Magnetic resonance safety

Evaluating Adherence to Safety Standards for Physical Space Design, Equipment, and Patient and Staff Protection in Magnetic Resonance Imaging Centers: A Descriptive Cross-sectional Study

ABSTRACT

Magnetic resonance imaging (MRI) has revolutionized disease diagnosis and treatment. However, the technology poses safety risks, such as exposure to magnetic fields, RF pulses, and cryogens, necessitating strict adherence to safety protocols to protect patients and healthcare workers. This cross-sectional descriptive study assessed compliance with MRI safety standards in Khuzestan province, Iran) imaging centers, focusing on electromagnetic fields and other key safety domains. A 61-item researcher-developed checklist, based on international safety guidelines, was used to evaluate safety protocols in 11 MRI centers across seven domains, including facility design, equipment labeling, static magnetic and gradient fields, RF waves, cryogens, patient and staff protection, and infection control. MRI staff responded with yes/no answers. Responses to three additional questions also were collected. Data analysis was conducted using SPSS 26. A p-value < 0.05 was considered statistically significant. Overall, facility design scores ranged from 54.5% to 100%, but static magnetic field safety ratings were significantly lower (25% to 100%). Although safety equipment availability reached 100% in some centers, gaps were noted in labeling ferromagnetic devices. Infection control adherence was high, but only seven centers featured seamless flooring in the magnet room. Cryogen safety showed partial compliance with some centers lacking exhaust fans. Employee and patient safety measures were inconsistent, with one center scoring as low as 18%. While MRI centers demonstrated strengths in infection control and facility design, critical deficiencies in static magnetic field safety and emergency protocols highlight the need for targeted training, regular audits, and updated policies. Addressing these gaps is essential to enhancing MRI safety practices and aligning with international standards.

Development and fundamental psychometric properties of the Magnetic Resonance Imaging Child-Anxiety Questionnaire (MRIC-AQ)

INTRODUCTION

Magnetic Resonance Imaging is known to provoke anxiety among children, and they may need to be examined with the help of anaesthesia, which has risks. An instrument is needed to evaluate children's anxiety related to a procedure with Magnetic Resonance Imaging. The study aims to adapt and evaluate a children's version of the Magnetic Resonance Imaging-Anxiety Questionnaire.

METHODS

The 'Magnetic Resonance Imaging Child-Anxiety Questionnaire' (MRIC-AQ) was drafted by an expert group consisting of a paediatric nurse, a teacher and two radiographers. This version was discussed in focus groups consisting of 10 children between the ages of four and 12 years. The children's suggestions were summarised and analysed using thematic analysis. The revised questionnaire was again discussed with focus groups of children before a paediatric nurse made final readjustments. For a basic psychometric analysis, children undergoing MRI-examinations without anaesthesia were asked to answer the MRIC-AQ.

RESULTS

Responses to the questionnaire were gathered from 77 children (girls = 44, boys = 33) aged five to12 years (M = 9.3, SD = 1.7). Only two missing data points were found. The median of the total scale score was 25 (P25-P75 = 21-29), which is below the midpoint of the scale. The Cronbach's alpha was 0.84 (95 % CI = 0.78-0.89).

CONCLUSION

The MRIC-AQ has been developed with the help of children. It has satisfactory elementary psychometric properties and will be a useful tool for investigating different interventions for children.

IMPLICATIONS FOR PRACTICE

This new instrument (MRIC-AQ) is considered to be of great value when different kinds of interventions are evaluated, all to make MRI examinations as positive an experience as possible. This helps children to undergo examinations without fear.

[Health risks for medical personnel due to magnetic fields in magnetic resonance imaging]

The current state of medical and scientific knowledge on the effects of exposure to electromagnetic fields on workers in the field of clinical magnetic resonance imaging (MRI) is summarized here.A systematic literature search was conducted to analyze the health risks to medical personnel from magnetic fields in MRI. A total of 7273 sources were identified, with 7139 being excluded after screening of the title and abstract. After full-text screening, 34 sources remained and were included in this paper.There are a number of scientific publications on the occurrence of short-term sensory effects such as vertigo, metallic taste, phosphenes as well as on the occurrence of neurocognitive and neurobehavioral effects. For example, short-term exposure to clinical magnetic fields has been reported to result in a 4% reduction in speed and precision and a 16% reduction in visual contrast sensitivity at close range. Both eye-hand precision and coordination speed are affected. The long-term studies concern, among other things, the influence of magnetic fields on sleep quality, which could be linked to an increased risk of accidents. The data on the exposure of healthcare workers to magnetic fields during pregnancy is consistently outdated. However, it has been concluded that there are no particular deviations with regard to the duration of pregnancy, premature births, miscarriages, and birth weight. Epidemiological studies are lacking. With a focus on healthcare personnel, there is a considerable need for high-quality data, particularly on the consequences of long-term exposure to electromagnetic fields from clinical MRI and the effects on pregnancy. · Short-term sensory effects such as vertigo, metallic taste, phosphenes as well as neurocognitive and neurological behavioral effects may occur upon exposure to magnetic fields.. · Long-term effects mainly concern quality of sleep, which can be associated with an increased risk of accidents.. · When pregnant women were exposed to magnetic fields, no particular deviations were found with regard to the duration of pregnancy, premature births, miscarriages, and birth weight.. · König AM, Pöschke A, Mahnken AH. Health risks for medical personnel due to magnetic fields in magnetic resonance imaging. Rofo 2025; 197: 135-144.

The Evolution of Ventriculoperitoneal Shunt Valves and Why They Fail

This article reviews the historical progression of ventriculoperitoneal shunt valve designs with the goal of providing an understanding of their functionality and failure mechanisms. While shunting is the predominant treatment for hydrocephalus, the statistics of overall shunt failure remain high, and valve failure is responsible for a significant percentage of revision surgeries. Therefore, this review spans valve evolution from an engineering perspective with an emphasis on discussing potential failure mechanisms and patient-specific valve selection. Information is provided on the importance of valves in hydrocephalus treatment with discussion on each class of valves and their advantages and shortcomings. Substantial development over decades has significantly improved valve functionality, and ongoing research continues to provide more robust valves and shunt systems for hydrocephalus management.

Updates on the MR safety guidelines - Essentials for radiologists

Magnetic Resonance Imaging (MRI) is a sophisticated diagnostic tool that utilizes the magnetic properties of biological tissue to generate detailed images of internal structures without the use of ionizing radiation. Despite its benefits in providing high-contrast images of soft tissues, the strong magnetic fields used in MRI present a unique safety challenge. Increasing MRI-related accidents and the prevalence of patients with metallic implants in recent years underscore the critical need for stringent MR safety protocols. This article reviews the latest 2024 updates in the MRI safety manual by the American College of Radiology (ACR), highlighting the comprehensive efforts to manage risks associated with MRI, including projectile and burn incidents, patients with medical devices, and emerging complex MRI environments. The manual emphasizes the importance of specialized training for healthcare professionals to navigate the complexities of MRI safety to ensure patient and staff safety. This review also touches on the dynamic landscape of MRI safety standards, driven by technological advances and evolving clinical practices, aiming to provide a thorough understanding of current best practices in MRI safety management. LIST OF UPDATES.

Innovative applications of advanced nanomaterials in cerebrovascular imaging

Cerebrovascular imaging is essential for the diagnosis, treatment, and prognosis of cerebrovascular disease, including stroke, aneurysms, and vascular malformations. Conventional imaging techniques such as MRI, CT, DSA and ultrasound have their own strengths and limitations, particularly in terms of resolution, contrast and safety. Recent advances in nanotechnology offer new opportunities for improved cerebrovascular imaging. Nanomaterials, including metallic nanoparticles, magnetic nanoparticles, quantum dots, carbon-based nanomaterials, and polymer nanoparticles, show great potential due to their unique physical, chemical, and biological properties. This review summarizes recent advances in advanced nanomaterials for cerebrovascular imaging and their applications in various imaging techniques, and discusses challenges and future research directions. The aim is to provide valuable insights for researchers to facilitate the development and clinical application of these innovative nanomaterials in cerebrovascular imaging.

Patient flow analysis with fast-track MRI for suspected stroke in the emergency department and associated non-comprehensive stroke center

Background

Good outcomes in stroke care require swift diagnostics, for which magnetic resonance imaging (MRI) as first-line brain imaging is superior to computed tomography scans. Reduced length of stay (LOS) in hospital and emergency departments (ED) may optimize resource use. Fast-track stroke MRI was implemented as the primary imaging technique for suspected stroke, in the ED at Copenhagen University Hospital-Herlev and Gentofte in 2020.

Objectives

We aimed to describe and compare LOS, MRI utilization, and the rate of strokes versus stroke-mimicking conditions on the stroke ward, before and after the implementation of fast-track MRI.

Design and method

In this cross-sectional study, we used data from admissions to the neurologic ED and associated non-comprehensive stroke unit. We compared two time periods, that is, January 1-December 31, 2019, and January 1-December 31, 2020, before and after the implementation of fast-track stroke MRI.

Results

There were 6650 admissions before and 7201 after implementation of fast-track stroke MRI. After implementation, we observed reductions in average LOS in hospitals from 56.0 to 38.6 h (p < 0.001), and LOS in ED from 9.17 to 8.63 h (p < 0.001). The use of inpatient MRI increased significantly, and the rate of acute ischemic stroke patients on the ward increased yet the rate of non-strokes remained unchanged. The association between shorter admissions and access to MRI remained (odds ratio 1.81, p < 0.001), after adjusting for sex, age, weekend admissions, and lockdown periods.

Conclusion

Fast-track stroke MRI in ED associated with reduced LOS in hospital.

Novel nonmagnetic abutment designs for facial prostheses: an experimental study

Background/aim

This in vitro study was undertaken with the aim of evaluating and comparing the retentive forces of novel nonmagnetic abutment designs developed as alternatives to conventional magnetic abutments for facial prostheses.

Materials and methods

A plexiglass model was constructed and two extraoral implants were placed in these blocks in a parallel position. Nonmagnetic abutments made of titanium were fabricated and screwed onto the implants. The nonmagnetic systems represent a novel design and include two different abutment designs (type 1 and type 2) with silicone attachments. Retentive force values for the three abutment types of a conventional magnetic system (CMS), the nonmagnetic abutment type 1 system (NMS1), and the nonmagnetic abutment type 2 system (NMS2) were measured at the 0th, 120th, 360th, 720th, and 1440th dislodging cycles using a test machine. Given the data's distribution characteristics, nonparametric tests were used for analysis. The Kruskal-Wallis test was used to evaluate significant differences among groups, followed by Dunn's posthoc test for specific group comparisons. The Friedman test compared the number of dislodging cycles for each group, and the Benjamini-Hochberg adjusted Wilcoxon sign-rank test was used for pairwise comparisons.

Results

Both NMS1 and NMS2 exhibited significantly higher retentive forces compared to CMS for the same dislodging cycles (p < 0.01). The NMS1 group showed the highest initial retentive force (9.98 ± 0.89 N), followed by the NMS2 group (9.65 ± 0.35 N), but this difference was not statistically significant. Significant differences in retention force values were observed among the three groups across the dislodging cycles (p < 0.001). The lowest retentive force in the last dislodging cycle was observed in the CMS group (3.39 ± 0.04 N). Additionally, the retention forces decreased in all groups with each increasing dislodging cycle.

Conclusion

The two newly developed nonmagnetic systems displayed higher retentive forces compared to the magnetic systems and can be considered viable alternative abutment options for facial prostheses.

Systematic review of MRI safety literature in relation to radiofrequency thermal injury prevention

INTRODUCTION

Magnetic resonance imaging (MRI) is a rapidly evolving modality, generally considered safe due to lack of ionising radiation. While MRI technology and techniques are improving, many of the safety concerns remain the same as when first established. Patient thermal injuries are the most frequently reported adverse event, accounting for 59% of MRI incidents to the Food and Drug Administration (FDA). Surveys indicate many incidents remain unreported. Patient thermal injuries are preventable and various methods for their mitigation have been published. However, recommendations can be variable, fragmented and confusing. The aim of this systematic review was to synthesise the evidence on MRI safety and associated skin injuries and offer comprehensive recommendations for radiographers to prevent skin thermal injuries.

METHODS

Four journal databases were searched for sources published January 2010-May 2023, presenting information on MRI safety and thermal injuries.

RESULTS

Of 26,801 articles returned, after careful screening and based on the eligibility criteria, only 79 articles and an additional 19 grey literature sources were included (n = 98). Included studies were examined using thematic analysis to determine if holistic recommendations can be provided to assist in preventing skin burns. This resulted in three simplified recommendations: Remove any electrically conductive items Insulate the patient to prevent any conductive loops or contact with objects Communicate regularly CONCLUSION: By implementing the above recommendations, it is estimated that 97% of skin burns could be prevented. With thermal injuries continuing to impact MRI safety, strategies to prevent skin burns and heating are essential. Assessing individual risks, rather than blanket policies, will help prevent skin thermal injuries occurring, improving patient care.

Six-Degree-of-Freedom Freehand 3D Ultrasound: A Low-Cost Computer Vision-Based Approach for Orthopedic Applications

In orthopedics, X-rays and computed tomography (CT) scans play pivotal roles in diagnosing and treating bone pathologies. Machine bulkiness and the emission of ionizing radiation remain the main problems associated with these techniques. The accessibility and low risks related to ultrasound handling make it a popular 2D imaging method. Indeed, 3D ultrasound assembles 2D slices into a 3D volume. This study aimed to implement a probe-tracking method for 6 DoF 3D ultrasound. The proposed method involves a dodecahedron with ArUco markers attached, enabling computer vision tracking of the ultrasound probe's position and orientation. The algorithm focuses on the data acquisition phase but covers the basic reconstruction required for data generation and analysis. In the best case, the analysis revealed an average error norm of 2.858 mm with a standard deviation norm of 5.534 mm compared to an infrared optical tracking system used as a reference. This study demonstrates the feasibility of performing volumetric imaging without ionizing radiation or bulky systems. This marker-based approach shows promise for enhancing orthopedic imaging, providing a more accessible imaging modality for helping clinicians to diagnose pathologies regarding complex joints, such as the shoulder, replacing standard infrared tracking systems known to suffer from marker occlusion problems.

Point-of-Care Bedside Brain Magnetic Resonance Imaging Is Safe in Extracorporeal Membrane Oxygenation Patients With Swan Ganz Catheters: A Phantom Experiment and Single Center Experience

INTRODUCTION

More than 1.2 million pulmonary artery catheters (PACs) are used in cardiac patients per annum within the United States. However, it is contraindicated in traditional 1.5 and 3T magnetic resonance imaging (MRI) scans. We aimed to test preclinical and clinical safety of using this imaging modality given the potential utility of needing it in the clinical setting.

METHODS

We conducted two phantom experiments to ensure that the electromagnetic field power deposition associated with bare and jacketed PACs was safe and within the acceptable limit established by the Food and Drug Administration. The primary end points were the safety and feasibility of performing Point-of-Care (POC) MRI without imaging-related adverse events. We performed a preclinical computational electromagnetic simulation and evaluated these findings in nine patients with PACs on veno-arterial extracorporeal membrane oxygenation.

RESULTS

The phantom experiments showed that the baseline point specific absorption rate through the head averaged 0.4 W/kg. In both the bare and jacketed catheters, the highest net specific absorption rates were at the neck entry point and tip but were negligible and unlikely to cause any heat-related tissue or catheter damage. In nine patients (median age 66, interquartile range 42-72 y) with veno-arterial extracorporeal membrane oxygenation due to cardiogenic shock and PACs placed for close hemodynamic monitoring, POC MRI was safe and feasible with good diagnostic imaging quality.

CONCLUSIONS

Adult ECMO patients with PACs can safely undergo point-of-care low-field (64 mT) brain MRI within a reasonable timeframe in an intensive care unit setting to assess for acute brain injury that might otherwise be missed with conventional head computed tomography.

Diagnostic Accuracy of Transvaginal Ultrasound and Magnetic Resonance Imaging for the Detection of Myometrial Infiltration in Endometrial Cancer: A Systematic Review and Meta-Analysis

In endometrial cancer (EC), deep myometrial invasion (DMI) is a prognostic factor that can be evaluated by various imaging methods; however, the best method of choice is uncertain. We aimed to compare the diagnostic performance of two-dimensional transvaginal ultrasound (TVS) and magnetic resonance imaging (MRI) in the preoperative detection of DMI in patients with EC. Pubmed, Embase and Cochrane Library were systematically searched in May 2023. We included original articles that compared TVS to MRI on the same cohort of patients, with final histopathological confirmation of DMI as reference standard. Several subgroup analyses were performed. Eighteen studies comprising 1548 patients were included. Pooled sensitivity and specificity were 76.6% (95% confidence interval (CI), 70.9-81.4%) and 87.4% (95% CI, 80.6-92%) for TVS. The corresponding values for MRI were 81.1% (95% CI, 74.9-85.9%) and 83.8% (95% CI, 79.2-87.5%). No significant difference was observed (sensitivity: p = 0.116, specificity: p = 0.707). A non-significant difference between TVS and MRI was observed when no-myometrium infiltration vs. myometrium infiltration was considered. However, when only low-grade EC patients were evaluated, the specificity of MRI was significantly better (p = 0.044). Both TVS and MRI demonstrated comparable sensitivity and specificity. Further studies are needed to assess the presence of myometrium infiltration in patients with fertility-sparing wishes.

Navigated and individual α-peak-frequency-guided transcranial magnetic stimulation in male patients with treatment-refractory schizophrenia

BACKGROUND

Previous electroencephalography (EEG) studies have indicated altered brain oscillatory α-band activity in schizophrenia, and treatment with repetitive transcranial magnetic stimulation (rTMS) using individualized α-frequency has shown therapeutic effects. Magnetic resonance imaging-based neuronavigation methods allow stimulation of a specific cortical region and improve targeting of rTMS; therefore, we sought to study the efficacy of navigated, individual α-peak-frequency-guided rTMS (αTMS) on treatment-refractory schizophrenia.

METHODS

We recruited medication-refractory male patients with schizophrenia or schizoaffective disorder in this doubleblind, sham-controlled study. We randomized patients to a 3-week course of either active αTMS or sham stimulation applied to the left dorsolateral prefrontal cortex (DLPFC). We assessed participants with the Positive and Negative Syndrome Scale (PANSS) and the Clinical Global Impression Scale (CGI) at baseline and after treatment. We conducted a follow-up assessment with the PANSS 3 months after intervention.

RESULTS

We included 44 patients. After treatment, we observed a significantly higher PANSS total score (p = 0.029), PANSS general psychopathology score (p = 0.027) and PANSS 5-factor model cognitive-disorganized factor score (p = 0.011) in the αTMS group than the sham group. In addition, the CGI-Improvement score was significantly higher among those who received αTMS compared with sham stimulation (p = 0.048).

LIMITATIONS

The limited number of study participants included only male patients. Depression was not formally evaluated.

CONCLUSION

Navigated αTMS to the left DLPFC reduced total, general psychopathological, and cognitive-disorganized symptoms of schizophrenia. These results provide evidence for the therapeutic efficacy of individual α-peak-frequency-guided rTMS in treatment-refractory schizophrenia.

CLINICAL TRIAL REGISTRATION

NCT01941251; ClinicalTrials.gov.

MRI Data Analysis in Malformations of Cortical Development

Brain magnetic resonance imaging (MRI) is a noninvasive imaging modality that utilizes powerful magnets and radio waves to generate detailed images of the brain, making it a valuable tool for investigating malformations of cortical development (MCD). Various MRI techniques, including 3D T1-weighted, multiplanar thin-sliced T2-weighted, and 3D fluid-attenuated inversion recovery (FLAIR) sequences, can provide high-resolution images with excellent spatial and contrast resolution, allowing for a detailed visualization of cortical anatomy and abnormalities. Almost all MCD can be detected and characterized using MRI. Advanced techniques, such as arterial spin labeling MR perfusion, diffusion tensor imaging (DTI), and functional MRI (fMRI), may be used to improve the detection rate of these malformations and to plan surgery in case of drug-resistant epilepsy. However, there are also limitations related to high cost, relatively low availability, need for sedation or anesthesia, and limited sensitivity for detecting subtle focal cortical malformations. Despite these limitations, brain MRI plays a crucial role in the investigation of MCD, providing valuable information for diagnosis, treatment planning, and patient management.

Imaging modalities for non-acute pathologies of the foot and ankle

Chronic foot and ankle pain, in contrast to acute traumatic injuries, presents a diagnostic challenge due to its diverse underlying causes. Accurate diagnosis often necessitates the utilization of various imaging modalities, emphasizing the importance of selecting the most appropriate one. The intricate structure of the foot, composed of multiple bones and supported by soft tissues like ligaments and plantar fascia, gives rise to a spectrum of mechanical disorders, including stress fractures, plantar fasciitis, Morton's neuroma, and more. In addition to mechanical issues, non-acute abnormalities encompass inflammatory diseases affecting tendons and joints, benign tumors, tumor-like lesions, vascular abnormalities, and others. This article reviews the indispensable role of imaging in the assessment of these conditions, with a focus on plain radiography, computed tomography (CT), magnetic resonance imaging (MRI), and nuclear medicine studies, tailored to the specific clinical presentation. By providing insights into the selection and interpretation of imaging modalities, this article aims to assist clinicians in achieving accurate diagnoses and optimizing patient care for nonacute foot and ankle pathologies.

The use of non-invasive imaging modalities for the assessment of skeletal muscle quantity and quality in people with HIV: A narrative review

BACKGROUND

People with HIV (PWH) are prone to mobility impairments and physical dysfunction, with the loss of skeletal muscle quantity and quality being a major contributor to the dysfunction. Assessment of skeletal muscle is an important component of care for this patient population for early intervention and treatment. The use of non-invasive imaging techniques to evaluate skeletal muscle, such as dual X-ray absorptiometry, computer tomography and magnetic resonance imaging, has increased in popularity in recent years.

PURPOSE

This narrative review synthesizes the use of these techniques and summarizes the associations between outcomes from these imaging modalities and physical function in PWH.

Reliability of resting-state EEG modulation by continuous and intermittent theta burst stimulation of the primary motor cortex: a sham-controlled study

Theta burst stimulation (TBS) is a form of repetitive transcranial magnetic stimulation designed to induce changes of cortical excitability that outlast the period of TBS application. In this study, we explored the effects of continuous TBS (cTBS) and intermittent TBS (iTBS) versus sham TBS stimulation, applied to the left primary motor cortex, on modulation of resting state electroencephalography (rsEEG) power. We first conducted hypothesis-driven region-of-interest (ROI) analyses examining changes in alpha (8-12 Hz) and beta (13-21 Hz) bands over the left and right motor cortex. Additionally, we performed data-driven whole-brain analyses across a wide range of frequencies (1-50 Hz) and all electrodes. Finally, we assessed the reliability of TBS effects across two sessions approximately 1 month apart. None of the protocols produced significant group-level effects in the ROI. Whole-brain analysis revealed that cTBS significantly enhanced relative power between 19 and 43 Hz over multiple sites in both hemispheres. However, these results were not reliable across visits. There were no significant differences between EEG modulation by active and sham TBS protocols. Between-visit reliability of TBS-induced neuromodulatory effects was generally low-to-moderate. We discuss confounding factors and potential approaches for improving the reliability of TBS-induced rsEEG modulation.

Alveolar Cleft Size on Prenatal Two-Dimensional Ultrasonography Predicts Cleft of the Secondary Palate in Unilateral Cleft Lip

SUMMARY

Prenatal diagnosis of cleft palate (CP) is challenging. The current study's objective was to investigate whether prenatal alveolar cleft width is associated with the likelihood of a cleft of the secondary palate in unilateral cleft lip (CL). The authors reviewed two-dimensional ultrasound (US) images in fetuses with unilateral CL from January of 2012 to February of 2016. Images of the fetal face were obtained with a linear and/or curved probe in the axial and coronal planes. Measurements of the alveolar ridge gap were taken by the senior radiologist. Postnatal phenotype findings were compared with prenatal findings. Thirty patients with unilateral CL met inclusion criteria; average gestational age was 26.67 ± 5.11 weeks (range, 20.71 to 36.57 weeks). Ten fetuses were found to have an intact alveolar ridge by prenatal US; postnatal examination confirmed intact secondary palate in all. Small alveolar defects (<4 mm) were noted in three fetuses; postnatal examination documented CP in a single patient. CP was confirmed in 15 of the remaining 17 fetuses who had alveolar cleft width greater than 4 mm. An alveolar defect of greater than or equal to 4 mm on prenatal US was associated with greater likelihood of a cleft of the secondary palate [c 2 (2, n = 30) = 20.23; P < 0.001]. In the setting of unilateral CL, prenatal US documentation of alveolar defects greater than or equal to 4 mm are highly predictive of the presence of a cleft of the secondary palate. Conversely, an intact alveolar ridge is associated with an intact secondary palate.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Diagnostic, II.

Magnetic sphincter augmentation may limit access to magnetic resonance imaging

Magnetic sphincter augmentation (MSA) is an alternative surgical treatment for gastroesophageal reflux disease; however, >1.5 T magnetic resonance imaging (MRI) is contraindicated for patients who have undergone MSA with the LINX Reflux Management System (Torax Medical, Inc. Shoreview, Minnesota, USA). This drawback can impose a barrier to access of MRI, and cases of surgical removal of the device to enable patients to undergo MRI have been reported. To evaluate access to MRI for patients with an MSA device, we conducted a structured telephone interview with all diagnostic imaging providers in Arizona in 2022. In 2022, only 54 of 110 (49.1%) locations that provide MRI services had at least one 1.5 T or lower MRI scanner. The rapid replacement of 1.5 T MRI scanners by more advanced technology may limit healthcare options and create an access barrier for patients with an MSA device.

A Review of Magnetic Resonance (MR) Safety: The Essentials to Patient Safety

Nearly 40 million magnetic resonance imaging (MRI) scans are performed each year in the United States. MRI has become a relatively safe non-invasive diagnostic tool. To maintain a safe magnetic resonance (MR) environment, specific policies and safety procedures are required. The four zones of an MR site allow MR personnel to closely monitor and restrict the area. Screening patients with a questionnaire asking about implants, allergies to contrast agents, and other relevant medical information is important to safely perform an MRI scan. Providers may need to consider anesthesia for patients with claustrophobia who are unable to remain motionless. Radiologists and MR personnel need to be aware of some of the risks associated with MR and contrast agents. Safety training and knowledge of the emergency procedures in the MR environment are necessary to safely perform MR examinations.

Ferrous Illusion: A Unique Case of Welding Fume Particles Appearing as Metallic Artifacts in MRI

A rare cause of metallic artifacts over the scalp on magnetic resonance imaging (MRI) is welding fume particles that contain paramagnetic iron oxide particles. These introduce distortion of the magnetic field homogeneity and result in susceptibility artifacts. They may erroneously be reported as a pathology such as calcified lesions; therefore, awareness among radiologists is required. We report a case of a 52-year-old male, an industrial inspector by profession, who presented to the neurology clinic with headaches for which an MRI of the brain without contrast was advised. There was no brain parenchymal signal abnormality; however, numerous small rounded altered signal foci were identified along the scalp, especially in the vertex region, which returned central hypointense and marginal hyperintense signal on all sequences. The imaging signals were suspicious for calcified scalp lesions, and the patient was recalled for clinical examination, which was unremarkable for cutaneous or subcutaneous abnormality on the scalp or elsewhere over the body. A detailed history was taken retrospectively, revealing that the patient had walked through a room where welding was being done before presenting for an MRI exam, without taking a shower. The various altered signal foci over the scalp on MRI based on their shape were hence identified as welding fume particles. These were fine enough not to be visible by the naked eye but determined by the MRI machine because of their magnetic susceptibility artifact. We aim to increase radiologists' awareness of such artifacts that may be seen in patients with occupational exposure to these particles to avoid misdiagnosis of other pathologies.

The essential role of neuroimaging in diagnosing and managing cerebrovascular disease in Africa: a review

BACKGROUND

Cerebrovascular disease is a significant cause of morbidity and mortality in Africa, and using neuroimaging techniques has improved the diagnosis and management of this disease. However, there is a lack of comprehensive reviews of the role and effectiveness of neuroimaging techniques in the African context.

METHODS

We reviewed the literature to evaluate the role of neuroimaging in diagnosing and managing cerebrovascular disease in Africa. Our search included electronic databases such as PubMed, Scopus, and Google Scholar from 2000 to April 2023. We included peer-reviewed studies written in English that reported on the use of neuroimaging in diagnosing and managing cerebrovascular disease in African populations. We excluded non-peer-reviewed articles, letters, editorials, and studies unrelated to cerebrovascular disease, neuroimaging, or Africa. A total of 102 potential articles were identified; after applying our exclusion criteria and removing duplicated articles, 51 articles were reviewed.

RESULTS

Our findings suggest that neuroimaging techniques such as CT, MRI, and Skull x-ray play a crucial role in diagnosing and managing cerebrovascular disease in Africa. CT and MRI were the most commonly used techniques, with CT being more widely available and less expensive than MRI. However, challenges to using neuroimaging in Africa include the high cost of equipment and maintenance, lack of trained personnel, and inadequate infrastructure. These challenges limit the widespread use of neuroimaging in diagnosing and managing cerebrovascular disease in Africa.

CONCLUSION

Neuroimaging techniques are essential for diagnosing and managing cerebrovascular disease in Africa, but challenges to their use must be addressed to improve healthcare outcomes. Our policy recommendations can help improve the availability and accessibility of neuroimaging services in Africa.

A machine learning-based approach for RF transfer function modeling of active implantable medical electrodes at 3T MRI

Objective.The objective of this work is to propose a machine learning-based approach to rapidly and efficiently model the radiofrequency (RF) transfer function of active implantable medical (AIM) electrodes, and to overcome the limitations and drawbacks of traditional measurement methods when applied to heterogeneous tissue environments.Approach.AIM electrodes with different geometries and proximate tissue distributions were considered, and their RF transfer functions were modeled numerically. Machine learning algorithms were developed and trained with the simulated transfer function datasets for homogeneous and heterogeneous tissue distributions. The performance of the method was analyzed statistically and validated experimentally and numerically. A comprehensive uncertainty analysis was performed and uncertainty budgets were derived.Main results.The proposed method is able to predict the RF transfer function of AIM electrodes under different tissue distributions, with mean correlation coefficientsrof 0.99 and 0.98 for homogeneous and heterogeneous environments, respectively. The results were successfully validated by experimental measurements (e.g. the uncertainty of less than 0.9 dB) and numerical simulation (e.g. transfer function uncertainty <1.6 dB and power deposition uncertainty <1.9 dB). Up to 1.3 dBin vivopower deposition underestimation was observed near generic pacemakers when using a simplified homogeneous tissue model.Significance.Provide an efficient alternative of transfer function modeling, which allows a more realistic tissue distribution and the potential underestimation ofin vivoRF-induced power deposition near the AIM electrode can be reduced.

Patient Safety in MRI with the Use of a Joint-Spanning External Fixator for Knee Dislocation: A Critical Analysis Review

» Universal safety guidelines for the use of a knee-spanning external fixator in magnetic resonance imaging (MRI) are unlikely to be established considering the high variability in device construct configurations.» Per the US Food and Drug Administration, manufacturers are to provide parameters for safe MRI scanning for "MR Conditional" devices; however, such labeling may be limited in detail. Physicians should reference manufacturer labels as a starting point while making an educated clinical decision.» Scanning of a knee-spanning external fixator inside the MR bore has been safely demonstrated in previous studies, although with small sample sizes.» When considering MRI in a patient treated with a knee-spanning external fixator, physicians should use all available resources and coordinate with their medical team to make a clinically reasonable decision contrasting patient benefit vs. potential harm.

MRI safety screening of children with implants: updates and challenges

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.

New Zealand and Australian MRI technologists' (radiographers) MRI safety knowledge and confidence levels

INTRODUCTION

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.

METHOD

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.

RESULTS

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.

CONCLUSION

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.

IMPLICATIONS FOR PRACTICE

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.

Reliability of resting-state EEG modulation by continuous and intermittent theta burst stimulation of the primary motor cortex: A sham-controlled study

Theta burst stimulation (TBS) is a form of repetitive transcranial magnetic stimulation designed to induce changes of cortical excitability that outlast the period of TBS application. In this study, we explored the effects of continuous TBS (cTBS) and intermittent TBS (iTBS) versus sham TBS stimulation, applied to the primary motor cortex, on modulation of resting state electroencephalography (rsEEG) power. We first conducted hypothesis-driven region-of-interest (ROI) analyses examining changes in alpha (8-12 Hz) and beta (13-21 Hz) bands over the left and right motor cortex. Additionally, we performed data-driven whole-brain analyses across a wide range of frequencies (1-50 Hz) and all electrodes. Finally, we assessed the reliability of TBS effects across two sessions approximately 1 month apart. None of the protocols produced significant group-level effects in the ROI. Whole-brain analysis revealed that cTBS significantly enhanced relative power between 19-43 Hz over multiple sites in both hemispheres. However, these results were not reliable across visits. There were no significant differences between EEG modulation by active and sham TBS protocols. Between-visit reliability of TBS-induced neuromodulatory effects was generally low-to-moderate. We discuss confounding factors and potential approaches for improving the reliability of TBS-induced rsEEG modulation.

Should artificial intelligence be used in conjunction with Neuroimaging in the diagnosis of Alzheimer's disease?

Alzheimer's disease (AD) is a progressive, neurodegenerative disorder that affects memory, thinking, behavior, and other cognitive functions. Although there is no cure, detecting AD early is important for the development of a therapeutic plan and a care plan that may preserve cognitive function and prevent irreversible damage. Neuroimaging, such as magnetic resonance imaging (MRI), computed tomography (CT), and positron emission tomography (PET), has served as a critical tool in establishing diagnostic indicators of AD during the preclinical stage. However, as neuroimaging technology quickly advances, there is a challenge in analyzing and interpreting vast amounts of brain imaging data. Given these limitations, there is great interest in using artificial Intelligence (AI) to assist in this process. AI introduces limitless possibilities in the future diagnosis of AD, yet there is still resistance from the healthcare community to incorporate AI in the clinical setting. The goal of this review is to answer the question of whether AI should be used in conjunction with neuroimaging in the diagnosis of AD. To answer the question, the possible benefits and disadvantages of AI are discussed. The main advantages of AI are its potential to improve diagnostic accuracy, improve the efficiency in analyzing radiographic data, reduce physician burnout, and advance precision medicine. The disadvantages include generalization and data shortage, lack of in vivo gold standard, skepticism in the medical community, potential for physician bias, and concerns over patient information, privacy, and safety. Although the challenges present fundamental concerns and must be addressed when the time comes, it would be unethical not to use AI if it can improve patient health and outcome.

Physical behavior of PEDOT polymer electrode during magnetic resonance imaging and long-term test in the climate chamber

The PEDOT polymer electrode is a metal-free electrode, consisting of an acrylate (dental composite) and the conductive polymer poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). The electrode is applied as gel onto the skin and cured with blue light for 10-20 s in order to achieve a conductive bond to the skin. The electrodes are used in combination with polymer cables consisting of a textile backbone and PEDOT:PSS. To test this new electrode and cable type under different conditions we designed two stress-tests: highly sensitive temperature recordings within a head phantom during Magnetic Resonance Imaging (MRI) and long-term stability inside a climate chamber with high humidity. To study the physical behavior inside the strong magnetic field (3 Tesla), the PEDOT polymer electrode was attached to an agarose head-phantom inside a magnetic resonance tomograph during an image sequence. MRI-safe temperature sensors were placed nearby in order to measure possible heating effects. In comparison to a metal cable, nearly no rise in temperature could be observed if the electrode was used in combination with a conductive textile cable. Furthermore, the electrode showed stable impedance values inside a climate chamber for 4 consecutive days. These results pave the way for testing the PEDOT polymer electrode as biosignal recording electrode during MRI, especially for cardio MRI and Electroencephalography in combination with functional MRI (EEG-fMRI).

MRI of Lymphedema

Lymphedema is a devastating disease that has no cure. Management of lymphedema has evolved rapidly over the past two decades with the advent of surgeries that can ameliorate symptoms. MRI has played an increasingly important role in the diagnosis and evaluation of lymphedema, as it provides high spatial resolution of the distribution and severity of soft tissue edema, characterizes diseased lymphatic channels, and assesses secondary effects such as fat hypertrophy. Many different MR techniques have been developed for the evaluation of lymphedema, and the modality can be tailored to suit the needs of a lymphatic clinic. In this review article we provide an overview of lymphedema, current management options, and the current role of MRI in lymphedema diagnosis and management. EVIDENCE LEVEL: 5 TECHNICAL EFFICACY: Stage 5.

Prevalence of and risk factors for failure of fetal magnetic resonance imaging due to maternal claustrophobia or malaise

OBJECTIVE

To evaluate the prevalence of and risk factors for failure of fetal magnetic resonance imaging (MRI) due to maternal claustrophobia or malaise.

METHODS

This retrospective cohort study included pregnant women who underwent fetal MRI for clinical indications or research purposes between January 2012 and December 2019 at a single center. One group included patients who completed the entire examination and the other group inlcuded patients who interrupted their MRI examination due to claustrophobia/malaise. We estimated the rate of MRI failure due to maternal claustrophobia/malaise and compared maternal and clinical variables between the two groups. Multiple logistic regression analysis was performed to identify independent risk factors for claustrophobia/malaise during MRI examination in pregnancy.

RESULTS

Among 3413 patients who agreed to undergo fetal MRI, the prevalence of failure because of claustrophobia or malaise was 2.1%. The rate of claustrophobia/malaise in patients who underwent MRI for a clinical indication was lower compared to that in patients who underwent MRI for research purposes only (0.6% (4/696) vs 2.4% (65/2678); P = 0.003). Fetal MRI performed for research purposes only (adjusted odds ratio (aOR), 0.05 (95% CI, 0.01-0.48); P = 0.003), higher maternal age (aOR, 1.07 (95% CI, 1.02-1.12); P = 0.003) and later gestational age at the time of fetal MRI (aOR, 1.46 (95% CI, 1.16-2.04); P = 0.008) were independent risk factors for claustrophobia/malaise. Shorter fetal MRI duration (aOR, 0.77 (95% CI, 0.63-0.88); P = 0.001) was also associated with claustrophobia/malaise during the procedure. Body mass index, ethnic origin, multiple pregnancy, being parous and size of the magnetic bore were not associated with MRI failure due to claustrophobia/malaise.

CONCLUSION

The rate of fetal MRI failure due to claustrophobia or malaise was found to be low, particularly when the examination was performed for a clinical indication, and should not be considered a common problem in the pregnant population. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Assessment of MRI Safety Practices in Saudi Arabia

Aim

The aim of this study is to investigate the safety practices used by MRI departments in Saudi Arabia.

Methods

A cross-sectional study across 113 private and public hospitals was conducted in Saudi Arabia. A survey questionnaire was designed and sent to 113 MRI units. The questionnaire consisted of 43 items under 14 sections for the assessment of MRI safety practices. These 14 sections are related to (i) MRI and its safety, (ii) MRI usage and its safety, and (iii) safety of the MRI technologists and reporting of adverse effects during the usage. The American College of Radiology (ACR) guidance document on MRI safety practices was used as a template for this survey. Data were analyzed using IBM SPSS Statistical software for Windows version 26.0 (IBM Corp., Armonk, NY, USA).

Results

Of the 43 items assessed, only 3 items' binary responses (Yes & No) did not differ much. A greater proportion of positive responses for 40 items (93%) regarding MRI safety practices. More than 50% of the participants claimed that their departments lacked a Magnetic Resonance Safety Officer (MRSO). Regarding regular safety training programs, less than 50% received training in MRI safety. Handheld metal detectors were found in only 39% of the MRI units.

Conclusion

The majority of MRI units in Saudi Arabia have demonstrated compliance with majority of ACR MRI safety recommendations; nonetheless, there are two main items for which the guidelines may not be attained: MRSO and regular MRI safety training programs. By taking into account the limitations of this study, it is strongly recommended to assign MRSO and implement annual MRI safety training to improve MRI safety practices for both patients and healthcare workers.

Contrast Agents during Pregnancy: Pros and Cons When Really Needed

Many clinical conditions require radiological diagnostic exams based on the emission of different kinds of energy and the use of contrast agents, such as computerized tomography (CT), positron emission tomography (PET), magnetic resonance (MR), ultrasound (US), and X-ray imaging. Pregnant patients who should be submitted for diagnostic examinations with contrast agents represent a group of patients with whom it is necessary to consider both maternal and fetal effects. Radiological examinations use different types of contrast media, the most used and studied are represented by iodinate contrast agents, gadolinium, fluorodeoxyglucose, gastrographin, bariumsulfate, and nanobubbles used in contrast-enhanced ultrasound (CEUS). The present paper reports the available data about each contrast agent and its effect related to the mother and fetus. This review aims to clarify the clinical practices to follow in cases where a radiodiagnostic examination with a contrast medium is indicated to be performed on a pregnant patient.

A practical guide for radiographers focussing on safety during magnetic resonance imaging

Magnetic resonance imaging (MRI) poses some risk when adequate safety measures are not adhered to. Despite efforts on MRI safety, incidents still occur in MRI. Extensive training on MRI safety is essential to protect patients, staff and the public from the risks associated with magnetic fields. Safety issues in MRI include projectile and torque effects on ferromagnetic objects, thermal effects, claustrophobia and adverse reactions to contrast agents. Radiographers operating MRI scanners play a vital role in ensuring that all who enter the MRI environment adhere to the safety measures. However, radiographers are faced with challenges that impact how safety issues are monitored. This Continuing Professional Development article is aimed at highlighting these challenges and providing radiographers with some practical guidelines for these challenges.

Approach of Acromegaly during Pregnancy

Acromegaly-related sub/infertility, tidily related to suboptimal disease control (1/2 of cases), correlates with hyperprolactinemia (1/3 of patients), hypogonadotropic hypogonadism—mostly affecting the pituitary axis in hypopituitarism (10−80%), and negative effects of glucose profile (GP) anomalies (10−70%); thus, pregnancy is an exceptional event. Placental GH (Growth Hormone) increases from weeks 5−15 with a peak at week 37, stimulating liver IGF1 and inhibiting pituitary GH secreted by normal hypophysis, not by somatotropinoma. However, estrogens induce a GH resistance status, protecting the fetus form GH excess; thus a full-term, healthy pregnancy may be possible. This is a narrative review of acromegaly that approaches cardio-metabolic features (CMFs), somatotropinoma expansion (STE), management adjustment (MNA) and maternal-fetal outcomes (MFOs) during pregnancy. Based on our method (original, in extenso, English—published articles on PubMed, between January 2012 and September 2022), we identified 24 original papers—13 studies (3 to 141 acromegalic pregnancies per study), and 11 single cases reports (a total of 344 pregnancies and an additional prior unpublished report). With respect to maternal acromegaly, pregnancies are spontaneous or due to therapy for infertility (clomiphene, gonadotropins or GnRH) and, lately, assisted reproduction techniques (ARTs); there are no consistent data on pregnancies with paternal acromegaly. CMFs are the most important complications (7.7−50%), especially concerning worsening of HBP (including pre/eclampsia) and GP anomalies, including gestational diabetes mellitus (DM); the best predictor is the level of disease control at conception (IGF1), and, probably, family history of 2DM, and body mass index. STE occurs rarely (a rate of 0 to 9%); some of it symptoms are headache and visual field anomalies; it is treated with somatostatin analogues (SSAs) or alternatively dopamine agonists (DAs); lately, second trimester selective hypophysectomy has been used less, since pharmaco-therapy (PT) has proven safe. MNA: PT that, theoretically, needs to be stopped before conception—continued if there was STE or an inoperable tumor (no clear period of exposure, preferably, only first trimester). Most data are on octreotide > lanreotide, followed by DAs and pegvisomant, and there are none on pasireotide. Further follow-up is required: a prompt postpartum re-assessment of the mother’s disease; we only have a few data confirming the safety of SSAs during lactation and long-term normal growth and developmental of the newborn (a maximum of 15 years). MFO seem similar between PT + ve and PT − ve, regardless of PT duration; the additional risk is actually due to CMF. One study showed a 2-year median between hypophysectomy and pregnancy. Conclusion: Close surveillance of disease burden is required, particularly, concerning CMF; a personalized approach is useful; the level of statistical evidence is expected to expand due to recent progress in MNA and ART.

Selective MR neurography-guided anterior femoral cutaneous nerve blocks for diagnosing anterior thigh neuralgia: anatomy, technique, diagnostic performance, and patient-reported experiences

OBJECTIVE

To evaluate the clinical utility of selective magnetic resonance neurography-(MRN)-guided anterior femoral cutaneous nerve (AFCN) blocks for diagnosing anterior thigh neuralgia.

MATERIALS AND METHODS

Following institutional review board approval and informed consent, participants with intractable anterior thigh pain and clinically suspected AFCN neuralgia were included. AFCN blocks were performed under MRN guidance using an anterior groin approach along the medial sartorius muscle margin. Outcome variables included AFCN identification on MRN, technical success of perineural drug delivery, rate of AFCN anesthesia, complications, total procedure time, patient-reported procedural experiences, rate of positive diagnostic AFCN blocks, and positive subsequent treatment rate.

RESULTS

Eighteen MRN-guided AFCN blocks (six unilateral and six bilateral blocks) were performed in 12 participants (6 women; age, 49 (30-65) years). Successful MRN identified the AFCN, successful perineural drug delivery, and AFCN anesthesia was achieved in all thighs. No complications occurred. The total procedure time was 19 (10-28) min. Patient satisfaction and experience were high without adverse MRI effects. AFCN blocks identified the AFCN as the symptom generator in 16/18 (89%) cases, followed by 14/16 (88%) successful treatments.

CONCLUSION

Our results suggest that selective MR neurography-guided AFCN blocks effectively diagnose anterior femoral cutaneous neuralgia and are well-tolerated.

Perceived safety of MRI units in the two public hospitals within the central region of South Africa: A pilot study among four MR staff

Magnetic resonance scanners are considered safe but comes with substantive safety risks to patients seeking radiological diagnostics and health care professionals. This pilot study aimed to assess the safety compliance of MRI units commonly used in the clinical diagnostic imaging of two public hospitals in South Africa. Structured interviews were conducted with four MRI staff assigned to work in the 1.5 and 3.0 T MRI units. Their responses were benchmarked with ACR MR Safety guideline of 2019 to assess any safety compliance deviations. Thematic analysis was conducted by evaluating responses per themes and further expanding on comments provided on Yes or No options. There were few major shortfalls identified that include outdated safety policies, inadequate screening, nonexistence of demarcations and lack of training of MR and non-MR personnel of MRI safety. These challenges could be eliminated by introducing a comprehensive occupational health and safety program, specific to the MRI units.

Parameters Affecting Worst-Case Gradient-Field Heating of Passive Conductive Implants

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.

The Effect on the Germination Vigour of Cucumber Seeds after Receiving Magnetic Field Treatment Pre-Sowing

In the experiment, the impact of magnetisation on cucumber seeds is examined with the use of Bitter magnets with a constant magnetic field. The magnetisation process is performed in three magnetic fields: low—200 mT, medium—1 T, and high—9 T for 15 and 60 min. After germination, the biometric parameters are determined. The results of this research show that cucumber after pre-treatment in a magnetic field of 1 T for 60 min has a similar germination capacity and root length as the control sample. However, cucumber seeds magnetised in a 1 T field for 60 min have a significantly higher dry weight than the control sample (5.50 ± 0.32 mg vs. 3.01 ± 0.18 mg). The magnetisation in 9 T for both 15 and 60 min shows that these samples have a significantly lower germination capacity (86.8 ± 4.4% and 81.4 ± 7.3% vs. 91.8 a ± 3.2%) and root length (1.78 ± 0.02 cm and 4.42 ± 0.83 cm vs. 8.21 ± 0.34 cm) compared to the control sample. The cucumber seeds pre-treated at 9 T have a significantly greater dry weight than the control sample. Additionally, our research shows that some magnetic field intensities and magnetisation durations inhibit root growth and limit germination. These results are also important as they indicate which values of magnetic fields should be avoided.

Neuroimaging in the Era of Artificial Intelligence: Current Applications

BACKGROUND

Artificial intelligence (AI) in medicine has shown significant promise, particularly in neuroimaging. AI increases efficiency and reduces errors, making it a valuable resource for physicians. With the increasing amount of data processing and image interpretation required, the ability to use AI to augment and aid the radiologist could improve the quality of patient care.

OBSERVATIONS

AI can predict patient wait times, which may allow more efficient patient scheduling. Additionally, AI can save time for repeat magnetic resonance neuroimaging and reduce the time spent during imaging. AI has the ability to read computed tomography, magnetic resonance imaging, and positron emission tomography with reduced or without contrast without significant loss in sensitivity for detecting lesions. Neuroimaging does raise important ethical considerations and is subject to bias. It is vital that users understand the practical and ethical considerations of the technology.

CONCLUSIONS

The demonstrated applications of AI in neuroimaging are numerous and varied, and it is reasonable to assume that its implementation will increase as the technology matures. AI's use for detecting neurologic conditions holds promise in combatting ever increasing imaging volumes and providing timely diagnoses.

Recent development of a magneto-optical nanoplatform for multimodality imaging of pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is the most common type of pancreatic cancer. Given its inconspicuous and atypical early symptoms and hidden location, most patients have already reached the terminal stage before diagnosis. At present, the diagnosis of PDAC mainly depends on serological and imaging examinations. However, serum tests cannot identify specific tumor locations and each imaging technology has its own defects, bringing great challenges to the early diagnosis of PDAC. Therefore, it is of great significance to find new strategies for the early and accurate diagnosis of PDAC. In recent years, a magneto-optical nanoplatform integrating near infrared fluorescence, photoacoustic, magnetic resonance imaging, etc. has attracted widespread attention, giving full play to the complementary advantages of each imaging modality. Herein, we summarize the recent advances of imaging modalities in the diagnosis of pancreatic cancer, and then discuss in detail the construction and modification of magneto or/and optical probes for multimodal imaging, and advances in early diagnosis using the combination of various imaging modalities, which can provide potential tools for the early diagnosis or even intraoperative navigation and post-treatment follow-up of PDAC patients.

Management of Patients With Common Bile Duct Dilatation Without a Sonographic Evident Cause: Evaluating the Yield of Subsequent Magnetic Resonance Imaging and Findings Correlated With Causative Pancreaticobiliary Pathology

OBJECTIVES

The aims of the study were to evaluate the yield of magnetic resonance imaging (MRI) in patients with common bile duct (CBD) dilatation without a sonographic evident cause and to investigate sonographic and laboratory findings at presentation that might predict identification of underlying pancreaticobiliary pathology.

METHODS

Included were consecutive patients in whom MRI was performed for further evaluation of CBD dilatation detected on ultrasound (US), without a sonographic evident cause, from January 1, 2014, to December 31, 2014. Magnetic resonance imaging and clinical data were retrospectively reviewed. Patients were divided into two groups: patients with and without identified underlying causative pancreaticobiliary pathology. Ultrasound findings and laboratory results at presentation were compared between groups to identify findings suggestive of underlying pancreaticobiliary pathology.

RESULTS

Fifty-seven patients, with a mean age of 54 ± 16 years including 37 females (65%), underwent MRI. Specific pancreaticobiliary causes for CBD dilatation were identified in 38 patients (66%, 31 benign and 7 malignant). In the remaining patients, no cause was identified in 17 (30%) and MRIs were nondiagnostic in 2 patients. Magnetic resonance imaging accuracy for correctly identifying the underlying cause of CBD dilatation was 91%. Patients with associated intrahepatic bile duct dilatation on US and elevated alanine aminotransferase and alkaline phosphatase were more likely to have underlying pancreaticobiliary pathology (P < 0 .05). No patient with initial negative MRI had pancreaticobiliary malignancy.

CONCLUSIONS

Magnetic resonance imaging seems to be an accurate noninvasive method for identifying the underlying cause in most patients with CBD dilatation on US and in excluding pancreaticobiliary malignancy. Patients with associated intrahepatic bile duct dilatation and/or elevated liver enzymes are at higher risk of harboring underlying pancreaticobiliary pathology.

Evaluation of hearing loss in young adults after exposure to 3.0T MRI with standard hearing protection

Standard clinical protocols require hearing protection during magnetic resonance imaging (MRI) for patient safety. This investigation prospectively evaluated the auditory function impact of acoustic noise exposure during a 3.0T MRI in healthy adults. Twenty-nine participants with normal hearing underwent a comprehensive audiologic assessment before and immediately following a clinically indicated head MRI. Appropriate hearing protection with earplugs (and pads) was used per standard of practice. To characterize noise hazards, current sound monitoring tools were used to measure levels of pulse sequences measured. A third audiologic test was performed if a significant threshold shift (STS) was identified at the second test, within 30 days post MRI. Some sequences produced high levels (up to 114.5 dBA; 129 dB peak SPL) that required hearing protection but did not exceed 100% daily noise dose. One participant exhibited an STS in the frequency region most highly associated with noise-induced hearing loss. No participants experienced OSHA-defined STS in either ear. Overall, OAE measures did not show evidence of changes in cochlear function after MRI. In conclusion, hearing threshold shifts associated with hearing loss or OAE level shifts reflecting underlying cochlear damage were not detected in any of the 3.0T MRI study participants who used the current recommended hearing protection.

An integrated TMS-EEG and MRI approach to explore the interregional connectivity of the default mode network

Explorations of the relation between brain anatomy and functional connections in the brain are crucial for shedding more light on network connectivity that sustains brain communication. In this study, by means of an integrative approach, we examined both the structural and functional connections of the default mode network (DMN) in a group of sixteen healthy subjects. For each subject, the DMN was extracted from the structural and functional resonance imaging data; the areas that were part of the DMN were defined as the regions of interest. Then, the target network was structurally explored by diffusion-weighted imaging, tested by neurophysiological means, and retested by means of concurrent transcranial magnetic stimulation and electroencephalography (TMS-EEG). A series of correlational analyses were performed to explore the relationship between the amplitude of early-latency TMS-evoked potentials and the indexes of structural connectivity (weighted number of fibres and fractional anisotropy). Stimulation of the left or right parietal nodes of the DMN-induced activation in the contralateral parietal and frontocentral electrodes within 60 ms; this activation correlated with fractional anisotropy measures of the corpus callosum. These results showed that distant secondary activations after target stimulation can be predicted based on the target’s anatomical connections. Interestingly, structural features of the corpus callosum predicted the activation of the directly connected nodes, i.e., parietal-parietal nodes, and of the broader DMN network, i.e., parietal-frontal nodes, as identified with functional magnetic resonance imaging. Our results suggested that the proposed integrated approach would allow us to describe the contributory causal relationship between structural connectivity and functional connectivity of the DMN.

Magnetic particles in motion: magneto-motive imaging and sensing

Superparamagnetic nanoparticles have become an important tool in biomedicine. Their biocompatibility, controllable small size, and magnetic properties allow manipulation with an external magnetic field for a variety of diagnostic and therapeutic applications. Recently, the magnetically-induced motion of superparamagnetic nanoparticles has been investigated as a new source of imaging contrast. In magneto-motive imaging, an external, time-varying magnetic field is applied to move a magnetically labeled subject, such as labeled cells or tissue. Several major imaging modalities such as ultrasound, photoacoustic imaging, optical coherence tomography, and laser speckle tracking can utilize magneto-motive contrast to monitor biological events at smaller scales with enhanced contrast and sensitivity. In this review article, an overview of magneto-motive imaging techniques is presented, including synthesis of superparamagnetic nanoparticles, fundamental principles of magneto-motive force and its utility to excite labeled tissue within a viscoelastic medium, current capabilities of magneto-motive imaging modalities, and a discussion of the challenges and future outlook in the magneto-motive imaging domain.

MRI in Pregnancy and Precision Medicine: A Review from Literature

Magnetic resonance imaging (MRI) offers excellent spatial and contrast resolution for evaluating a wide variety of pathologies, without exposing patients to ionizing radiations. Additionally, MRI offers reproducible diagnostic imaging results that are not operator-dependent, a major advantage over ultrasound. MRI is commonly used in pregnant women to evaluate, most frequently, acute abdominal and pelvic pain or placental abnormalities, as well as neurological or fetal abnormalities, infections, or neoplasms. However, to date, our knowledge about MRI safety during pregnancy, especially about the administration of gadolinium-based contrast agents, which are able to cross the placental barrier, is still limited, raising concerns about possible negative effects on both the mother and the health of the fetus. Contrast agents that are unable to cross the placenta in a way that is safe for the fetus are desirable. In recent years, some preclinical studies, carried out in rodent models, have evaluated the role of long circulating liposomal nanoparticle-based blood-pool gadolinium contrast agents that do not penetrate the placental barrier due to their size and therefore do not expose the fetus to the contrast agent during pregnancy, preserving it from any hypothetical risks. Hence, we performed a literature review focusing on contrast and non-contrast MRI use during pregnancy.

A National Survey on Safety Management at MR Imaging Facilities in Japan

PURPOSE

To investigate safety management at Japanese facilities performing human MRI studies.

METHODS

All Japanese facilities performing human MRI studies were invited to participate in a comprehensive survey that evaluated their MRI safety management. The survey used a questionnaire prepared with the cooperation of the Safety Committee of the Japanese Society for Magnetic Resonance in Medicine. The survey addressed items pertaining to the overall MRI safety management, questions on the occurrence of incidents, and questions specific to facility and MRI scanner or examination. The survey covered the period from October 2017 to September 2018. Automated machine learning was used to identify factors associated with major incidents.

RESULTS

Of 5914 facilities, 2015 (34%) responded to the questionnaire. There was a wide variation in the rate of compliance with MRI safety management items among the participating facilities. Among the facilities responding to this questionnaire, 5% reported major incidents and 27% reported minor incidents related to MRI studies. Most major incidents involved the administration of contrast agents. The most influential factor in major incidents was the total number of MRI studies performed at the facility; this number was significantly correlated with the risk of major incidents (P < 0.0001).

CONCLUSION

There were large variations in the safety standards applied at Japanese facilities performing clinical MRI studies. The total number of MRI studies performed at a facility affected the number of major incidents.