in noise‐to‐diffusion contrast as compared with whole‐body performance (80 mT/m gradient amplitude, 200 T/m/sec gradient slew rate). Conclusion: The PNS threshold of MAGNUS is significantly higher than that for whole‐body gradients, which allows for diffusion gradients with short rise times (under 1 msec), important for interrogating brain microstructure length scales. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate radiofrequency (RF) induced tissue heating around aneurysm clips during a 7T head MR examination and to determine the decoupling distance between multiple implanted clips. Methods: A total of 120 RF exposure scenarios of clinical relevance were studied using specific absorption rate and temperature simulations. Variations between scenarios included 2 clips (18.8 and 51.5 mm length), 2 MR‐operating modes, 2 head models, and 3 thermoregulation models. Furthermore, a conservative approach was developed to allow for safe scans of patients with aneurysm clips even if detailed information on the implanted clip is unknown. A dedicated simulation‐based approach was applied to determine the decoupling distance between multiple implanted clips. Results: For all 60 clinical scenarios with the 18.8‐mm‐long clip, the absolute tissue temperature remained below regulatory limits. For 15 of 60 scenarios with the 51.5‐mm‐long clip, limits were slightly exceeded (less than 1°C). The conservative approach led to a maximum time‐averaged input power of the RF coil of 3.3W. The corresponding B1+ is 1.32 µT. A decoupling distance of 35 mm allows the aneurysm clips to be treated as uncoupled from one other. Conclusion: Safe scanning conditions with respect to RF‐induced heating can be applied for single or decoupled aneurysm clips in a 7T ultra‐high field MRI setting. Multiple aneurysm clips separated by less than 35 mm need further investigations. [ABSTRACT FROM AUTHOR]

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