Biological effects and safety in magnetic resonance imaging: a review

An automated pipeline for computation and analysis of functional ventilation and perfusion lung MRI with matrix pencil decomposition: TrueLung

PURPOSE

To introduce and evaluate TrueLung, an automated pipeline for computation and analysis of free-breathing and contrast-agent free pulmonary functional magnetic resonance imaging.

MATERIALS AND METHODS

Two-dimensional time-resolved ultra-fast balanced steady-state free precession acquisitions were transferred to TrueLung, which included image quality checks, image registration, and computation of perfusion and ventilation maps with matrix pencil decomposition. Neural network whole-lung and lobar segmentations allowed quantification of impaired relative perfusion (RQ) and fractional ventilation (RFV). TrueLung delivered functional maps and quantitative outcomes, reported for clinicians in concise documents. We evaluated the pipeline using 1.5T data from 75 children with cystic fibrosis by assessing the feasibility of functional MR imaging, average scan time, and the robustness of the functional outcomes. Whole-lung and lobar segmentations were manually refined when necessary, and the impact on RQ and RFV was quantified.

RESULTS

Functional imaging was feasible in all included CF children without any dropouts. On average, 7.9 ± 1.8 (mean±SD) coronal slice positions per patient were acquired, resulting in a mean scan time of 6min 20s per patient. The whole pipeline required 20min processing time per subject. TrueLung delivered the functional maps of all the subjects for radiological assessment. Quality controlling maps and segmentations lasted 1min 12s per patient. The automated segmentations and quantification of whole-lung defects were satisfying in 88% of patients (97% of slices) and the lobar quantification in 73% (93% of slices). The segmentations refinements required 16s per patient for the whole-lung, and 2min 10s for the lobe masks. The relative differences in RFV and RQ between fully-automated and manually refined data were 0.7% (1.2%) and 2.0% (2.9%) for whole-lung quantification (median, [third quartile]), and excluding two outliers, 1.7% (3.9%) and 1.2% (3.8%) for the lobes, indicating the refinements could be potentially omitted in several patients.

CONCLUSIONS

TrueLung quickly delivers functional maps and quantitative outcomes in an objective and standardized way, suitable for radiological and pneumological assessment with minimal manual input. TrueLung can be used for clinical research in cystic fibrosis and might be applied across various lung diseases.

Evolving Radiological Approaches in the Diagnosis and Monitoring of Arachnoiditis Ossificans

Arachnoiditis ossificans (AO) is a rare and complex neurological condition characterized by pathological calcification or ossification of the arachnoid membrane. Arachnoiditis ranks as the third most frequent cause of failed back surgery syndrome (FBSS). This narrative review explores the evolving radiological approaches in its diagnosis and monitoring. The historical perspective traces the progression from plain radiographs to advanced imaging techniques. Current radiological modalities, including X-ray, computed tomography (CT), and magnetic resonance imaging (MRI), are discussed, highlighting their respective roles, advantages, and limitations. Emerging and advanced imaging modalities, such as high-resolution CT, 3T and 7T MRI, and PET/CT or PET/MRI, are examined for their potential to enhance diagnostic accuracy and monitoring capabilities. A comparative analysis of these imaging modalities considers their sensitivity, specificity, cost-effectiveness, and radiation exposure implications. The review also explores the crucial role of imaging in disease monitoring and treatment planning, including follow-up protocols, evaluation of disease progression, and guidance for interventional procedures. Future directions in the field are discussed, focusing on promising research areas, the potential of artificial intelligence and machine learning in image analysis, and identified gaps in current knowledge. The review emphasizes the importance of a multimodal imaging approach and the need for standardized protocols. It concludes that while significant advancements have been made, further research is necessary to fully understand the correlation between imaging findings and clinical outcomes. The continued evolution of radiological approaches is expected to significantly improve patient care and outcomes in AO.

Integrative approach of omics and imaging data to discover new insights for understanding brain diseases

Treatments that can completely resolve brain diseases have yet to be discovered. Omics is a novel technology that allows researchers to understand the molecular pathways underlying brain diseases. Multiple omics, including genomics, transcriptomics and proteomics, and brain imaging technologies, such as MRI, PET and EEG, have contributed to brain disease-related therapeutic target detection. However, new treatment discovery remains challenging. We focused on establishing brain multi-molecular maps using an integrative approach of omics and imaging to provide insights into brain disease diagnosis and treatment. This approach requires precise data collection using omics and imaging technologies, data processing and normalization. Incorporating a brain molecular map with the advanced technologies through artificial intelligence will help establish a system for brain disease diagnosis and treatment through regulation at the molecular level.

Impacts of 1.5 T MRI Static Magnetic Field on Biochemical and Enzyme Activity Parameters on Radiology Department Workers

Magnetic Resonance Imaging (MRI) is an important diagnostic technique that uses powerful magnetic fields to generate detailed images of the human body. The aim of this study is to investigate to how static magnetic fields (SMF) affect the levels of trace elements and biochemical parameters in MRI staff' blood serum. This study examines the impacts of these exposures of 18 participants (9 males and 9 females) aged between 25 and 60.on the levels of trace elements in the blood serum and the biochemical parameters of the MRI staff at Azadi Teaching Hospital in Duhok and Zakho General Hospital-Bidari in Zakho City. Eighteen participants, consisting of nine males and nine females aged between 25 and 60, were selected from these hospitals. The researchers obtained blood samples and conducted analysis to determine the presence of trace elements (sodium, potassium, calcium, chloride) as well as numerous biochemical markers. The results showed that potassium and calcium levels increased with age, and older females had considerable deviations. Chloride levels exhibited a significant increase with age in both males and females. Glucose, creatinine, uric acid, and urea levels showed an increase with age, suggesting the possible damage to kidney function caused by continuous exposure to MRI. Increased levels of liver enzymes (GPT, GOT, ALP) and thyroid-stimulating hormone (TSH) were noticed, particularly in older females, indicating potential liver and thyroid dysfunction. These results highlight the importance of applying strict safety protocols and conducting regular health assessments for MRI personnel to minimize the possible hazards.

Mixed shift rotations, sleep, burnout and well-being in professions similar to radiographers: A systematic review

INTRODUCTION

Delivering 24 h healthcare requires rotational shift work from doctors and the medical imaging team, while contributing to safe and timely care of patients. Additional service pressure and staff shortfall leads to workload pressures, adjusted shift patterns and risk of burnout. Evidence should be sought to the effects of this work on staff.

METHODS

This systematic review followed PRISMA reporting guidelines, using a convergent mixed methods approach according to Guidance from Joanna Briggs International. Quantitative trends and results were qualified in order to thematically analyse in conjunction with qualitative data and discussed together in context. Following initial searching, returned articles were screened by title and abstract. A team of 3 reviewers undertook blinded critical appraisal of those suitable, with quality assurance from a 4th team member. Papers passing a threshold of 75% on JBI appraisal tools were accepted for synthesis. Data extraction of appropriate articles retrieved was undertaken in parallel.

RESULTS

Following screening and critical appraisal, 13 studies were returned focusing exclusively on Non Consultant Doctors. No studies investigated diagnostic radiographers. 85% (n = 11) reported negative association between shift work and the three themes of sleep/fatigue, burnout and wellbeing: including after the introduction of shift pattern control or adjusted shift patterns. The remainder showed no change, or any improvement nullified by countermeasures to maintain service delivery.

CONCLUSION

Current working practices and shift plans in the target population showed detrimental effects on the participants - this can be suggested that Diagnostic Radiographers may suffer fatigue, burnout and poor mental health from stretched shift working patterns.

IMPLICATIONS FOR PRACTICE

Further study into the effects of shift work on Diagnostic Radiographers and other allied health professionals is indicated - relating to the above themes in the context of errors and patient safety. Additional research into Non Consultant Doctors, shift work effects and the context of wider service delivery required; with suitable interventions and education to maximise understanding of legal working practices, monitoring and self-management of symptoms.

Perceptions of Risk, Benefit and Trust - A Comparative Assessment Between Healthcare Workers and the General Public Towards 3 Medical Technologies

Background and Objective

While there is a substantial amount of research on risk perception, there has been less focus on the way medical technologies are perceived by experts as opposed to lay individuals. We investigated the factors that may influence the risk perception of healthcare workers (HCWs) and the general public regarding 3 distinct medical technologies: magnetic resonance imaging (MRI), laser-assisted in situ keratomileusis (LASIK) and the Covid-19 vaccine.

Methods

A cross-sectional study conducted in 2021 among 2 populations: HCWs employed at a general public hospital and a sample of outpatients and individuals who are not medical professionals. The participants completed an electronic questionnaire.

Results

In total, 739 respondents were included: 197 HCWs (26.7%) and 542 members of the public (73.3%). Most of the respondents (89.4%) reported being vaccinated against Covid-19, 43.8% had previously undergone an MRI but 90% had not undergone LASIK. Overall, all 3 technologies assessed in the study were rated by the respondents as having a high benefit and low risk. HCWs and the public showed statistically significant differences in perceived risk towards MRI and LASIK, as well as in some of the risk perception characteristics of each technology. In contrast, no differences in risk perception towards the Covid-19 vaccine were found between HCWs and the public. Both study populations showed a significant negative correlation between trust in the MoH and the perceived risk towards MRI and the Covid-19 vaccine. Both study populations regarded information provided by medical sources as the most reliable for decision-making.

Conclusion

The perceptions and concerns towards medical technologies influence individuals' behavior and acceptance of technologies. They are also essential for risk communication. The study contributes to the understanding of attitudes towards various medical technologies, including risk perception, risk characteristics, trust and sources of information pertaining to each of the technologies, by examining the differences between HCWs and the general public.

Three-dimensional imaging evaluation of facial swelling after orthognathic surgery with compression and Kinesio taping therapy: a randomized clinical trial

Background

Postoperative swelling is a common complication of orthognathic surgery. The authors used three-dimensional (3D) image analysis and body surface temperature to determine the effects of compression taping (CT) and Kinesio taping (KT) by the epidermis, dermis, and fascia method (EDF-KT) on postoperative swelling.

Materials and methods

The authors conducted a prospective, parallel-group, randomized controlled trial. Among the 162 patients diagnosed with jaw deformity and who underwent orthognathic surgery from August 2020 to October 2022, 105 patients (men: 36, women: 69, mean age: 28.27±8.92) underwent Le Fort type I + sagittal split ramus osteotomy (SSRO) or SSRO and were included in this study. Patients were randomly divided into three groups: EDF-KT group (n=31), CT group (n=41), and no tape group (control group, n=30). All taping was performed immediately postoperatively and removed on postoperative day (POD) 5. Three-dimensional images of the participants' faces were obtained preoperatively and at PODs 3, 7, 30, and 90 using a hand-held 3D imaging system and infrared thermography.

Results

No significant difference was observed in postoperative swelling and postoperative body surface temperature between the groups at each time point. The CT group showed a trend towards reduced swelling on PODs 3 and 7 and a trend toward residual swelling on POD 90. The EDF-KT group showed a trend towards an increase in postoperative body surface temperature.

Conclusion

CT taping may not be appropriate for postoperative swelling control, suggesting that EDF-KT may affect body surface temperature. Further validation of the efficacy of KT for jaw deformities is needed.

Ultra-high static magnetic field induces a change in the spectrum but not frequency of DNA spontaneous mutations in Arabidopsis thaliana

Biological effects of magnetic fields have been extensively studied in plants, microorganisms and animals, and applications of magnetic fields in regulation of plant growth and phytoprotection is a promising field in sustainable agriculture. However, the effect of magnetic fields especially ultra-high static magnetic field (UHSMF) on genomic stability is largely unclear. Here, we investigated the mutagenicity of 24.5, 30.5 and 33.0 T UHSMFs with the gradient of 150, 95 and 0 T/m, respectively, via whole genome sequencing. Our results showed that 1 h exposure of Arabidopsis dried seeds to UHSMFs has no significant effect on the average rate of DNA mutations including single nucleotide variations and InDels (insertions and deletions) in comparison with the control, but 33.0 T and 24.5 T treatments lead to a significant change in the rate of nucleotide transitions and InDels longer than 3 bp, respectively, suggesting that both strength and gradient of UHSMF impact molecular spectrum of DNA mutations. We also found that the decreased transition rate in UHSMF groups is correlated with the upstream flanking sequences of G and C mutation sites. Furthermore, the germination rate of seeds exposed to 24.5 T SMF with -150 T/m gradient showed a significant decrease at 24 hours after sowing. Overall, our data lay a basis for precisely assessing the potential risk of UHSMF on DNA stability, and for elucidating molecular mechanism underlying gradient SMF-regulated biological processes in the future.

FP-CNN: Fuzzy pooling-based convolutional neural network for lung ultrasound image classification with explainable AI

The COVID-19 pandemic wreaks havoc on healthcare systems all across the world. In pandemic scenarios like COVID-19, the applicability of diagnostic modalities is crucial in medical diagnosis, where non-invasive ultrasound imaging has the potential to be a useful biomarker. This research develops a computer-assisted intelligent methodology for ultrasound lung image classification by utilizing a fuzzy pooling-based convolutional neural network FP-CNN with underlying evidence of particular decisions. The fuzzy-pooling method finds better representative features for ultrasound image classification. The FPCNN model categorizes ultrasound images into one of three classes: covid, disease-free (normal), and pneumonia. Explanations of diagnostic decisions are crucial to ensure the fairness of an intelligent system. This research has used Shapley Additive Explanation (SHAP) to explain the prediction of the FP-CNN models. The prediction of the black-box model is illustrated using the SHAP explanation of the intermediate layers of the black-box model. To determine the most effective model, we have tested different state-of-the-art convolutional neural network architectures with various training strategies, including fine-tuned models, single-layer fuzzy pooling models, and fuzzy pooling at all pooling layers. Among different architectures, the Xception model with all pooling layers having fuzzy pooling achieves the best classification results of 97.2% accuracy. We hope our proposed method will be helpful for the clinical diagnosis of covid-19 from lung ultrasound (LUS) images.

Bone marrow lesions: plugging the holes in our knowledge using animal models

Bone marrow lesions (BMLs), which are early signs of osteoarthritis (OA) that are associated with the presence, onset and severity of pain, represent an emerging imaging biomarker and clinical target. Little is known, however, regarding their early spatial and temporal development, structural relationships or aetiopathogenesis, because of the sparsity of human early OA imaging and paucity of relevant tissue samples. The use of animal models is a logical approach to fill the gaps in our knowledge, and it can be informed by appraising models in which BMLs and closely related subchondral cysts have already been reported, including in spontaneous OA and pain models. The utility of these models in OA research, their relevance to clinical BMLs and practical considerations for their optimal deployment can also inform medical and veterinary clinicians and researchers alike.

Nanomedicine and nanobiotechnology applications of magnetoelectric nanoparticles

Unlike any other nanoparticles known to date, magnetoelectric nanoparticles (MENPs) can generate relatively strong electric fields locally via the application of magnetic fields and, vice versa, have their magnetization change in response to an electric field from the microenvironment. Hence, MENPs can serve as a wireless two-way interface between man-made devices and physiological systems at the molecular level. With the recent development of room-temperature biocompatible MENPs, a number of novel potential medical applications have emerged. These applications include wireless brain stimulation and mapping/recording of neural activity in real-time, targeted delivery across the blood-brain barrier (BBB), tissue regeneration, high-specificity cancer cures, molecular-level rapid diagnostics, and others. Several independent in vivo studies, using mice and nonhuman primates models, demonstrated the capability to deliver MENPs in the brain across the BBB via intravenous injection or, alternatively, bypassing the BBB via intranasal inhalation of the nanoparticles. Wireless deep brain stimulation with MENPs was demonstrated both in vitro and in vivo in different rodents models by several independent groups. High-specificity cancer treatment methods as well as tissue regeneration approaches with MENPs were proposed and demonstrated in in vitro models. A number of in vitro and in vivo studies were dedicated to understand the underlying mechanisms of MENPs-based high-specificity targeted drug delivery via application of d.c. and a.c. magnetic fields. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Nanomedicine for Neurological Disease Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Enhanced effect of X-rays in the presence of a static magnetic field within a 3D pancreatic cancer model

OBJECTIVE

To evaluate the impact of static magnetic field (SMF) presence on the radiation response of pancreatic cancer cells in polyurethane-based highly macro-porous scaffolds in hypoxic (1% O2) and normoxic (21% O2) conditions, towards understanding MR-guided radiotherapy, shedding light on the potential interaction phenomenon between SMF and radiation in a three-dimensional (3D) microenvironment.

METHODS

Pancreatic cancer cells (PANC-1, ASPC-1) were seeded into fibronectin-coated highly porous polyethene scaffolds for biomimicry and cultured for 4 weeks in in vitro normoxia (21% O2) followed by a 2-day exposure to either in vitro hypoxia (1% O2) or maintenance in in vitro normoxia (21% O2). The samples were then irradiated with 6 MV photons in the presence or absence of a 1.5 T field. Thereafter, in situ post-radiation monitoring (1 and 7 days post-irradiation treatment) took place via quantification of (i) live dead and (ii) apoptotic profiles.

RESULTS

We report: (i) pancreatic ductal adenocarcinoma hypoxia-associated radioprotection, in line with our previous findings, (ii) an enhanced effect of radiation in the presence of SMFin in vitro hypoxia (1% O2) for both short- (1 day) and long-term (7 days) post -radiation analysis and (iii) an enhanced effect of radiation in the presence of SMF in in vitro normoxia (21% O2) for long-term (7 days) post-radiation analysis within a 3D pancreatic cancer model.

CONCLUSION

With limited understanding of the potential interaction phenomenon between SMF and radiation, this 3D system allows combination evaluation for a cancer in which the role of radiotherapy is still evolving.

ADVANCES IN KNOWLEDGE

This study examined the use of a 3D model to investigate MR-guided radiotherapy in a hypoxic microenvironment, indicating that this could be a useful platform to further understanding of SMF influence on radiation.

Safety Survey on Lone Working Magnetic Resonance Imaging Technologists in Saudi Arabia

PURPOSE

The American College of Radiology (ACR) requires MR personnel not to work alone due to the increased risk of safety issues such as projectiles, aggressive patients, and technologist fatigue. As a result, we intend to assess the current safety of lone-working MRI technologists in MRI departments in Saudi Arabia.

MATERIALS AND METHODS

A cross-sectional study using a self-report questionnaire was conducted in 88 Saudi hospitals.

RESULTS

A response rate of 64% (174/270) was obtained among the 270 MRI technologists which were identified. The study discovered that 86% of MRI technologists had prior experience working alone. In terms of MRI safety training, 63% of MRI technologists received such training. A question about lone MRI workers' awareness of the ACR's recommendations revealed that 38% were unaware of such recommendations. Furthermore, 22% were misinformed, believing that working alone in an MRI unit is optional or depends on the individual's desire to work alone. Working alone has the primary consequence of being statistically significantly associated with projectile/object-related accidents/mistakes (p = 0.03).

CONCLUSION

Saudi Arabian MRI technologists have extensive experience working alone without supervision. Most MRI technologists are unaware of lone working regulations, which has raised concerns about accidents/mistakes. There is a need for MRI safety training and adequate practical experience to raise awareness of MRI safety regulations and policies related to lone working among departments and MRI workers.

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.

The reliability of video fluoroscopy, ultrasound imaging, magnetic resonance imaging and radiography for measurements of lumbar spine segmental range of motion in-vivo: A review

BACKGROUND

Lower back pain (LBP) is a principal cause of disability worldwide and is associated with a variety of spinal conditions. Individuals presenting with LBP may display changes in spinal motion. Despite this, the ability to measure lumbar segmental range of motion (ROM) non-invasively remains a challenge.

OBJECTIVE

To review the reliability of four non-invasive modalities: Video Fluoroscopy (VF), Ultrasound imaging (US), Magnetic Resonance Imaging (MRI) and Radiography used for measuring segmental ROM in the lumbar spine in-vivo.

METHODS

The methodological quality of seventeen eligible studies, identified through a systematic literature search, were appraised.

RESULTS

The intra-rater reliability for VF is excellent in recumbent and upright positions but errors are larger for intra-rater repeated movements and inter-rater reliability shows larger variation. Excellent results for intra- and inter-rater reliability are seen in US studies and there is good reliability within- and between-day. There is a large degree of heterogeneity in MRI and radiography methodologies but reliable results are seen.

CONCLUSIONS

Excellent reliability is seen across all modalities. However, VF and radiography are limited by radiation exposure and MRI is expensive. US offers a non-invasive, risk free method but further research must determine whether it yields truly consistent measurements.

Renal imaging at 5 T versus 3 T: a comparison study

Background

Recently, a whole-body 5 T MRI scanner was developed to open the door of abdominal imaging at high-field strength. This prospective study aimed to evaluate the feasibility of renal imaging at 5 T and compare the image quality, potential artifacts, and contrast ratios with 3 T.

Methods

Forty healthy volunteers underwent MRI examination both at 3 T and 5 T. MRI sequences included T1-weighted gradient-echo (GRE), T2-weighted fast spin echo, diffusion-weighted imaging, and multi-echo GRE T2* mapping. Image quality and presence of artifacts were assessed for all sequences using four-point scales. For anatomical imaging, the signal-to-noise ratio (SNR) and contrast ratio (CR) of abdomen organ tissues were calculated. Besides, for functional imaging, the contrast-to-noise ratio of cortex/medulla was calculated. Wilcoxon signed rank-sum test was used to compare the visual evaluation scores and quantitative measurements between 3 and 5 T images.

Results

Compared to 3 T examination, T1-weighted sequence at 5 T showed significantly better image quality with higher conspicuity of the renal veins and arteries, and comparable artifacts. Image quality was comparable between both field strengths on T2-weighted images, whereas a significantly higher level of artifacts was observed at 5 T. Besides, 5 T MRI contributed to higher SNR and CR for abdomen organ tissues. For functional imaging, 5 T MRI showed improved corticomedullar discrimination. There was no significant difference between apparent diffusion coefficient of renal at 3 T and 5 T, while 5 T MRI resulted in significantly shorter T2* values in both cortex and medulla.

Conclusions

5 T MRI provides anatomical and functional images of the kidney with sufficient image quality.

Evaluation of dual-energy X-ray absorptiometry compared to magnetic resonance imaging for collecting measurements of the human bony pelvis

OBJECTIVES

Imaging methods to measure the human pelvis in vivo provide opportunities to better understand pelvic variation and adaptation. Magnetic resonance imaging (MRI) provides high-resolution images, but is more expensive than dual-energy X-ray absorptiometry (DXA). We sought to compare pelvic breadth measurements collected from the same individuals using both methods, to investigate if there are systematic differences in pelvic measurement between these imaging methods.

METHODS

Three pelvic breadth dimensions (bi-iliac breadth, bi-acetabular breadth, medio-lateral inlet breadth) were collected from MRI and DXA scans of a cross-sectional sample of healthy, nulliparous adult women of South Asian ancestry (n = 63). Measurements of MRI and DXA pelvic dimensions were collected four times in total, with one baseline data collection session and three replications. Data collected from these sessions were averaged, used to calculate technical error of measurement and entered into a Bland-Altman analysis. Linear regression models were fitted with a given MRI pelvic measurement regressed on the same measurement collected from DXA scans, as well as MRI mean bias regressed on DXA mean bias.

RESULTS

Technical error of measurement was higher in DXA measurements of bi-iliac breadth and medio-lateral pelvic inlet breadth and higher for MRI measurements of bi-acetabular breadth. Bland Altman analyses showed no statistically significant relationship between the mean bias of MRI and DXA, and the differences between MRI and DXA pelvic measurements.

CONCLUSIONS

DXA measurements of pelvic breadth are comparable to MRI measurements of pelvic breadth. DXA is a less costly imaging technique than MRI and can be used to collect measurements of skeletal elements in living people.

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.

Effects of 10 T static magnetic field on the function of sperms and their offspring in Caenorhabditis elegans

With the wide application of static magnetic fields (SMFs), the risk of living organisms exposed to man-made magnetic fields that the intensity is much higher than geomagnetic field has gradually increased. Reproductive system is highly sensitive to environmental stress; however, the influence of high SMFs on reproduction system is still largely unknown. Here we explored the biological responses of SMFs exposure at an intensity of 10 T on the sperms and their offspring in him-5 male mutants of Caenorhabditis elegans (C. elegans). The size of unactivated sperms was deceased by 10 T SMF exposure, instead of the morphology. Exposure to 10 T SMF significantly altered the function of sperms in him-5 worms including the activation of sperms and the non-transferred ratio of sperms. In addition, the brood size assay revealed that 10 T SMF exposure eventually diminished the reproductive capacity of him-5 male worms. The lifespan of outcrossed offspring from exposed him-5 male mutants and unexposed fog-2 female mutants was decreased by 10 T SMF in a time dependent manner. Together, our findings provide novel information regarding the adverse effects of high SMFs on the sperms of C. elegans and their offspring, which can improve our understanding of the fundamental aspects of high SMFs on biological system.

Towards super-resolved terahertz microscopy for cellular imaging

Biomedical imaging includes the use of a variety of techniques to study organs and tissues. Some of the possible imaging modalities are more spread at clinical level (CT, MRI, PET), while others, such as light and electron microscopy are preferred in life sciences research. The choice of the imaging modalities can be based on the capability to study functional aspects of an organism, the delivered radiation dose to the patient, and the achievable resolution. In the last few decades, spectroscopists and imaging scientists have been interested in the use of terahertz (THz) frequencies (30 μm to 3 mm wavelength) due to the low photon energy associated (E∼1 meV, not causing breaking of the molecular bonds but still interacting with some vibrational modes) and the high penetration depth that is achievable. THz has been already adopted in security, quality control and material sciences. However, the adoption of THz frequencies for biological and clinical imaging means to face, as a major limitation, the very scarce resolution associated with the use of such long wavelengths. To address this aspect and reconcile the benefit of minimal harmfulness for bioimaging with the achievable resolving power, many attempts have been made. This review summarises the state-of-the-art of THz imaging applications aimed at achieving super-resolution, describing how practical aspects of optics and quasi-optics may be treated to efficaciously implement the use of THz as a new low-dose and versatile modality in biomedical imaging and clinical research.

MRI lung lobe segmentation in pediatric cystic fibrosis patients using a recurrent neural network trained with publicly accessible CT datasets

PURPOSE

To introduce a widely applicable workflow for pulmonary lobe segmentation of MR images using a recurrent neural network (RNN) trained with chest CT datasets. The feasibility is demonstrated for 2D coronal ultrafast balanced SSFP (ufSSFP) MRI.

METHODS

Lung lobes of 250 publicly accessible CT datasets of adults were segmented with an open-source CT-specific algorithm. To match 2D ufSSFP MRI data of pediatric patients, both CT data and segmentations were translated into pseudo-MR images that were masked to suppress anatomy outside the lung. Network-1 was trained with pseudo-MR images and lobe segmentations and then applied to 1000 masked ufSSFP images to predict lobe segmentations. These outputs were directly used as targets to train Network-2 and Network-3 with non-masked ufSSFP data as inputs, as well as an additional whole-lung mask as input for Network-2. Network predictions were compared to reference manual lobe segmentations of ufSSFP data in 20 pediatric cystic fibrosis patients. Manual lobe segmentations were performed by splitting available whole-lung segmentations into lobes.

RESULTS

Network-1 was able to segment the lobes of ufSSFP images, and Network-2 and Network-3 further increased segmentation accuracy and robustness. The average all-lobe Dice similarity coefficients were 95.0 ± 2.8 (mean ± pooled SD [%]) and 96.4 ± 2.5, 93.0 ± 2.0; and the average median Hausdorff distances were 6.1 ± 0.9 (mean ± SD [mm]), 5.3 ± 1.1, 7.1 ± 1.3 for Network-1, Network-2, and Network-3, respectively.

CONCLUSION

Recurrent neural network lung lobe segmentation of 2D ufSSFP imaging is feasible, in good agreement with manual segmentations. The proposed workflow might provide access to automated lobe segmentations for various lung MRI examinations and quantitative analyses.

Rates of MRI simulator utilisation in a tertiary cancer therapy centre

Magnetic resonance imaging (MRI) is increasingly being integrated into the radiation oncology workflow, due to its improved soft tissue contrast without additional exposure to ionising radiation. A review of MRI utilisation according to evidence based departmental guidelines was performed. Guideline utilisation rates were calculated to be 50% (true utilisation rate was 46%) of all new cancer patients treated with adjuvant or curative intent, excluding simple skin and breast cancer patients. Guideline utilisation rates were highest in the lower gastrointestinal and gynaecological subsites, with the lowest being in the upper gastrointestinal and thorax subsites. Head and neck (38% vs 45%) and CNS (46% vs 67%) cancers had the largest discrepancy between true and guideline utilisation rates due to unnamed reasons and non-contemporaneous diagnostic imaging respectively. This report outlines approximate MRI utilisation rates in a tertiary radiation oncology service and may help guide planning for future departments contemplating installation of an MRI simulator.

A Novel Brain Tumor Detection and Coloring Technique from 2D MRI Images

The early automated identification of brain tumors is a difficult task in MRI images. For a long time, continuous research efforts have floated a new idea of replacing different grayscale anatomic regions of diagnostic images with appropriate colors that could overcome the problems being faced by radiologists. The colorization of grayscale images is challenging for enhancing various regions’ contrasts by transforming grayscale images into high-contrast color images. This study investigates standard solutions in discriminating between normal and abnormal regions by assigning colors to grayscale human brain MR images to differentiate different kinds of tissues. The proposed approach is influenced by connected component and index-based colorization methods for applying colors to different regions and abnormal areas. It is an automated approach that varies its inputs using luminance and pixel matrix values and provides the possible outcome. After segmentation, a specific algorithm is devised to colorize the region-of-interest (ROI) areas, which distinguishes and applies colors to differentiate the regions. Results show that implementing the watershed-based area segmentation method and ROI selection method based on the morphological operation helps identify tissues during processing. Moreover, the colorization approach based on luminance and pixel matrix after segmentation and ROI selection is beneficial due to better PSNR and SSIM values and visible contrast improvement. Our proposed algorithm works with less processing overhead and uses less time than those of the industry’s previously used color transfer method.

AAPM Task Group Report 303 endorsed by the ABS: MRI Implementation in HDR Brachytherapy-Considerations from Simulation to Treatment

The Task Group (TG) on Magnetic Resonance Imaging (MRI) Implementation in High Dose Rate (HDR) Brachytherapy - Considerations from Simulation to Treatment, TG 303, was constituted by the American Association of Physicists in Medicine's (AAPM's) Science Council under the direction of the Therapy Physics Committee, the Brachytherapy Subcommittee, and the Working Group on Brachytherapy Clinical Applications. The TG was charged with developing recommendations for commissioning, clinical implementation, and on-going quality assurance (QA). Additionally, the TG was charged with describing HDR brachytherapy (BT) workflows and evaluating practical consideration that arise when implementing MR imaging. For brevity, the report is focused on the treatment of gynecologic and prostate cancer. The TG report provides an introduction and rationale for MRI implementation in BT, a review of previous publications on topics including available applicators, clinical trials, previously published BT related TG reports, and new image guided recommendations beyond CT based practices. The report describes MRI protocols and methodologies, including recommendations for the clinical implementation and logical considerations for MR imaging for HDR BT. Given the evolution from prescriptive to risk-based QA,¹ an example of a risk-based analysis using MRI-based, prostate HDR BT is presented. In summary, the TG report is intended to provide clear and comprehensive guidelines and recommendations for commissioning, clinical implementation, and QA for MRI-based HDR BT that may be utilized by the medical physics community to streamline this process. This report is endorsed by the American Brachytherapy Society (ABS). This article is protected by copyright. All rights reserved.

Defining an optimal surveillance strategy for patients following choledochal cyst resection: results of a systematic review

BACKGROUND

Choledochal cysts should be treated with complete surgical resection, or, rarely liver transplantation. Treated patients can remain at risk of developing metachronous cholangiocarcinomas and lifelong follow up is indicated. However, there is no agreement on what constitutes an acceptable follow up strategy. This review was undertaken to develop an evidenced based surveillance strategy.

METHODS

A systematic review of MEDLINE, EMBASE, PubMed, Web of Science, and Google Scholar was undertaken for reports (published up to 10 September 2021) describing late biliary complications and development of metachronous cholangiocarcinoma following choledochal cyst resection.

RESULTS

Twenty-five publications described 74 metachronous cholangiocarcinomas occurring in 3911 patients (overall incidence 2%). Cancers developed commonly at the hepatic hilus and were diagnosed after a median interval of 92 months (range 9-249 months) after the initial resection. While reporting is incomplete, the majority of cholangiocarcinomas developed following resection of type I and type IV cysts with few metachronous cancers recorded after treatment of type II or III cysts. Peak age range for presentation with metachronous cholangiocarcinoma is in the twenties following cyst resection in childhood suggesting that patients are at greatest risk for metachronous tumour development for up to 20 years (240 months).

CONCLUSION

A surveillance strategy is proposed for patients treated primarily for cyst types I and IV and unresected type V using annual liver function tests, Ca 19-9 measurement and biannual ultrasound assessment for 20 years post cyst resection, with biannual liver function testing, Ca 19-9 measurement and three yearly ultrasound assessment thereafter.

Magnetic resonance imaging for the diagnosis of hepatocellular carcinoma in adults with chronic liver disease

BACKGROUND

Hepatocellular carcinoma occurs mostly in people with chronic liver disease and ranks sixth in terms of global incidence of cancer, and third in terms of cancer deaths. In clinical practice, magnetic resonance imaging (MRI) is used as a second-line diagnostic imaging modality to confirm the presence of focal liver lesions suspected as hepatocellular carcinoma on prior diagnostic test such as abdominal ultrasound or alpha-fetoprotein, or both, either in surveillance programmes or in clinical settings. According to current guidelines, a single contrast-enhanced imaging study (computed tomography (CT) or MRI) showing typical hallmarks of hepatocellular carcinoma in people with cirrhosis is considered valid to diagnose hepatocellular carcinoma. The detection of hepatocellular carcinoma amenable to surgical resection could improve the prognosis. However, a significant number of hepatocellular carcinomas do not show typical hallmarks on imaging modalities, and hepatocellular carcinoma may, therefore, be missed. There is no clear evidence of the benefit of surveillance programmes in terms of overall survival: the conflicting results can be a consequence of inaccurate detection, ineffective treatment, or both. Assessing the diagnostic accuracy of MRI may clarify whether the absence of benefit could be related to underdiagnosis. Furthermore, an assessment of the accuracy of MRI in people with chronic liver disease who are not included in surveillance programmes is needed for either ruling out or diagnosing hepatocellular carcinoma.

OBJECTIVES

Primary: to assess the diagnostic accuracy of MRI for the diagnosis of hepatocellular carcinoma of any size and at any stage in adults with chronic liver disease. Secondary: to assess the diagnostic accuracy of MRI for the diagnosis of resectable hepatocellular carcinoma in adults with chronic liver disease, and to identify potential sources of heterogeneity in the results.

SEARCH METHODS

We searched the Cochrane Hepato-Biliary Group Controlled Trials Register, the Cochrane Hepato-Biliary Group Diagnostic Test of Accuracy Studies Register, the Cochrane Library, MEDLINE, Embase, and three other databases to 9 November 2021. We manually searched articles retrieved, contacted experts, handsearched abstract books from meetings held during the last 10 years, and searched for literature in OpenGrey (9 November 2021). Further information was requested by e-mails, but no additional information was provided. No data was obtained through correspondence with investigators. We applied no language or document-type restrictions.

SELECTION CRITERIA

Studies assessing the diagnostic accuracy of MRI for the diagnosis of hepatocellular carcinoma in adults with chronic liver disease, with cross-sectional designs, using one of the acceptable reference standards, such as pathology of the explanted liver and histology of resected or biopsied focal liver lesion with at least a six-month follow-up.

DATA COLLECTION AND ANALYSIS

At least two review authors independently screened studies, extracted data, and assessed the risk of bias and applicability concerns, using the QUADAS-2 checklist. We presented the results of sensitivity and specificity, using paired forest plots, and we tabulated the results. We used a hierarchical meta-analysis model where appropriate. We presented uncertainty of the accuracy estimates using 95% confidence intervals (CIs). We double-checked all data extractions and analyses.

MAIN RESULTS

We included 34 studies, with 4841 participants. We judged all studies to be at high risk of bias in at least one domain because most studies used different reference standards, often inappropriate to exclude the presence of the target condition, and the time interval between the index test and the reference standard was rarely defined. Regarding applicability, we judged 15% (5/34) of studies to be at low concern and 85% (29/34) of studies to be at high concern mostly owing to characteristics of the participants, most of whom were on waiting lists for orthotopic liver transplantation, and due to pathology of the explanted liver being the only reference standard. MRI for hepatocellular carcinoma of any size and stage: sensitivity 84.4% (95% CI 80.1% to 87.9%) and specificity 93.8% (95% CI 90.1% to 96.1%) (34 studies, 4841 participants; low-certainty evidence). MRI for resectable hepatocellular carcinoma: sensitivity 84.3% (95% CI 77.6% to 89.3%) and specificity 92.9% (95% CI 88.3% to 95.9%) (16 studies, 2150 participants; low-certainty evidence). The observed heterogeneity in the results remains mostly unexplained. The sensitivity analyses, which included only studies with clearly prespecified positivity criteria and only studies in which the reference standard results were interpreted without knowledge of the results of the index test, showed no variation in the results.

AUTHORS' CONCLUSIONS

We found that using MRI as a second-line imaging modality to diagnose hepatocellular carcinoma of any size and stage, 16% of people with hepatocellular carcinoma would be missed, and 6% of people without hepatocellular carcinoma would be unnecessarily treated. For resectable hepatocellular carcinoma, we found that 16% of people with resectable hepatocellular carcinoma would improperly not be resected, while 7% of people without hepatocellular carcinoma would undergo inappropriate surgery. The uncertainty resulting from the high risk of bias in the included studies and concerns regarding their applicability limit our ability to confidently draw conclusions based on our results.

MRI Safety Practice Observations in MRI Facilities Within the Kingdom of Jordan, Compared to the 2020 Manual on MR Safety of the American College of Radiology

Purpose

The absence of ionizing radiation in MRI applications does not guarantee absolute safety. Implementing of safety guidelines can ensure high-quality practice in the clinical MRI with the minimum risk. For this purpose, this cross-section quantitative study conducted in Jordan Kingdom aimed to assess current MRI safety guidelines in comparison with those of 2020 Manual on MR Safety of the American College of Radiology (ACR).

Patients and Methods

A site observation study of 38 MRI units was undertaken in June 2021. A well-structured MRI safety questionnaire was the primary data collection method. Data were subjected to a descriptive statistics content analysis by the SPSS version 20. The results were analyzed to yield comprehensive discussions.

Results

A total of 38 MRI facilities in participated in this study with the responding rate of 44.7%. Patient screening areas and changing rooms were available in about 29% (11/38) of the MRI facilities. Most facilities (55%, 21/38) conducted verbal screening only whereas 21% implemented both written and verbal screening for their patients and companions in zone II, which was present in a percentage of 29% in the approached facilities. Meanwhile, only 13 (43.2%) of 38 facilities used handheld magnets for physical screening, 25 (65.8%) of MRI units did not use any kind of ferromagnetic metal detection systems. Three (7.9%) participating centers had MR-safe wheelchairs, ventilators, anesthesia machines, and stretchers. Most MRI facilities participating in this study (71%) had emergency preparedness plans for alternative power outages. Despite a relatively low number of participating centers having an emergency exit or code (26.3% and 10.5%, respectively), none of them performed practice drills for such scenarios.

Conclusion

Investing in new MR-safe equipment requires introducing ferromagnetic detecting systems. More research is needed to establish the degree of MRI professional’s safety-related education.

Dimensions and forms of artefacts in 1.5 T and 3 T MRI caused by cochlear implants

Cochlear implantation is a standard treatment option due to expanding indications. Cranial magnetic resonance imaging (cMRI) has become a widespread diagnostic tool. Therefore, an increased number of cochlear implant (CI) users are undergoing cMRI scans. This study aimed to investigate the issue of the CI magnet impacting MRI quality and artifacts. 1.5 T and 3 T MRI scans with 4 defined sequences (T2-TSE, T2-TIRM, T1-3D-MPRAGE, and TDI) were performed on a phantom with a CI (SYNCHRONY System by MED-EL Austria) in place. The resulting MRI artifacts were retrospectively compared to MRI artifacts observed in patients with a CI. All images were transferred to AMIRA and visualized by manual segmentation. Usable image quality was achieved in three sequences (T2-TSE, T2-TIRM and T1-mprage). Observed artifacts differed in shape and size depending on the sequence. Maximum diameters of signal void areas ranged from 58 × 108 × 98 mm to 127 × 123 × 153 mm. Image distortions were larger. MRI artifacts caused by the SYNCHRONY system are asymmetric with varying shape, depending on the sequence. The phantom artefacts are similar to those in CI users. Considering the observed asymmetry, the hypothesis of varying implantation locations resulting in varying positions of the signal void area needs to be further investigated.

Clinical and Radiological Safety of Retained Implantable Doppler Devices Used for Free Flap Monitoring

INTRODUCTION

Implantable Doppler devices are reliable adjuncts used for free flap monitoring. Occasionally, the probe/wire is not removed and remains in the soft tissues. The clinical safety of the retained probes and safety and compatibility with magnetic resonance imaging (MRI) have not been studied. We present a series of retained implantable Doppler probes examining clinic outcomes, safety and compatibility with MRI, and effect on MRI image quality.

METHODS

A retrospective review was conducted of patients who had an implantable Doppler device for free flap monitoring between July 2007 and August 2018. Routine post-operative imaging was reviewed for all patients to identify incidental findings of a retained probe. A subset of patients with retained implantable Doppler probes who underwent MRI was identified. Magnetic resonance images were reviewed to detect any degradation of image quality.

RESULTS

A total of 323 patients who had an implantable Doppler device placed were reviewed 18 (5.6%) patients were identified with a retained probe and were included in this study. Mean age was 49 years with mean follow-up of 34.4 months. One potential device-related complication occurred in 1 (5.6%) patient. A total of 32 MRI scans were performed in 8 patients with retained devices, including 6 patients who underwent a total of 21 MRIs of the surgical site. There were no complications related to the MRI scans, and we found no significant degradation of image quality.

CONCLUSION

Retained implantable Doppler probes were not associated with substantial adverse clinical outcomes nor affected MRI image quality of the surgical site.

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.

Shape Prediction of Nasal Bones by Digital 2D-Photogrammetry of the Nose Based on Convolution and Back-Propagation Neural Network

In rhinoplasty, it is necessary to consider the correlation between the anthropometric indicators of the nasal bone, so that it prevents surgical complications and enhances the patient's satisfaction. The penetrating form of high-energy electromagnetic radiation is highly impacted on human health, which has often raised concerns of alternative method for facial analysis. The critical stage to assess nasal morphology is the nasal analysis on its anthropology that is highly reliant on the understanding of the structural features of the nasal radix. For example, the shape and size of nasal bone features, skin thickness, and also body factors aggregated from different facial anthropology values. In medical diagnosis, however, the morphology of the nasal bone is determined manually and significantly relies on the clinician's expertise. Furthermore, the evaluation anthropological keypoint of the nasal bone is nonrepeatable and laborious, also finding widely differ and intralaboratory variability in the results because of facial soft tissue and equipment defects. In order to overcome these problems, we propose specialized convolutional neural network (CNN) architecture to accurately predict nasal measurement based on digital 2D photogrammetry. To boost performance and efficacy, it is deliberately constructed with many layers and different filter sizes, with less filters and optimizing parameters. Through its result, the back-propagation neural network (BPNN) indicated the correlation between differences in human body factors mentioned are height, weight known as body mass index (BMI), age, gender, and the nasal bone dimension of the participant. With full of parameters could the nasal morphology be diagnostic continuously. The model's performance is evaluated on various newest architecture models such as DenseNet, ConvNet, Inception, VGG, and MobileNet. Experiments were directly conducted on different facials. The results show the proposed architecture worked well in terms of nasal properties achieved which utilize four statistical criteria named mean average precision (mAP), mean absolute error (MAE), R-square (R²), and T-test analyzed. Data has also shown that the nasal shape of Southeast Asians, especially Vietnamese, could be divided into different types in two perspective views. From cadavers for bony datasets, nasal bones can be classified into 2 morphological types in the lateral view which “V” shape was presented by 78.8% and the remains were “S” shape evaluated based on Lazovic (2015). With 2 angular dimension averages are 136.41 ± 7.99 and 104.25 ± 5.95 represented by the nasofrontal angle (g-n-prn) and the nasomental angle (n-prn-sn), respectively. For frontal view, classified by Hwang, Tae-Sun, et al. (2005), nasal morphology of Vietnamese participants could be divided into three types: type A was present in 57.6% and type B was present in 30.3% of the noses. In particular, types C, D, and E were not a common form of Vietnamese which includes the remaining number of participants. In conclusion, the proposed model performed the potential hybrid of CNN and BPNN with its application to give expected accuracy in terms of keypoint localization and nasal morphology regression. Nasal analysis can replace MRI imaging diagnostics that are reflected by the risk to human body.

Clinical Applications of Biological Dosimetry in Patients Exposed to Low Dose Radiation Due to Radiological, Imaging or Nuclear Medicine Procedures

Radiation dosimetric biomarkers have found applications beyond radiation protection area and now are actively introduced into clinical practice. Cytogenetic assays appeared to be a valuable tool for individualized quantifying radiation effects in patients, with high capability for assessing genotoxicity of various medical exposure modalities and providing meaningful radiation dose estimates for prognoses of radiation-related cancer risk. This review summarized current data on the use of biological dosimetry methods in patients undergoing various medical irradiations to low doses. The highlighted topics include basic aspects of biological dosimetry and its limitations in the range of low radiation doses, and main patterns of in vivo induction of radiation biomarkers in clinical exposure scenarios, occurring in X-ray diagnostics, computed tomography, interventional radiology, low dose radiotherapy, and nuclear medicine (internally administered ¹³¹I and other radiopharmaceuticals). Additionally, several specific issues, examined by biodosimetry techniques, are analysed, such as contrast media effect, radiation response in pediatric patients, impact of magnetic resonance imaging, evaluation of radioprotectors, detection of patients' abnormal intrinsic radiosensitivity and dose estimation in persons involved in medical radiation incidents. A prognosis of possible directions for further improvements in this area includes the automation of cytogenetic analysis, introduction of molecular biodosimeters and development of multiparametric biodosimetry platforms. A potential approach to the advanced biodosimetry of internal exposure and/or low dose external irradiation is suggested; this can be a multiparametric platform based on the combination of the γ-H2AX foci, dicentric, and translocation assays, each applied in the optimum postexposure time range, with the amalgamation of the dose estimates. The study revealed the necessity of further research, which might clarify medical radiation safety concerns for patients via using stringent biodosimetry methodology.

Radio Frequency MRI coils and safety: how infrared thermography can support quality assurance

Background

The safety controls in Resonance Magnetic Imaging (MRI) diagnostic site are numerous and complex. Some of these are contained in international directives and regularly conducted by medical physics expert after acceptance tests, consisting of a series of checks, measurements, evaluations called quality controls (QCs) and made to guarantee the image quality of the equipment. In this context, ensuring that the coils are in proper operating conditions is important to prevent and reduce errors in use and to preserve patient safety.

Results

A study by thermography was conducted to evaluate temperature changes of MRI coils during Quality Control (QC), in order to prevent any problems for the patient due to Radio Frequency waves. This experiment involves use of a thermal camera to detect temperature variations during MRI scans using head and body coils of two different tomography 1.5 T and 3.0 T static magnetic field. Thermal camera was positioned inside the MRI room to acquire images every 15 s for all the scansions duration. The observations have shown a temperature increase only for body coil of 1.5 MRI tomography, whereas no significative temperature variation has occurred for the other coils under observation. This temperature increase was later related to a fault of such coil.

Conclusions

The authors believe this simple method useful as first approach, during routinely QCs, to verify coils functioning and so to avoid patient hazards and are preparing a methodological study about functioning of the coils with respect to their temperature variation.

Magnetic resonance imaging versus cone beam computed tomography in diagnosis of periapical pathosis – A systematic review

Objective

The diagnosis of any dental pathology can vary from being simple to challenging. While the use of cone beam computed tomography (CBCT) is well established, magnetic resonance imaging (MRI) remains a proof of concept. This systematic review aims to compare the diagnostic ability of MRI with CBCT in diagnosing periapical pathosis.

Materials and Methods

This systematic search was performed using the electronic databases of MEDLINE, Cochrane Library, Google Scholar, and Science Direct to identify relevant articles from 2010 to 2020. The search terms used were magnetic resonance imaging, cone beam computed tomography, diagnosis, and periapical diseases.

Result

In total, 3218 potentially relevant abstracts and titles were identified. After removing duplicates, 1288 articles were reviewed for titles and abstracts, and 29 articles were selected for full-text reading. From those, 19 articles were finally selected that included original research studies, case reports, and case series and were included for systematic review. Most of the studies included in this review suggested that the combined use of CBCT and MRI is needed for a better and more precise diagnosis of complex periapical pathoses. The main advantage of MRI is its ability to image soft tissues usingnonionizing radiation, and the main disadvantage in the case of CBCT is overdiagnosis of the lesion.

Conclusion

MRI has various advantages over CBCT with similar diagnostic utility. When diagnosing periapical pathogens, both MRI and CBCT are needed for an accurate diagnosis.

Enhancing Magnetic Hyperthermia Nanoparticle Heating Efficiency with Non-Sinusoidal Alternating Magnetic Field Waveforms

For decades now, conventional sinusoidal signals have been exclusively used in magnetic hyperthermia as the only alternating magnetic field waveform to excite magnetic nanoparticles. However, there are no theoretical nor experimental reasons that prevent the use of different waveforms. The only justifiable motive behind using the sinusoidal signal is its availability and the facility to produce it. Following the development of a configurable alternating magnetic field generator, we aim to study the effect of various waveforms on the heat production effectiveness of magnetic nanoparticles, seeking to prove that signals with more significant slope values, such as the trapezoidal and almost-square signals, allow the nanoparticles to reach higher efficiency in heat generation. Furthermore, we seek to point out that the nanoparticle power dissipation is dependent on the waveform's slope and not only the frequency, magnetic field intensity and the nanoparticle size. The experimental results showed a remarkably higher heat production performance of the nanoparticles when exposed to trapezoidal and almost-square signals than conventional sinusoidal signals. We conclude that the nanoparticles respond better to the trapezoidal and almost-square signals. On the other hand, the experimental results were used to calculate the normalized power dissipation value and prove its dependency on the slope. However, adjustments are necessary to the coil before proceeding with in vitro and in vivo studies to handle the magnetic fields required.

Comparison of 3-D mandibular surfaces generated by MRI and CT

OBJECTIVE

The purpose of this study was to evaluate the errors of three-dimensional mandibular surfaces generated using magnetic resonance imaging (MRI) when computed tomography (CT) was set as the gold standard.

SETTINGS AND SAMPLE POPULATION

Seven patients with orthognathic deformities who had undergone CT and MRI scans were included in the study.

MATERIALS AND METHODS

Mandibular surfaces were generated on each CT and MR image by the surface-rendering method. Intra-individual reliability between CT and MRI was statistically tested by the confidence limits of agreement (LOA) for systematic error, 95% confidence interval minimal detectable change (MDC₉₅ ) for random error and intra-class correlation coefficient (ICC).

RESULTS

The average total error was 1.6 mm. The greatest MDC₉₅ was observed in the coronoid region in all directions. The other regions showed MDC₉₅ values of < 1.8 mm (transvers direction), 3.5 mm (vertical direction) and 1.7 mm (antero-posterior direction). ICCs showed 'almost perfect' agreement with respect to all regions.

CONCLUSION

Random errors were quantified for 3-D rendering of the mandible from MRI data. Although the coronoid region showed the greatest errors, the other regions of the mandibular surfaces generated using MRI were able to be evaluated.

Radiobiological effects and medical applications of non-ionizing radiation

Radiation is used in medicine to diagnose and treat diseases but it can also cause harm to the body by burning or mutation. This depends on whether the radiation is ionizing or nonionizing. Despite its vast applications in surgery, dermatology and cosmetics, little is taught and thus known about non-ionizing radiation. This review article discusses the fundamentals of non-ionizing electromagnetic radiations. The main aim is to extensively explain the different types of non-ionizing radiation. This will equip students and medical personnel with knowledge on different medical applications and expose them to a variety of specializations in medicine that utilize non-ionizing radiation. The article discusses the physics, hazard, means of protection and medical application of each type of radiation: ultraviolet radiation, light (both visible light and LASER), infrared radiation, microwaves and extremely low frequency radiation separately. It presents these terms in a simple manner that avoids rigors mathematics and physics, which makes them comprehensible for medical students. The development of new diagnostic and therapeutic approaches could also lead to increased hazards to the body unless they are treated with precaution. If not adequately monitored, a significant health risk may be posed to potentially exposed employees. Hence proper dosage should be used for non-ionizing radiation. This is only possible through understanding of the risks/benefits of these radiations by studying the physics and radiobiological effects of each individual radiation.

Occupational exposure to electromagnetic fields in magnetic resonance environment: an update on regulation, exposure assessment techniques, health risk evaluation, and surveillance

Magnetic resonance imaging (MRI) is one of the most-used diagnostic imaging methods worldwide. There are ∼50,000 MRI scanners worldwide each of which involves a minimum of five workers from different disciplines who spend their working days around MRI scanners. This review analyzes the state of the art of literature about the several aspects of the occupational exposure to electromagnetic fields (EMF) in MRI: regulations, literature studies on biological effects, and health surveillance are addressed here in detail, along with a summary of the main approaches for exposure assessment. The original research papers published from 2013 to 2021 in international peer-reviewed journals, in the English language, are analyzed, together with documents published by legislative bodies. The key points for each topic are identified and described together with useful tips for precise safeguarding of MRI operators, in terms of exposure assessment, studies on biological effects, and health surveillance.

Gadolinium-labeled affibody-XTEN recombinant vector for detection of HER2+ lesions of ovarian cancer lung metastasis using quantitative MRI

Ovarian cancer has the highest mortality rate among all gynecologic malignancies. HER2⁺ ovarian cancer is a subtype that is aggressive and associated with metastasis to distant sites such as the lungs. Therefore, accurate biological characterization of metastatic lesions is vital as it helps physicians select the most effective treatment strategy. Functional imaging of ovarian cancer with PET/CT is routinely used in the clinic to detect metastatic disease and evaluate treatment response. However, this imaging method does not provide information regarding the presence or absence of cancer-specific cell surface biomarkers such as HER2. As a result, this method does not help physicians decide whether to choose immunotherapy to treat metastasis. To differentiate the HER2⁺ from HER2¯ lesions in ovarian cancer lung metastasis, AbX₅₀C_4:Gd vector composed of a HER2 targeting affibody and XTEN peptide was genetically engineered. It was then labeled with gadolinium (Gd) via a stable linker. The vector was characterized physicochemically and biologically to determine its purity, molecular weight, hydrodynamic size and surface charge, stability in serum, endotoxin levels, relaxivity and ability to target the HER2 antigen. Then, SCID mice were implanted with SKOV-3 (HER2⁺) and OVASC-1 (HER2¯) tumors in the lungs and injected with the Gd-labeled HER2 targeted AbX₅₀C₄:Gd vector. The mice were imaged using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), followed by R1-mapping and quantitative analysis of the images. Our data demonstrate that the developed HER2-targeted vector can differentiate HER2⁺ lung metastasis from HER2¯ lesions using DCE-MRI. The developed vector could potentially be used in conjunction with other imaging modalities to prescreen patients and identify candidates for immunotherapy while triaging those who may not be considered responsive.

Acute thalamic damage as a prognostic biomarker for post-traumatic epileptogenesis

OBJECTIVE

To identify magnetic resonance imaging (MRI) biomarkers for post-traumatic epilepsy.

METHODS

The EPITARGET (Targets and biomarkers for antiepileptogenesis, epitarget.eu) animal cohort completing T₂ relaxation and diffusion tensor MRI follow-up and 1-month-long video-electroencephalography monitoring included 98 male Sprague-Dawley rats with traumatic brain injury and 18 controls. T₂ imaging was performed on day (D) 2, D7, and D21 and diffusion tensor imaging (DTI) on D7 and D21 using a 7-Tesla Bruker PharmaScan MRI scanner. The mean and standard deviation (SD) of the T₂ relaxation rate, multiple diffusivity measures, and diffusion anisotropy at each time-point within the ventroposterolateral and ventroposteromedial thalamus were used as predictor variables in multi-variable logistic regression models to distinguish rats with and without epilepsy.

RESULTS

Twenty-nine percent (28/98) of the rats with traumatic brain injury (TBI) developed epilepsy. The best-performing logistic regression model utilized the D2 and D7 T₂ relaxation time as well as the D7 diffusion tensor data. The model distinguished rats with and without epilepsy (Bonferroni-corrected p-value < .001) with a cross-validated concordance statistic of 0.74 (95% confidence interval [CI] 0.60-0.84). In a cross-validated classification test, the model exhibited 54% sensitivity and 91% specificity, enriching the epilepsy rate within the study population from the expected 29% to 71%. A model using the D2 T₂ data only resulted in a 73% enriched epilepsy rate (regression p-value .007, cross-validated concordance 0.70, 95% CI 0.56-0.80, sensitivity 29%, specificity 96%).

SIGNIFICANCE

An MRI parameter set reporting on acute and subacute neuropathologic changes common to experimental and human TBI presents a diagnostic biomarker for post-traumatic epileptogenesis. Significant enrichment of the study population was achieved even when using a single time-point measurement, producing an expected epilepsy rate of 73%.

Components of a magnetic resonance imaging system and their relationship to safety and image quality

Magnetic resonance imaging (MRI) is a powerful diagnostic tool that can be optimized to display a wide range of clinical conditions. An MRI system consists of four major components: a main magnet formed by superconducting coils, gradient coils, radiofrequency (RF) coils, and computer systems. Each component has safety considerations. Unless carefully controlled, the MRI machine's strong static magnetic field could turn a ferromagnetic object into a harmful projectile or cause vertigo and headache. Switching magnetic fields in the gradients evokes loud noises in the scanner, which can be mitigated by ear protection. Gradients also generate varying magnetic fields that can cause peripheral nerve stimulation and muscle twitching. Magnetic fields produced by RF coils deposit energy in the body and can cause tissue heating (with the potential to cause skin burns). In this review, we provide an overview of the components of a typical clinical MRI scanner and its associated safety issues. We also discuss how the relationship between the scanning parameters can be manipulated to improve image quality while ensuring a safe operational environment for the patients and staff. Understanding the strengths and limitations of these parameters can enable users to choose optimal techniques for image acquisition, apply them in clinical practice, and improve the diagnostic accuracy of an MRI examination.

Clinical safety of intracranial EEG electrodes in MRI at 1.5 T and 3 T: a single-center experience and literature review

PURPOSE

Intracranial electroencephalography (EEG) can be a critical part of presurgical evaluation for drug resistant epilepsy. With the increasing use of intracranial EEG, the safety of these electrodes in the magnetic resonance imaging (MRI) environment remains a concern, particularly at higher field strengths. However, no studies have reported the MRI safety experience of intracranial electrodes at 3 T. We report an MRI safety review of patients with intracranial electrodes at 1.5 and 3 T.

METHODS

One hundred and sixty-five consecutive admissions for intracranial EEG monitoring were reviewed. A total of 184 MRI scans were performed on 135 patients over 140 admissions. These included 118 structural MRI studies at 1.5 T and 66 functional MRI studies at 3 T. The magnetic resonance (MR) protocols avoided the use of high specific energy absorption rate sequences that could result in electrode heating. The intracranial implantations included 114 depth, 15 subdural, and 11 combined subdural and depth electrodes. Medical records were reviewed for patient-reported complications and radiologic complications related to these studies. Pre-implantation, post-implantation, and post-explantation imaging studies were reviewed for potential complications.

RESULTS

No adverse events or complications were seen during or after MRI scanning at 1.5 or 3 T apart from those attributed to electrode implantation. There was also no clinical or imaging evidence of worsening of pre-existing implantation-related complications after MR imaging.

CONCLUSION

No clinical or radiographic complications are seen when performing MRI scans at 1.5 or 3 T on patients with implanted intracranial EEG electrodes while avoiding high specific energy absorption rate sequences.

Diagnostic and Therapeutic Nanomedicine

Nanotechnology has been widely applied to medical interventions for prevention, diagnostics, and therapeutics of diseases, and the application of nanotechnology for medical purposes, which is called as a term "nanomedicine" has received tremendous attention. In particular, the design and development of nanoparticle for biosensors have received a great deal of attention, since those are most impactful area of clinical translation showing potential breakthrough in early diagnosis of diseases such as cancers and infections. For example, the nanoparticles that have intrinsic unique features such as magnetic responsive characteristics or photoluminescence can be utilized for noninvasive visualization of inner body. Drug delivery that makes use of drug-containing nanoparticles as a carrier is another field of study, in which the particulate form nanomedicine is given by parenteral administration for further systemic targeting to pathological tissues. In addition, encapsulation into nanoparticles gives the opportunity to secure the sensitive therapeutic payloads that are readily degraded or deactivated until reached to the target in biological environments, or to provide sufficient solubilization (e.g., to deliver compounds which have physicochemical properties that strongly limit their aqueous solubility and therefore systemic bioavailability). The nanomedicine is further intended to enhance the targeting index such as increased specificity and reduced false binding, thus improve the diagnostic and therapeutic performances. In this chapter, principles of nanomaterials for medicine will be thoroughly covered with applications for imaging-based diagnostics and therapeutics.

The accuracy of different modalities of perforator mapping for unilateral DIEP flap breast reconstruction: A systematic review and meta-analysis

BACKGROUND

Perforator mapping may be performed prior to deep inferior epigastric perforator (DIEP) flap breast reconstruction to guide perforator selection. However, the accuracy of different imaging modalities remains unknown. This review aimed to evaluate the accuracy of different modalities for locating perforators for unipedicled DIEP flap breast reconstruction.

METHODS

MEDLINE and EMBASE were searched from inception to 24th September 2019 for studies concerning adult women undergoing DIEP flap breast reconstruction with preoperative perforator mapping. The index test was pre-operative imaging and the reference standard was intraoperative identification.

RESULTS

21 articles with 1146 women were included. Six methods were described; handheld doppler, colour doppler (duplex) ultrasonography, computed tomography angiography, magnetic resonance angiography (MRA), direct infrared thermography with and without doppler. Meta-analysis revealed 94% (95% CI 88-99%) of DIEPs identified as the 'dominant perforator' on imaging were chosen as dominant perforators intraoperatively. Colour doppler (Duplex) ultrasonography had the lowest agreement (mean 74% [95% CI 67-81%]) whilst MRA had the highest agreement (mean 97% [95% CI 86-100%]). There was no statistically significant difference in the performance of different tests. All studies were subject to bias as the operators had knowledge of the index test prior to conducting the reference standard.

CONCLUSIONS

Based upon limited evidence, cross sectional (CT/MR) imaging modalities for preoperative DIEP mapping appear to have similar accuracy and perform better than ultrasound.

Fetal Exposure to MR Imaging: Long-Term Neurodevelopmental Outcome

BACKGROUND AND PURPOSE

Very few studies have investigated long-term neurodevelopment of children exposed to MR imaging antenatally. Thus, the purpose of our study was to evaluate long-term neurodevelopmental outcomes of children exposed to MR imaging during pregnancy.

MATERIALS AND METHODS

We conducted a historical prospective cohort study in a single tertiary medical center. Women exposed to 1.5T noncontrast MR imaging for maternal or fetal indications were matched to unexposed controls. Long-term neurodevelopmental outcomes were evaluated of their children, 2.5 to 6 years of age, according to the Vineland-II Adaptive Behavior Scale. The Vineland-II Adaptive Behavior Scale assesses communication, daily living skills, socialization, and motor skills. A composite score summarizes these 4 domains.

RESULTS

A total of 131 exposed women matched our inclusion criteria and were included in the study group, and 771 unexposed women, in the control group. No difference was identified in the Vineland-II Adaptive Behavior Scale composite score between the children of the study and control groups (mean, 110.79 versus 108.18; P = .098). Differences were also not observed between the children of the 2 groups in 3 of the 4 questionnaire domains: communication (108.84 versus 109.10; P = .888), daily living skills (109.51 versus 108.28; P = .437), and motor skills (105.09 versus 104.42; P = .642). However, the socialization score was favorable for the study group (112.98 versus 106.47; P < .001).

CONCLUSIONS

Exposure to 1.5T noncontrast MR imaging during pregnancy had no harmful effects on long-term neurodevelopmental outcomes. This study contributes to understanding the safety of MR imaging during pregnancy.

KIM-1 and Kidney Disease Progression in Autosomal Dominant Polycystic Kidney Disease: HALT-PKD Results

BACKGROUND

Cyst compression of renal tubules plays a role in the progression of autosomal dominant polycystic kidney disease (ADPKD) and may induce expression of kidney injury molecule-1 (KIM-1). Whether urinary KIM-1 indexed for creatinine (uKIM-1/Cr) is a prognostic marker of disease progression in ADPKD is unknown.In this secondary analysis of a prospective cohort study, we sought to determine whether patients with high as opposed to low uKIM-1/CR at baseline had greater rates of eGFR loss and height-adjusted total kidney volume (HtTKV) increase.

METHODS

Baseline uKIM-1/Cr values were obtained from 754 participants in Halt Progression of Polycystic Kidney Disease (HALT-PKD) studies A (early ADPKD) and B (late ADPKD). The predictor was uKIM-1/Cr, which was dichotomized by a median value of 0.2417 pg/g, and the primary outcomes were measured longitudinally over time. Mixed-effects linear models were used in the analysis to calculate the annual slope of change in eGFR and HtTKV.

RESULTS

Patients with high uKIM-1/Cr (above the median) had an annual decline in eGFR that was 0.47 mL/min greater than that in those with low uKIM-1/Cr (p = 0.0015) after adjustment for all considered covariates. This association was seen in study B patients alone (0.45 mL/min; p = 0.009), but not in study A patients alone (0.42 mL/min; p = 0.06). High baseline uKIM-1/Cr was associated with higher HtTKV in the baseline cross-sectional analysis compared to low uKIM-1/Cr (p = 0.02), but there was no difference between the groups in the mixed-effects model annual slopes.

CONCLUSION

Elevated baseline uKIM-1/Cr is associated with a greater decline in eGFR over time. Further research is needed to determine whether uKIM-1/Cr improves risk stratification in patients with ADPKD.

Noninvasive high-resolution electromyometrial imaging of uterine contractions in a translational sheep model

In current clinical practice, uterine contractions are monitored via a tocodynamometer or an intrauterine pressure catheter, both of which provide crude information about contractions. Although electrohysterography/electromyography can measure uterine electrical activity, this method lacks spatial specificity and thus cannot accurately measure the exact location of electrical initiation and location-specific propagation patterns of uterine contractions. To comprehensively evaluate three-dimensional uterine electrical activation patterns, we describe here the development of electromyometrial imaging (EMMI) to display the three-dimensional uterine contractions at high spatial and temporal resolution. EMMI combines detailed body surface electrical recording with body-uterus geometry derived from magnetic resonance images. We used a sheep model to show that EMMI can reconstruct uterine electrical activation patterns from electrodes placed on the abdomen. These patterns closely match those measured with electrodes placed directly on the uterine surface. In addition, modeling experiments showed that EMMI reconstructions are minimally affected by noise and geometrical deformation. Last, we show that EMMI can be used to noninvasively measure uterine contractions in sheep in the same setup as would be used in humans. Our results indicate that EMMI can noninvasively, safely, accurately, robustly, and feasibly image three-dimensional uterine electrical activation during contractions in sheep and suggest that similar results might be obtained in clinical setting.