Strain-invariant stretchable radio-frequency electronics.

Wireless modules that provide telecommunications and power-harvesting capabilities enabled by radio-frequency (RF) electronics are vital components of skin-interfaced stretchable electronics1-7. However, recent studies on stretchable RF components have demonstrated that substantial changes in electrical properties, such as a shift in the antenna resonance frequency, occur even under relatively low elastic strains8-15. Such changes lead directly to greatly reduced wireless signal strength or power-transfer efficiency in stretchable systems, particularly in physically dynamic environments such as the surface of the skin. Here we present strain-invariant stretchable RF electronics capable of completely maintaining the original RF properties under various elastic strains using a 'dielectro-elastic' material as the substrate. Dielectro-elastic materials have physically tunable dielectric properties that effectively avert frequency shifts arising in interfacing RF electronics. Compared with conventional stretchable substrate materials, our material has superior electrical, mechanical and thermal properties that are suitable for high-performance stretchable RF electronics. In this paper, we describe the materials, fabrication and design strategies that serve as the foundation for enabling the strain-invariant behaviour of key RF components based on experimental and computational studies. Finally, we present a set of skin-interfaced wireless healthcare monitors based on strain-invariant stretchable RF electronics with a wireless operational distance of up to 30 m under strain.

Radiation damping at clinical field strength: Characterization and compensation in quantitative measurements.

PURPOSE: In any MR experiment, the bulk magnetization acts on itself, caused by the induced current in the RF receiver circuit that generates an oscillating damping field. This effect, known as "radiation damping" (RD), is usually weak and, therefore, unconsidered in MRI, but can affect quantitative studies performed with dedicated coils that provide a high SNR. The current work examined RD in a setup for investigations of small tissue specimens including a quantitative characterization of the spin-coil system. THEORY AND METHODS: A custom-made Helmholtz coil (radius and spacing 16 mm) was interfaced to a transmit-receive (Tx/Rx) switch with integrated passive feedback for modulation or suppression of RD similar to preamplifier decoupling. Pulse sequences included pulse-width arrays to demonstrate the absence/ presence of RD and difference techniques employing gradient pulses or composite RF pulses to quantify RD effects during free precession and transmission, respectively. Experiments were performed at 3T in small samples of MnCl2 solution. RESULTS: Significant RD effects may impact RF pulse application and evolution periods. Effective damping time constants were comparable to typical T2 * times or echo spacings in multi-echo sequences. Measurements of the phase relation showed that deviations from the commonly assumed 90° angle between the damping field and the transverse magnetization may occur. CONCLUSION: Radiation damping may affect the accuracy of quantitative MR measurements performed with dedicated RF coils. Efficient mitigation can be achieved hardware-based or by appropriate consideration in the pulse sequence.

The restricted SAR protocol: A method to assess MRI coil prototypes in an unconditionally safe manner.

PURPOSE: Testing an RF coil prototype on subjects involves laborious verifications to ensure its safety. In particular, it requires preliminary electromagnetic simulations and their validations on phantoms to accurately predict the specific absorption rate (SAR). For coil design validation with a simpler safety procedure, the restricted SAR (rS) mode is proposed, enabling representative first experiments in vivo. The goal of the developed approach is to accelerate the transition of a custom coil system from prototype to clinical use. METHODS: The restricted specific absorption rate (SAR) (rS) mode imposes a radical limitation on the transmitted RF power based on a worst-case scenario of local RF power absorption. The limitations used are independent of the SAR spatial distribution, making this approach unconditionally safe. The developed rS protocol contains the sequences required for coil evaluation and satisfies the imposed rS conditions. It provides a quantitative characterization of the coil transmission and reception profiles and a qualitative evaluation of the anatomical images. Protocol validation was performed on commercial and pre-industrial prototype coils on a small cohort of healthy volunteers. RESULTS: The proposed rS protocol enables coil evaluation within an acquisition time compatible with common clinical protocol duration. The total time of all evaluation steps does not exceed 17 min. At the same time, the global SAR remains 100 times less than the International Electrotechnical Commission safety limit for played sequences. CONCLUSION: The rS protocol allows characterizing and comparing coil prototypes on volunteers without extensive electromagnetic calculations and phantom validations in an unconditionally safe way.

Stealth RF energy harvesting in MRI using selective shielding.

PURPOSE: To utilize the transmit radiofrequency (RF) field in MRI as a power source, near or within the field of view but without affecting image quality or safety. METHODS: Power harvesting is performed by RF induction in a resonant coil. Resulting RF field distortion in the subject is canceled by a selective shield that couples to the harvester while being transparent to the RF transmitter. Such shielding is designed with the help of electromagnetic simulation. A shielded harvester of 3 cm diameter is implemented, assessed on the bench, and tested in a 3T MRI system, recording power yield during typical scans. RESULTS: The concept of selective shielding is confirmed by simulation. Bench tests show effective power harvesting in the presence of the shield. In the MRI system, it is confirmed that selective shielding virtually eliminates RF perturbation. In scans with the harvester immediately adjacent to a phantom, up to 100 mW of average power are harvested without affecting image quality. CONCLUSION: Selective shielding enables stealthy RF harvesting which can be used to supply wireless power to on-body devices during MRI.

Intra-scan RF power amplifier drift correction.

PURPOSE: The drift in radiofrequency (RF) power amplifiers (RFPAs) is assessed and several contributing factors are investigated. Two approaches for prospective correction of drift are proposed and their effectiveness is evaluated. METHODS: RFPA drift assessment encompasses both intra-pulse and inter-pulse drift analyses. Scan protocols with varying flip angle (FA), RF length, and pulse repetition time (TR) are used to gauge the influence of these parameters on drift. Directional couplers (DICOs) monitor the forward waveforms of the RFPA outputs. DICOs data is stored for evaluation, allowing calculation of correction factors to adjust RFPAs' transmit voltage. Two correction methods, predictive and run-time, are employed: predictive correction necessitates a calibration scan, while run-time correction calculates factors during the ongoing scan. RESULTS: RFPA drift is indeed influenced by the RF duty-cycle, and in the cases examined with a maximum duty-cycle of 66%, the potential drift is approximately 41% or 15%, depending on the specific RFPA revision. Notably, in low transmit voltage scenarios, FA has minimal impact on RFPA drift. The application of predictive and run-time drift correction techniques effectively reduces the average drift from 10.0% to less than 1%, resulting in enhanced MR signal stability. CONCLUSION: Utilizing DICO recordings and implementing a feedback mechanism enable the prospective correction of RFPA drift. Having a calibration scan, predictive correction can be utilized with fewer complexity; for enhanced performance, a run-time approach can be employed.

Improved 1 H body imaging at 10.5 T: Validation and VOP-enabled imaging in vivo with a 16-channel transceiver dipole array.

PURPOSE: To increase the RF coil performance and RF management for body imaging at 10.5 T by validating and evaluating a high-density 16-channel transceiver array, implementing virtual observation points (VOPs), and demonstrating specific absorption rate (SAR) constrained imaging in vivo. METHODS: The inaccuracy of the electromagnetic model of the array was quantified based on B1 + and SAR data. Inter-subject variability was estimated using a new approach based on the relative SAR deviation of different RF shims between human body models. The pTx performance of the 16-channel array was assessed in simulation by comparison to a previously demonstrated 10-channel array. In vivo imaging of the prostate was performed demonstrating SAR-constrained static RF shimming and acquisition modes optimized for refocused echoes (AMORE). RESULTS: The model inaccuracy of 29% and the inter-subject variability of 85% resulted in a total safety factor of 1.91 for pelvis studies. For renal and cardiac imaging, inter-subject variabilities of 121% and 141% lead to total safety factors of 2.25 and 2.45, respectively. The shorter wavelength at 10.5 T supported the increased element density of the 16-channel array which in turn outperformed the 10-channel version for all investigated metrics. Peak 10 g local SAR reduction of more than 25% without a loss of image quality was achieved in vivo, allowing a theoretical improvement in measurement efficiency of up to 66%. CONCLUSIONS: By validating and characterizing a 16-channel dipole transceiver array, this work demonstrates, for the first time, a VOP-enabled RF coil for human torso imaging enabling increased pTx performance at 10.5 T.

Local SAR management strategies to use two-channel RF shimming for fetal MRI at 3 T.

PURPOSE: This study evaluates the imaging performance of two-channel RF-shimming for fetal MRI at 3 T using four different local specific absorption rate (SAR) management strategies. METHODS: Due to the ambiguity of safe local SAR levels for fetal MRI, local SAR limits for RF shimming were determined based on either each individual's own SAR levels in standard imaging mode (CP mode) or the maximum SAR level observed across seven pregnant body models in CP mode. Local SAR was constrained either indirectly by further constraining the whole-body SAR (wbSAR) or directly by using subject-specific local SAR models. Each strategy was evaluated by the improvement of the transmit field efficiency (average |B1 + |) and nonuniformity (|B1 + | variation) inside the fetus compared with CP mode for the same wbSAR. RESULTS: Constraining wbSAR when using RF shimming decreases B1 + efficiency inside the fetus compared with CP mode (by 12%-30% on average), making it inefficient for SAR management. Using subject-specific models with SAR limits based on each individual's own CP mode SAR value, B1 + efficiency and nonuniformity are improved on average by 6% and 13% across seven pregnant models. In contrast, using SAR limits based on maximum CP mode SAR values across seven models, B1 + efficiency and nonuniformity are improved by 13% and 25%, compared with the best achievable improvement without SAR constraints: 15% and 26%. CONCLUSION: Two-channel RF-shimming can safely and significantly improve the transmit field inside the fetus when subject-specific models are used with local SAR limits based on maximum CP mode SAR levels in the pregnant population.

Investigation of alternative RF power limit control methods for 0.5T, 1.5T, and 3T parallel transmission cardiac imaging: A simulation study.

PURPOSE: To investigate safety and performance aspects of parallel-transmit (pTx) RF control-modes for a body coil at B 0 ≤ 3 T $$ {B}_0\le 3\mathrm{T} $$ . METHODS: Electromagnetic simulations of 11 human voxel models in cardiac imaging position were conducted for B 0 = 0.5 T $$ {B}_0=0.5\mathrm{T} $$ , 1.5 T $$ 1.5\mathrm{T} $$ and 3 T $$ 3\mathrm{T} $$ and a body coil with a configurable number of transmit channels (1, 2, 4, 8, 16). Three safety modes were considered: the 'SAR-controlled mode' (SCM), where specific absorption rate (SAR) is limited directly, a 'phase agnostic SAR-controlled mode' (PASCM), where phase information is neglected, and a 'power-controlled mode' (PCM), where the voltage amplitude for each channel is limited. For either mode, safety limits were established based on a set of 'anchor' simulations and then evaluated in 'target' simulations on previously unseen models. The comparison allowed to derive safety factors accounting for varying patient anatomies. All control modes were compared in terms of the B 1 + $$ {B}_1^{+} $$ amplitude and homogeneity they permit under their respective safety requirements. RESULTS: Large safety factors (approximately five) are needed if only one or two anchor models are investigated but they shrink with increasing number of anchors. The achievable B 1 + $$ {B}_1^{+} $$ is highest for SCM but this advantage is reduced when the safety factor is included. PCM appears to be more robust against variations of subjects. PASCM performance is mostly in between SCM and PCM. Compared to standard circularly polarized (CP) excitation, pTx offers minor B 1 + $$ {B}_1^{+} $$ improvements if local SAR limits are always enforced. CONCLUSION: PTx body coils can safely be used at B 0 ≤ 3 T $$ {B}_0\le 3\mathrm{T} $$ . Uncertainties in patient anatomy must be accounted for, however, by simulating many models.

Beat Pilot Tone (BPT): Simultaneous MRI and RF motion sensing at arbitrary frequencies.

PURPOSE: To introduce a simple system exploitation with the potential to turn MRI scanners into general-purpose radiofrequency (RF) motion monitoring systems. METHODS: Inspired by Pilot Tone (PT), this work proposes Beat Pilot Tone (BPT), in which two or more RF tones at arbitrary frequencies are transmitted continuously during the scan. These tones create motion-modulated standing wave patterns that are sensed by the receiver coil array, incidentally mixed by intermodulation in the receiver chain, and digitized simultaneously with the MRI data. BPT can operate at almost any frequency as long as the intermodulation products lie within the bandwidth of the receivers. BPT's mechanism is explained in electromagnetic simulations and validated experimentally. RESULTS: Phantom and volunteer experiments over a range of transmit frequencies suggest that BPT may offer frequency-dependent sensitivity to motion. Using a semi-flexible anterior receiver array, BPT appears to sense cardiac-induced body vibrations at microwave frequencies ( ≥ $$ \ge $$ 1.2 GHz). At lower frequencies, it exhibits a similar cardiac signal shape to PT, likely due to blood volume changes. Other volunteer experiments with respiratory, bulk, and head motion show that BPT can achieve greater sensitivity to motion than PT and greater separability between motion types. Basic multiple-input multiple-output ( 4 × 22 $$ 4\times 22 $$ MIMO) operation with simultaneous PT and BPT in head motion is demonstrated using two transmit antennas and a 22-channel head-neck coil. CONCLUSION: BPT may offer a rich source of motion information that is frequency-dependent, simultaneous, and complementary to PT and the MRI exam.

Robust EMI elimination for RF shielding-free MRI through deep learning direct MR signal prediction.

PURPOSE: To develop a new electromagnetic interference (EMI) elimination strategy for RF shielding-free MRI via active EMI sensing and deep learning direct MR signal prediction (Deep-DSP). METHODS: Deep-DSP is proposed to directly predict EMI-free MR signals. During scanning, MRI receive coil and EMI sensing coils simultaneously sample data within two windows (i.e., for MR data and EMI characterization data acquisition, respectively). Afterward, a residual U-Net model is trained using synthetic MRI receive coil data and EMI sensing coil data acquired during EMI signal characterization window, to predict EMI-free MR signals from signals acquired by MRI receive and EMI sensing coils. The trained model is then used to directly predict EMI-free MR signals from data acquired by MRI receive and sensing coils during the MR signal-acquisition window. This strategy was evaluated on an ultralow-field 0.055T brain MRI scanner without any RF shielding and a 1.5T whole-body scanner with incomplete RF shielding. RESULTS: Deep-DSP accurately predicted EMI-free MR signals in presence of strong EMI. It outperformed recently developed EDITER and convolutional neural network methods, yielding better EMI elimination and enabling use of few EMI sensing coils. Furthermore, it could work well without dedicated EMI characterization data. CONCLUSION: Deep-DSP presents an effective EMI elimination strategy that outperforms existing methods, advancing toward truly portable and patient-friendly MRI. It exploits electromagnetic coupling between MRI receive and EMI sensing coils as well as typical MR signal characteristics. Despite its deep learning nature, Deep-DSP framework is computationally simple and efficient.

Head-and-neck multichannel B1+ mapping and RF shimming of the carotid arteries using a 7T parallel-transmit head coil.

PURPOSE: Neurovascular MRI suffers from a rapid drop in B1 + into the neck when using transmit head coils at 7 T. One solution to improving B1 + magnitude in the major feeding arteries in the neck is to use custom RF shims on parallel-transmit head coils. However, calculating such shims requires robust multichannel B1 + maps in both the head and the neck, which is challenging due to low RF penetration into the neck, limited dynamic range of multichannel B1 + mapping techniques, and B0 sensitivity. We therefore sought a robust, large-dynamic-range, parallel-transmit field mapping protocol and tested whether RF shimming can improve carotid artery B1 + magnitude in practice. METHODS: A pipeline is presented that combines B1 + mapping data acquired using circularly polarized (CP) and CP2-mode RF shims at multiple voltages. The pipeline was evaluated by comparing the predicted and measured B1 + for multiple random transmit shims, and by assessing the ability of RF shimming to increase B1 + in the carotid arteries. RESULTS: The proposed method achieved good agreement between predicted and measured B1 + in both the head and the neck. The B1 + magnitude in the carotid arteries can be increased by 43% using tailored RF shims or by 37% using universal RF shims, while also improving the RF homogeneity compared with CP mode. CONCLUSION: B1 + in the neck can be increased using RF shims calculated from multichannel B1 + maps in both the head and the neck. This can be achieved using universal phase-only RF shims, facilitating easy implementation in existing sequences.

Flexible multi-purpose integrated RF/shim coil array for MRI and localized B0 shimming.

PURPOSE: To develop a flexible, lightweight, and multi-purpose integrated parallel reception, excitation, and shimming (iPRES) coil array that can conform to the subject's anatomy and perform MR imaging and localized B0 shimming in different anatomical regions with a high SNR, shimming performance, ease of positioning, and subject comfort. METHODS: A four-channel flexible iPRES coil array was constructed by enabling RF and direct currents to flow on the same flexible coil elements for imaging and shimming, respectively. Shimming experiments were performed with the coil array wrapped around the knee or neck of healthy subjects to demonstrate its high shimming performance and versatility. Additionally, its SNR and shimming performance in the knee were compared to those obtained with the coil array wrapped around a larger rigid tube designed to fit most knee sizes. RESULTS: Shimming with the coil array wrapped around the knee or neck resulted in an average reduction in B0 RMSE of 50.1% and 40.5% relative to first-order and second-order spherical harmonic shimming, respectively, and substantially reduced distortions in DWI images. In contrast, shimming the knee with the coil array wrapped around the rigid tube only provided a 29.6% reduction in B0 RMSE, whereas the SNR was reduced by 58.7%. CONCLUSION: The flexible iPRES coil array can conform to different anatomical regions and perform imaging and localized B0 shimming with a higher SNR, shimming performance, ease of positioning, and comfort compared to a rigid iPRES coil array, which should be valuable for many applications throughout the human body.

Detunable wireless Litzcage coil for human head MRI at 1.5 T.

Inductively coupled radiofrequency (RF) coils are an inexpensive and simple method to realize wireless RF coils in magnetic resonance imaging (MRI), which can significantly ease the MRI scan setup and improve patient comfort because they do not require bulky components such as cables, baluns, preamplifiers, and connectors. However, volume-type wireless coils are typically operated in transmit/receive mode because detuning such coils is much more challenging due to their complex structure and multiple resonant modes. Meanwhile, adding too many detuning circuits to a wireless coil would decrease the coil's quality factor, impair the signal-to-noise ratio, and increase the cost. In this work, we proposed, constructed, and tested a novel wireless volume coil based on the Litzcage design for 1.5-T head imaging. Being an inductively coupled coil, it has a much simpler structure, resulting in a lighter weight and less bulky design. Despite its simpler structure, it exhibits comparable imaging performance with a commercial receive array, providing an alternative to conventional wired coils with a high cost and complex structure. The unique figure-of-8 conductor pattern within the rungs ensures that the proposed wireless Litzcage can be efficiently detuned with minimal detuning circuits.

Optimization of flip angle and radiofrequency pulse phase to maximize steady-state magnetization in three-dimensional missing pulse steady-state free precession.

Missing pulse (MP) steady-state free precession (SSFP) is a magnetic resonance imaging (MRI) pulse sequence that is highly tolerant to the magnetic field inhomogeneity. In this study, optimal flip angle and radiofrequency (RF) phase scheduling in three-dimensional (3D) MP-SSFP is introduced to maximize the steady-state magnetization while keeping broadband excitation to cover widely distributed frequencies generated by inhomogeneous magnetic fields. Numerical optimization based on extended phase graph (EPG) simulation was performed to maximize the MP-SSFP steady-state magnetization. To limit the specific absorption rate (SAR) associated with the broadband excitation in 3D MP-SSFP, SAR constraint was introduced in the numerical optimization. Optimized flip angle and RF phase settings were experimentally tested by introducing a linear inhomogeneous magnetic field in a range of 10-20 mT/m and using a phantom with known T1/T2 relaxation and diffusion parameters at 3 T. The experimental results were validated through comparisons with EPG simulation. Image contrasts and molecular diffusion effects were investigated in in vivo human brain imaging with 3D MP-SSFP with the optimal flip angle and RF phase settings. In the phantom measurements, the optimal flip angle and RF phase settings improved the MP-SSFP steady-state magnetization/signal-to-noise ratio by up to 41% under the fixed SAR conditions, which matched well with EPG simulation results. In vivo brain imaging with the optimal RF pulse settings provided T2-like image contrasts. Diffusion effects were relatively minor with the linear inhomogeneous field of 10-20 mT/m for white and gray matter, but cerebrospinal fluid showed conspicuous signal intensity attenuation as the linear inhomogeneous field increased. Numerical optimization achieved significant improvement in the steady-state magnetization in MP-SSFP compared with the RF pulse settings used in previous studies. The proposed flip angle and RF phase optimization is promising to improve 3D MP-SSFP image quality for MRI in inhomogeneous magnetic fields.

A review of recent developments and applications of high-permittivity dielectric shimming in magnetic resonance.

We present a review outlining the basic mechanism, background, recent technical developments, and clinical applications of aqueous dielectric padding in the field of MRI. Originally meant to be a temporary solution, it has gained traction as an effective method for correcting B1 + inhomogeneities due to the unique properties of the calcium titanate and barium titanate perovskites used. Aqueous dielectric pads have used a variety of high-permittivity materials over the years to improve the quality of MRI acquisitions at 1.5 and 3 T and more recently for 7 T neuroimaging applications. The technical development and assessment of these pads have been advanced by an increased use of mathematical modeling and electromagnetic simulations. These tools have allowed for a more complete understanding of the physical interactions between dielectric pads and the RF coil, making testing and safety assessments more accurate. The ease of use and effectiveness that dielectric pads offer have allowed them to become more commonplace in tackling imaging challenges in more clinically focused environments. More recently, they have seen usage not only in anatomical imaging methods but also in specialized metabolic imaging sequences such as GluCEST and NOEMTR . New colossally high-permittivity materials have been proposed; however, practical utilization has been a continued challenge due to unfavorable frequency dependences as well as safety limitations. A new class of metasurfaces has been under development to address the shortcomings of conventional dielectric padding while also providing increased performance in enhancing MRI images.

The impact of variations in subject geometry, respiration and coil repositioning on the specific absorption rate in parallel transmit abdominal imaging at 7 T.

Parallel transmit MRI at 7 T has increasingly been adopted in research projects and provides increased signal-to-noise ratios and novel contrasts. However, the interactions of fields in the body need to be carefully considered to ensure safe scanning. Recent advances in physically flexible body coils have allowed for high-field abdominal imaging, but the effects of increased variability on energy deposition need further exploration. The aim of this study was to assess the impact of subject geometry, respiration phase and coil positioning on the specific absorption rate (SAR). Ten healthy subjects (body mass index [BMI] = 25 ± 5 kg m-2 ) were scanned (at 3 T) during exhale breath-hold and images used to generate body models. Seven of these subjects were also scanned during inhale. Simplifications of the coil and body models were first explored, and then finite-difference time-domain simulations were run with a typical eight-channel parallel transmit coil positioned over the abdomen. Simulations were used to generate 10 g averaged SAR (SAR10g ) maps across 100,000 phase settings, and the worst-case scenario 10 g averaged SAR (wocSAR10g ) was identified using trigonometric maximisation. The average maximum SAR10g across the 10 subjects with 1 W input power per channel was 1.77 W kg-1 . Hotspots were always close to the body surface near the muscle wall boundary. The wocSAR10g across the 10 subjects ranged from 2.3 to 3.2 W kg-1 and was inversely correlated to fat volume percentage (R = 8) and BMI (R = 0.6). The coefficient of variation values in SAR10g due to variations in subject geometry, respiration phase and realistic coil repositioning were 12%, 4% and 12%, respectively. This study found that the variability due to realistic coil repositioning was similar to the variability due to differing healthy subject geometries for abdominal imaging. This is important as it suggests that population-based modelling is likely to be more useful than individual modelling in setting safe thresholds for abdominal imaging.

Analysis of the metabolic profile of humans naturally exposed to RF-EM radiation.

INTRODUCTION: The world is experiencing exponential growth in communication, especially wireless communication. Wireless connectivity has recently become a part of everyone's daily life. Recent developments in low-cost, low-power, and miniature devices contribute to a significant rise in radiofrequency-electromagnetic field (RF-EM) radiation exposure in our environment, raising concern over its effect on biological systems. The inconsistent and conflicting research results make it difficult to draw definite conclusions about how RF-EM radiation affects living things. OBJECTIVES: This study identified two micro-environments based on their level of exposure to cellular RF-EM radiation, one with significantly less exposure and another with very high exposure to RF-EM radiation. Emphasis is given to studying the metabolites in the urine samples of humans naturally exposed to these two different microenvironments to understand short-term metabolic dysregulations. METHODS: Untargeted 1H NMR spectroscopy was employed for metabolomics analyses to identify dysregulated metabolites. A total of 60 subjects were recruited with 5 ml urine samples each. These subjects were divided into two groups: one highly exposed to RF-EM (n = 30) and the other consisting of low-exposure populations (n = 30). RESULTS: The study found that the twenty-nine metabolites were dysregulated. Among them, 19 were downregulated, and 10 were upregulated. In particular, Glyoxylate and dicarboxylate and the TCA cycle metabolism pathway have been perturbed. The dysregulated metabolites were validated using the ROC curve analysis. CONCLUSION: Untargeted urine metabolomics was conducted to identify dysregulated metabolites linked to RF-EM radiation exposure. Preliminary findings suggest a connection between oxidative stress and gut microbiota imbalance. However, further research is needed to validate these biomarkers and understand the effects of RF-EM radiation on human health. Further research is needed with a diverse population.

Radiofrequency identification tracking system (RFID) significantly improves blood bank inventory management and decreases staff work effort.

BACKGROUND: Before implementation of the radio frequency identification (RFID) system, there was a high loss rate of 4.0%-4.3% of red blood cell (RBC) units every year expiring on the shelf in our transfusion service laboratory. We introduced RFID technology to improve inventory management and the burden of work on the staff. The goal of this study was to evaluate the impact of RFID technology on the inventory management of RBC units and the staff workload in a transfusion service laboratory. STUDY DESIGN AND METHODS: Using an RFID system involves encoding RBC units with an RFID tag capturing information such as donor identification number, product code, blood type, expiration date, product volume, and negative antigen(s). Tag information is collected through retrofitted storage shelves linked to the RFID server. The study analyzed RBC usage by unit and by volume (mL) and staff work effort to carry out inventory management tasks before and after the implementation of the RFID system. RESULTS: Implementation of the RFID technology reduced the loss, or discard, of RBC units to less than 1% annually (a statistically significant change, p < .001). The RFID computer dashboard provides a constant visual update of the inventory, allowing technologists to have accurate product counts and reducing their work burden. DISCUSSION: Implementation of RFID technology substantially reduced RBC product loss, improved inventory management, and lessened staff work burden.

Micro-environmental personal radio-frequency electromagnetic field exposures in Melbourne: A longitudinal trend analysis.

BACKGROUND: A knowledge gap exists regarding longitudinal assessment of personal radio-frequency electromagnetic field (RF-EMF) exposures globally. It is unclear how the change in telecommunication technology over the years translates to change in RF-EMF exposure. This study aims to evaluate longitudinal trends of micro-environmental personal RF-EMF exposures in Australia. METHODS: The study utilised baseline (2015-16) and follow-up (2022) data on personal RF-EMF exposure (88 MHz-6 GHz) measured across 18 micro-environments in Melbourne. Simultaneous quantile regression analysis was conducted to compare exposure data distribution percentiles, particularly median (P50), upper extreme value (P99) and overall exposure trends. RF-EMF exposures were compared across six exposure source types: mobile downlink, mobile uplink, broadcast, 5G-New Radio, Others and Total (of the aforementioned sources). Frequency-specific exposures measured at baseline and follow-up were compared. Total exposure across different groups of micro-environment types were also compared. RESULTS: For all micro-environmental data, total (median and P99) exposure levels did not significantly change at follow-up. Overall exposure trend of total exposure increased at follow-up. Mobile downlink contributed the highest exposure among all sources showing an increase in median exposure and overall exposure trend. Of seven micro-environment types, five of them showed total exposure levels (median and P99) and overall exposure trend increased at follow-up.