Three-dimensional Radiofrequency Research Articles

Stereo-electroencephalography-guided three-dimensional radiofrequency thermocoagulation for mesial temporal lobe epilepsy with hippocampal sclerosis: A retrospective study with long-term follow-up.

Stereo-electroencephalography-guided three-dimensional radiofrequency thermocoagulation (SEEG-3D RFTC) is a minimally invasive treatment for mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS). This study aimed to investigate the long-term prognosis after SEEG-3D RFTC treatment in patients with MTLE-HS. This single-center retrospective study included 28 patients with MTLE-HS treated with SEEG-3D RFTC from January 2016 to May 2018. Postoperative curative effects were evaluated using the Engel classification, and the patients were followed up for 5 years. The proportions of patients categorized as Engel I between 1 and 5 years after surgery were 72.41% (12 months after surgery), 67.86% (18 months after surgery), 62.07% (24 months after surgery), 50.00% (36 months after surgery), 42.86% (48 months after surgery), and 42.86% (60 months after surgery), respectively. Regarding long-term efficacy, based on the Engel classification, SEEG-3D RFTC showed room for improvement. This was the first study to evaluate the efficacy of SEEG-3D RFTC for MTLE-HS with long-term follow-up. SEEG-3D RFTC is a promising alternative for patients with MTLE-HS. This study explored the potential of stereoelectroencephalography-guided three-dimensional radiofrequency thermocoagulation, a minimally invasive approach, for treating medial temporal lobe epilepsy with hippocampal sclerosis. Involving 28 patients, the research tracked the treatment's success over five years using the Engel classification. Initial results were promising, with 72.41% of patients achieving the most favorable outcome (Engel I) at one year. While there was a gradual decrease in this proportion over time, 42.86% of patients maintained this positive outcome at five years, highlighting the treatment's potential for long-term efficacy.

Double-row dipole/loop combined array for human whole brain imaging at 7T.

Important issues in designing radiofrequency (RF) coils for human head imaging at ultra-high field (UHF; ≥7T) are the inhomogeneity and longitudinal coverage (along the magnet axis) of the transmit (Tx) RF field. Both the homogeneity and coverage produced by Tx volume coils can be improved by means of three-dimensional (3D) RF shimming, which requires the use of multirow Tx-arrays. In addition, according to recent findings of the ultimate intrinsic signal-to-noise ratio (UISNR) theory, the loop-only receive (Rx) arrays do not provide optimal SNR near the brain center at UHF. The latter can be obtained by combining complementary conductive structures carrying different current patterns (e.g., loops and dipole antennas). In this work, we developed, constructed, and evaluated a novel 32-element hybrid array design for human head imaging at 7T. The array consists of 16 transceiver loops placed in two rows circumscribing the head and 16 folded-end Rx-only dipoles positioned in the centers of loops. By placing all elements in a single layer, we increased RF power deposition into the tissue and, thus, preserved the Tx-efficiency. Using this hybrid design also simplifies the coil structure by minimizing the total number of array elements. The array demonstrated whole brain coverage, 3D RF shimming capability, and high SNR. It provided ~15% higher SNR near the brain center and, depending on the RF shim mode, from 20% to 40% higher Tx-efficiency than a common commercial head array coil.

Observation of efficacy and safety of stereotactic-EEG-guided three-dimensional radiofrequency thermocoagulation for the treatment of drug-resistant insular epilepsy

Objective: To investigate the safety and efficacy of stereotactic-EEG (SEEG)-guided radiofrequency thermocoagulation (RF-TC) with three-dimensional lesioning in the treatment of drug-resistant insular epilepsy. Methods: Seven patients with drug-resistant insular epilepsy who underwent SEEG-guided RF-TC with three-dimensional ablation at the Department of Neurosurgery of Xuanwu Hospital, Capital Medical University from February 2017 to June 2019 were retrospectively enrolled. Presurgical evaluation including semiology, EEG and imaging results suggested that the epileptogenic zone was located in the insular lobe. All patients underwent SEEG recording and three-dimensional RF-TC. Postoperative follow-up was conducted by outpatient visits or telephone, the clinical efficacy was evaluated based on Engel classification and the relevant complications were documented. Results: Seven patients were followed up at 18 months after surgery. Among them, 4 were seizure free (Engel ⅠA), 2 had nondisabling simple partial seizures (Engel ⅠB) and 1 achieved 75% decrease (Engel ⅢA) in seizure frequency. Postoperative complications occurred in 3 patients which included decreased sensation in the right lower extremity, decreased strength in the right upper extremity, glossolalia, decline in memory and comprehension. No permanent neurological dysfunction was detected. Conclusion: SEEG-guided RF-TC with three-dimensional lesioning is minimally invasive, safe and effective in the treatment of drug-resistant insular epilepsy and can serve as a complementary method for resection surgery.

Time-averaged potential for molecular ions in three-dimensional radio frequency traps

Time-averaged potential for molecular ions in three-dimensional radio frequency traps

Theoretical fractional formulation of a three-dimensional radio frequency ion trap (Paul-trap) for optimum mass separation

We investigate the dynamics of an ion confined in a Paul–trap supplied by a fractional periodic impulsional potential. The Cantor–type cylindrical coordinate method is a powerful tool to convert differential equations on Cantor sets from cantorian–coordinate systems to Cantor–type cylindrical coordinate systems. By applying this method to the classical Laplace equation, a fractional Laplace equation in the Cantor–type cylindrical coordinate is obtained. The fractional Laplace equation is solved in the Cantor–type cylindrical coordinate, then the ions is modelled and studied for confined ions inside a Paul–trap characterized by a fractional potential. In addition, the effect of the fractional parameter on the stability regions, ion trajectories, phase space, maximum trapping voltage, spacing between two signals and fractional resolution is investigated and discussed.

Dielectric and thermodynamic properties of Ba-doped photoetchable glasses for three dimensional RF microsystem packaging

Photoetchable glasses (PEGs) are employed in packaging of radio frequency (RF) microsystems. However, their widescale adoption has been limited by intrinsic high dielectric losses. The present study reports results of systematic investigation of dielectric and thermodynamic properties of Barium (Ba) ion substituted Li–Al–Si-based PEGs. It is demonstrated that UV absorption characteristics remain largely unchanged upon Ba ion doping. Crystallization behavior of PEGs were determined by digital scanning calorimetry. After annealing at different temperatures, the structure and morphology of precipitated crystal phases were analyzed by x-ray diffraction and electron microscopy. Results reveal that the optimal annealing temperature was 565 °C, after which dielectric properties were measured to experience a dielectric constant and minimum dielectric loss of 4.7 and 3 × 10−3, respectively. Concomitantly, the influence of temperature on dielectric properties at constant frequency was investigated. Raman spectroscopy analyses exhibit that the incorporation of Ba ions do not participate in structural changes but rather dissociate within the glass network as network modifiers, influencing the dielectric properties of Ba-doped PEG. The improvement in dielectric and thermodynamic properties demonstrated here confirms the value of PEGs as preferred interposer materials in three-dimensional RF microsystem packaging.

Three-dimensional numerical simulation of physical field distribution of radio frequency thermal plasma

Radio frequency (RF) thermal plasma involves abundant and complex physics. The understanding of the physical field distributions of the RF thermal plasma is helpful to its applications in industrial field. In this paper, an electro-thermal-magnetic-flow strong coupling mathematical and physical model of three-dimensional RF thermal plasma is established, the actual solenoid structure of the induction coil is considered, and a C++ code is developed for calculating the complex electromagnetic field in a customized version of the computational fluid dynamics commercial code FLUENT. The physical fields of RF thermal plasma, such as temperature field, flow field and electromagnetic field are studied. The electrical conductivity, thermal conductivity and viscosity distribution of the plasma are investigated. The results show that the physical field distribution of RF thermal plasma has an important non-axisymmetric three-dimensional effect due to the actual shape of the non-axisymmetric induction coil structure. The plasma discharge presents an annular distribution with a certain deflection angle. The distribution of plasma flow field shows a non-axisymmetric electromagnetic pump effect which is different from that of the two-dimensional model. The results have great guiding significance for optimizing and controlling the RF thermal plasma in various application areas.

Three port logic gate using forward volume spin wave interference in a thin yttrium iron garnet film

We demonstrate a logic gate based on interference of forward volume spin waves (FVSWs) propagating in a 54 nm thick, 100 μm wide yttrium iron garnet waveguide grown epitaxially on a garnet substrate. Two FVSWs injected by coplanar waveguides were made to interfere constructively and destructively by varying their phase difference, showing an XNOR logic function. The reflected and resonant waves generated at the edges of the waveguide were suppressed using spin wave absorbers. The observed isolation ratio was 19 dB for a magnetic field of ~2.80 kOe ( = 223 kA m−1) applied perpendicular to the film. The wavelength and device length were ~8.9 μm and ~53 μm, respectively. Further, the interference state of the SWs was analyzed using three-dimensional radio frequency simulations.

Normal-mode splitting in coupled high-Q microwave cavities

Three-dimensional radio frequency cavities demonstrate excellent frequency selectivity and, as such, are known for their use in RF filters. These cavities have potential applications in quantum information science, precision displacement metrology, and quantum electrodynamics. Additionally, coupled cavities that form a spectral doublet allow for parametric gain when incorporating mechanical elements. Here, we investigate normal-mode splitting in a pair of quarter-wave stub microwave cavities at room temperature and cryogenic environments in order to identify coupling mechanics for normal and superconducting systems. Superconducting quarter-wave stub cavities with a resonant frequency of 10 GHz are made from reactor-grade niobium and exhibit Q ranging from 105 to 109. We varied cavity-to-cavity coupling to observe several normal-mode splittings of increasing peak separation until we observed a mode crossing. The minimum observed peak separation was 7 MHz for room temperature tests and 200 kHz for cryogenic tests. We also report on values of an intrinsic quality factor for the tuning cavity as a dielectric rod is translated along its symmetry axis. The realization of coupled superconducting radio frequency (SRF) cavities of this type is a necessary step toward implementation of parametric SRF-mechanical gain.

Stereoelectroencephalography-guided three-dimensional radiofrequency thermocoagulation for the treatment of drug-resistant epilepsy

Objective To investigate the safety and efficacy of stereoelectroencephalography (SEEG)-guided radiofrequency thermocoagulation (RF-TC) with three-dimensional lesioning in the treatment of drug-resistant epilepsy. Methods Forty-eight patients with drug-resistant epilepsy who underwent SEEG-guided RF-TC with three-dimensional ablation at Neurosurgery Department of Xuanwu Hospital Capital Medical University from July 2015 to December 2017 were retrospectively enrolled into this study. There were 22 cases of mesial temporal lobe epilepsy (MTLE), 9 cases of hypothalamic hamartoma, 5 cases of frontal lobe epilepsy, 4 cases of insular lobe epilepsy, 1 case of periventricular nodular heterotopia, 1 case of tuberous sclerosis and 6 cases of multi-focal epilepsy. The clinical efficacy was evaluated based on the Engel grading system and the relevant complications were documented. Results The follow-up duration was 5-35 months, with an average of 16.3±7.3 months. The overall outcome was Engel Ⅰ in 23 (47.9%) cases, Engel Ⅱ in 12 (25.0%), Engel Ⅲ in 11 (22.9%) and Engel Ⅳ in 2 (4.2%). There were 71.9% (23/32) of patients who were seizure free at 1 year follow-up. The outcome was better in MTLE and hypothalamic hamartoma epilepsies, with Engel grade Ⅰ ratio of 59.1% (13/22) and 5/9 respectively. Multi-focal epilepsies (Engel grade Ⅲ: 4 out of 6 cases), frontal lobe epilepsies (Engel grade Ⅲ: 1 out of 5), Engel grade Ⅳ: 2 out of 5) had relatively poor curative effect. Transient complications following thermocoagulation occurred in 7 (14.6%) cases and permanent complications in 1 (2.1%). Conclusions SEEG-guided RF-TC with three-dimensional lesioning is minimally invasive, safe and effective in the treatment of drug-refractory epilepsy. Compared with other types of epilepsies, MTLE and hypothalamic hamartoma epilepsies have relatively better efficacy and RF-TC can be a complementary treatment for resective surgery. Key words: Epilepsy; Stereoelectroencephalography; Radiofrequency thermocoagulation; Three-dimensional

Three-dimensional radio-frequency transformers based on a self-rolled-up membrane platform

Radio-frequency (RF) integrated circuits are used for wireless communications and require transformers capable of transferring electrical energy at RF/microwave frequencies. Traditional on-chip RF transformer designs have complex fabrication schemes and offer limited performance scalability. Here we report on-chip RF/microwave transformers that are based on a self-rolled-up membrane platform. The monolithic nature and versatility of this platform allows us to create high-performance transformers while maintaining an ultra-compact device footprint and by using only planar processing. We also show that the performance of the three-dimensional RF transformers improves with scaling, which is in contrast to conventional planar designs. In particular, we observe a continuous rate of increase in the index of performance of our RF transformers as we scale up the turns ratio. This behaviour is attributed to the almost ideal mutual magnetic coupling inherent to the self-rolled-up membrane three-dimensional architecture.

Applications of the fractional calculus to study the physical theory of ion motion in a quadrupole ion trap.

In this article, fractional calculus has been applied to study the motion of ions in a three-dimensional radio frequency quadrupole ion trap; we have called this arrangement a fractional quadrupole ion trap. The main purpose of the article is to show that by controlling the fractional parameter of a trapped ion, one can gain a more efficient mass separation. In what follows, we will see that with decreasing the fractional parameter, we can achieve a smaller first stability region. Note that a small stability diagram will result in a good and acceptable mass separation. Various methods can be proposed to obtain a desired ion acceleration with a sufficient accuracy for good mass separation, which is similar to the one obtained by a fractional ion trap. Some of these methods are using the effects of a damping force, a magnetic field or both on the confinement of particles in the quadrupole ion trap. The first stability regions are plotted for all of the aforementioned methods, and simulation results are provided to compare them with those for the fractional case.

Electromagnetic coupling to centimeter-scale mechanical membrane resonators via RF cylindrical cavities

We present experimental and theoretical results for the excitation of a mechanical oscillator via radiation pressure with a room-temperature system employing a relatively low-(Q) centimeter-size mechanical oscillator coupled to a relatively low-Q standard three-dimensional radio-frequency (RF) cavity resonator. We describe the forces giving rise to optomechanical coupling using the Maxwell stress tensor and show that nanometer-scale displacements are possible and experimentally observable. The experimental system is composed of a 35 mm diameter silicon nitride membrane sputtered with a 300 nm gold conducting film and attached to the end of a RF copper cylindrical cavity. The RF cavity is operated in its mode and amplitude modulated on resonance with the fundamental drum modes of the membrane. Membrane motion is monitored using an unbalanced, non-zero optical path difference, optically filtered Michelson interferometer capable of measuring sub-nanometer displacements.

Ion dynamics in a Paul trap driven by various radio frequency waveforms

In this study we explore single ion dynamics in a Paul trap (three-dimensional radio frequency (RF) quadrupole ion trap – 3D QIT), driven by Sinusoidal, Rectangular, Sawtooth and Triangular RF waveforms. A molecular dynamic simulation code in Python has been written to explore ion dynamics in the trap. It is shown that various radio frequency waveforms produce various shift in ion oscillation in the trap. Furthermore phase space plots and the magnitude of the potential well depth for these various waveforms are given. Possible influences of these various RF waveforms have been summarized.

Multiparametric MR Imaging Depicts Glycosaminoglycan Change in the Achilles Tendon during Ciprofloxacin Administration in Healthy Men: Initial Observation.

To determine if quantitative magnetic resonance (MR) imaging techniques (sodium MR imaging, glycosaminoglycan [GAG] chemical exchange saturation transfer [CEST], and T2* mapping) could be used as potential markers for biochemical changes in the Achilles tendon induced by ciprofloxacin intake. The ethics committee of the Medical University of Vienna approved the protocol (number 1225/2012), and all patients gave written informed consent. Fourteen ankles from seven men (mean age, 32 years ± 12 [standard deviation]) were included in the study. All patients underwent 7-T MR imaging examinations of the Achilles tendon at baseline and 10 days and 5 months after ciprofloxacin intake. Sodium signal and T2* maps were acquired with the variable echo-time sequence and the GAG CEST values were acquired with a three-dimensional radiofrequency spoiled gradient-recalled-echo sequence. The mean sodium signal was significantly decreased by 25% in the whole tendon (from baseline to 10 days after ciprofloxacin intake, 130 arbitrary units [au] ± 8 to 98 au ± 5, respectively; P = .023) and returned to baseline after 5 months (116 au ± 10), as observed also at the tendon insertion (baseline, 10 days after ciprofloxacin intake, and 5 months after ciprofloxacin intake, 134 au ± 8, 105 au ± 5, and 119 au ± 9, respectively; P = .034). The mean GAG CEST value in the whole tendon was parallel to the sodium signal with a decrease from baseline to 10 days after ciprofloxacin intake, 4.74% ± 0.75 to 4.50% ± 0.23, respectively (P = .028) and an increase at 5 months after ciprofloxacin intake to 4.88% ± 1.02. In conclusion, this study demonstrates a ciprofloxacin-induced reversible reduction of the normalized sodium MR imaging signal and the GAG CEST effect in the Achilles tendon of healthy volunteers. Changes in sodium MR imaging and GAG CEST in men may reflect a decrease of GAG content in the Achilles tendon after ciprofloxacin intake.

A Bayesian Compressive Sensing Vehicular Location Method Based on Three-Dimensional Radio Frequency

In vehicular ad hoc networks (VANETs) safety applications, vehicular position is fundamental information to achieve collision avoidance and fleet management. Now, position information is comprehensively provided by global positioning system (GPS). However, in the dense urban, due to multipath effect and signal occlusion, GPS-based positioning method potentially fails to provide accurate position information. For this reason, an assistant approach has been presented in this paper by using three-dimensional radio frequency, such as time of arrival (TOA) and direction of arrival (DOA). With the goal of providing an efficient and reliable estimation of vehicular position in general traffic scenarios, we propose a hybrid TOA/DOA positioning method based on Bayesian compressive sensing (BCS), which benefits from the realization of vehicle-to-roadside wireless interaction with the dedicated short range communication. The effectiveness of the proposed approach is proved through extensive experiments in several scenarios where different signal configurations and the noise conditions are taken into account. Moreover, some comparative experiments are also performed to confirm the strength of our proposed approach.

Real‐time motion correction in two‐dimensional multislice imaging with through‐plane navigator

To develop a new real-time strategy to detect and correct for full three-dimensional rigid-body motion in two-dimensional multislice magnetic resonance imaging scans. Two through-plane navigator echoes collected on each imaging slice are used to reconstruct two orthogonal through-plane navigator projection images both perpendicular to the imaged slices, within each repetition time. Rotation/translation within each through-plane navigator image plane is detected using a regional image correlation measure that is robust against unaccounted orthogonal rotation and noise. An additional orbital navigator is used to detect rotation within the imaging plane and to reject intrarepetition time motion in real time. The efficacy of the proposed method was demonstrated with in vivo brain studies. The proposed real-time three-dimensional motion correction method does not introduce any additional three-dimensional radiofrequency excitation and does not require any additional hardware.

Reduced field-of-view excitation using second-order gradients and spatial-spectral radiofrequency pulses.

The performance of multidimensional spatially selective radiofrequency (RF) pulses is often limited by their long duration. In this article, high-order, nonlinear gradients are exploited to reduce multidimensional RF pulse length. Specifically, by leveraging the multidimensional spatial dependence of second-order gradients, a two-dimensional spatial-spectral RF pulse is designed to achieve three-dimensional spatial selectivity, i.e., to excite a circular region-of-interest in a thin slice for reduced field-of-view imaging. Compared to conventional methods that use three-dimensional RF pulses and linear gradients, the proposed method requires only two-dimensional RF pulses, and thus can significantly shorten the RF pulses and/or improve excitation accuracy. The proposed method has been validated through Bloch equation simulations and phantom experiments on a commercial 3.0T MRI scanner.

Analytical and Numerical Model Confrontation for Transfer Impedance Extraction in Three-Dimensional Radio Frequency Circuits

3D chip stacking is considered known to overcome conventional 2D-IC issues, using through silicon vias to ensure vertical signal transmission. From any point source, embedded or not, we calculate the impedance spread out; our ultimate goal will to study substrate noise via impedance field method. For this, our approach is twofold: a compact Green function or a Transmission Line Model over a multi-layered substrate is derived by solving Poisson’s equation analytically. The Discrete Cosine Transform (DCT) and its variations are used for rapid evaluation. Using this technique, the substrate coupling and loss in IC’s can be analyzed. We implement our algorithm in MATLAB; it permits to extract impedances between any pair of embedded contacts. Comparisons are performed using finite element methods.

Three-Dimensional Radiofrequency Tissue Tightening: A Proposed Mechanism and Applications for Body Contouring

Three-Dimensional Radiofrequency Tissue Tightening: A Proposed Mechanism and Applications for Body Contouring