keyword
MENU ▼
Read by QxMD icon Read
search

Pulse radiofrequency

keyword
https://www.readbyqxmd.com/read/29350408/calibration-and-non-orthogonality-correction-of-three-axis-hall-sensors-for-the-monitoring-of-mri-workers-exposure-to-static-magnetic-fields
#1
Antoine Delmas, Lamia Belguerras, Nicolas Weber, Freddy Odille, Cédric Pasquier, Jacques Felblinger, Pierre-André Vuissoz
A Magnetic Resonance Imaging (MRI) scanner uses three different electromagnetic fields (EMF) to produce body images: a static permanent magnetic field (MF), several pulsed magnetic gradients, and a radiofrequency pulse. As a result, any occupation that includes an MRI exposes workers to a strong MF. The World Health Organization has now given the monitoring of occupational EMF exposure a high priority. One design for a low-cost, compact MF exposure monitor (« MR exposimeter ») uses a set of three orthogonally assembled Hall sensors...
January 19, 2018: Bioelectromagnetics
https://www.readbyqxmd.com/read/29341000/basic-pulse-sequences-in-magnetic-resonance-imaging
#2
Daniel Calle, Teresa Navarro
Magnetic resonance images are obtained by a combination of different radiofrequency pulses and gradient waveforms applied to the subject inside a magnetic field. There are multiple pulse sequences used in clinical and preclinical studies adjusted to whatever physician or researches want to analyze, from basic anatomic images to accurate diagnostic techniques as diffusion, perfusion, or functional imaging. In this chapter, we present the most used radiofrequency pulse combinations of the two groups of sequences available in magnetic resonance imaging: spin-echo and gradient-echo sequences...
2018: Methods in Molecular Biology
https://www.readbyqxmd.com/read/29340999/introduction-to-mri-physics
#3
Gary V Martinez
Magnetic resonance imaging (MRI) is an imaging technique derived from radiofrequency (RF) signals of proton that are magnetized by a strong magnetic field. These protons typically originate from water, fat, or metabolites. The application of RF pulses is used to excite the magnetization, whereas pulsed magnetic field gradients are used to provide spatial localization. This chapter describes the fundamental principles giving rise to MR images. Furthermore, the connection between relaxation and image contrast is discussed...
2018: Methods in Molecular Biology
https://www.readbyqxmd.com/read/29333099/pulsed-radiofrequency-applied-to-the-sciatic-nerve-improves-neuropathic-pain-by-down-regulating-the-expression-of-calcitonin-gene-related-peptide-in-the-dorsal-root-ganglion
#4
Hao Ren, Hailong Jin, Zipu Jia, Nan Ji, Fang Luo
Background: Clinical studies have shown that applying pulsed radiofrequency (PRF) to the neural stem could relieve neuropathic pain (NP), albeit through an unclear analgesic mechanism. And animal experiments have indicated that calcitonin gene-related peptide (CGRP) expressed in the dorsal root ganglion (DRG) is involved in generating and maintaining NP. In this case, it is uncertain whether PRF plays an analgesic role by affecting CGRP expression in DRG. Methods: Rats were randomly divided into four groups: Groups A, B, C, and D...
2018: International Journal of Medical Sciences
https://www.readbyqxmd.com/read/29330080/use-of-a-pulsed-radiofrequency-energy-device-peak-plasmablade%C3%A2-in-neuromodulation-implant-revisions
#5
I Ughratdar, K A Kawsar, R Mitchell, R Selway, K Ashkan
BACKGROUND: Battery replacement or revision surgery for neuromodulation implants is conventionally performed using sharp dissection. Meticulous dissection within thick scar tissue is vital to avoid damage to surrounding lead(s) which could result in more extensive revision surgery. Traditional electrosurgery devices are contraindicated as the emitted energy can be transferred to the hardware resulting in implant or tissue damage with severe consequent complications. OBJECTIVE: We report our experience and potential applications of a novel, pulsed monopolar radiofrequency energy device (PEAK PlasmaBlade™, Medtronic plc) which facilitates dissection around implants without the risk of damaging or transmitting energy through the system...
January 9, 2018: World Neurosurgery
https://www.readbyqxmd.com/read/29329442/conventional-radiofrequency-thermocoagulation-vs-pulsed-radiofrequency-neuromodulation-of-ganglion-impar-in-chronic-perineal-pain-of-nononcological-origin
#6
Hammad Usmani, G P Dureja, Roshan Andleeb, Nazia Tauheed, Naiyer Asif
Background: Chronic nononcological perineal pain has been effectively managed by ganglion Impar block. Chemical neurolysis, cryoablation, and radiofrequency ablation have been the accepted methods of blockade. Recently, pulsed radiofrequency, a novel variant of conventional radiofrequency, has been used for this purpose. Study Design: This was a prospective, randomized, double-blind study. Setting: Two different interventional pain management centers in India...
January 10, 2018: Pain Medicine: the Official Journal of the American Academy of Pain Medicine
https://www.readbyqxmd.com/read/29322616/development-of-methods-and-feasibility-of-using-hyperpolarized-carbon-13-imaging-data-for-evaluating-brain-metabolism-in-patient-studies
#7
Ilwoo Park, Peder E Z Larson, Jeremy W Gordon, Lucas Carvajal, Hsin-Yu Chen, Robert Bok, Mark Van Criekinge, Marcus Ferrone, James B Slater, Duan Xu, John Kurhanewicz, Daniel B Vigneron, Susan Chang, Sarah J Nelson
PURPOSE: Hyperpolarized carbon-13 (13 C) metabolic imaging is a noninvasive imaging modality for evaluating real-time metabolism. The purpose of this study was to develop and implement experimental strategies for using [1-13 C]pyruvate to probe in vivo metabolism for patients with brain tumors and other neurological diseases. METHODS: The 13 C radiofrequency coils and pulse sequences were tested in a phantom and were performed using a 3 Tesla whole-body scanner...
January 10, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29317362/lumbar-dorsal-root-ganglion-block-as-a-prognostic-tool-prior-to-pulsed-radiofrequency-a-randomized-prospective-and-comparative-study-on-cost-effectiveness
#8
Cheng-Chia Lee, Ching-Jen Chen, Chien-Chen Chou, Hsin-Yi Wang, Wen-Yuh Chung, Giia-Sheun Peng, Ching-Po Lin
OBJECTIVES: In the study, we discuss the predictive value and cost-effectiveness of dorsal root ganglion (DRG) blocks prior to using dorsal root ganglion pulsed radiofrequency (DRG-PRF) in the treatment of low back pain. METHODS: The study comprised 60 patients with low back pain who were randomly assigned into two groups. Patients in Group 1 were screened using DRG block prior to DRG-PRF treatment for responders. Patients in Group 2 underwent DRG-PRF treatment without DRG block...
January 6, 2018: World Neurosurgery
https://www.readbyqxmd.com/read/29317361/intraarticular-pulsed-radiofrequency-to-treat-refractory-lumbar-facet-joint-pain-in-patients-with-low-back-pain
#9
Min Cheol Chang, Yun-Woo Cho, Da Hyun Ahn, Kyung Hee Do
OBJECTIVE: Many treatment techniques have been used for refractory lumbar facet joint pain; however, their efficacy has been controversial. In this study, we investigated the clinical efficacy and safety of intraarticular pulsed radiofrequency for the treatment of refractory lumbar facet joint pain in patients with low back pain. METHODS: Twenty patients with refractory lumbar facet joint pain were recruited and each patient was treated using intraarticular pulsed radiofrequency...
January 6, 2018: World Neurosurgery
https://www.readbyqxmd.com/read/29275583/-clinical-application-of-oxycodone-combined-with-dexmedetomidine-in-percutaneous-ultrasound-guided-radiofrequency-ablation-of-hepatocellular-carcinomas
#10
H D Zhou, H F Jiang, Y J Zhu, J Fang
Objective: To explore the effects of oxycodone combined with dexmedetomidine in percutaneous ultrasound-guided radiofrequency ablation of hepatocellular carcinomas. Methods: Sixty patients who underwent percutaneous ultrasound-guided radiofrequency ablation of hepatocellular carcinomas were randomly divided into fentanyl group (group A) and oxycodone group( group B), with 30 patients in each group. Patients in group A were injected with fentanyl (2 μg/kg), and patients in group B were injected with oxycodone (0...
November 28, 2017: Zhonghua Yi Xue za Zhi [Chinese medical journal]
https://www.readbyqxmd.com/read/29275456/pulse-dose-radiofrequency-treatment-in-pain-management-initial-experience
#11
REVIEW
Christine Ojango, Mario Raguso, Roberto Fiori, Salvatore Masala
Radiofrequency procedures have been used for treating various chronic pain conditions for decades. These minimally invasive percutaneous treatments employ an alternating electrical current with oscillating radiofrequency wavelengths to eliminate or alter pain signals from the targeted site. The aim of the continuous radiofrequency procedure is to increase the temperature sufficiently to create an irreversible thermal lesion on nerve fibres and thus permanently interrupt pain signals. The pulsed radiofrequency procedure utilises short pulses of radiofrequency current with intervals of longer pauses to avert a temperature increase to the level of permanent tissue damage...
December 23, 2017: Skeletal Radiology
https://www.readbyqxmd.com/read/29274074/evaluation-of-subclinical-atherosclerosis-by-ultrasound-radiofrequency-data-technology-in-patients-with-familial-mediterranean-fever
#12
Hatice Kaplanoglu, Cem Özisler
OBJECTIVES: The aim of this study was to noninvasively demonstrate the presence of early risk associated with subclinical inflammatory activity in patients with familial Mediterranean fever (FMF) who had stable disease, using ultrasound (US) radiofrequency data technology. METHODS: A total of 110 participants, including 55 patients with FMF and 55 healthy control participants, were evaluated with Doppler US. The intima-media thickness and arterial stiffness were measured from bilateral common carotid arteries (CCAs) by the radiofrequency method...
December 23, 2017: Journal of Ultrasound in Medicine: Official Journal of the American Institute of Ultrasound in Medicine
https://www.readbyqxmd.com/read/29235992/avoiding-neuromuscular-stimulation-in-liver-irreversible-electroporation-using-radiofrequency-electric-fields
#13
Quim Castellví, Borja Mercadal, Xavier Moll, Dolors Fondevila, Anna Andaluz, Antoni Ivorra
Electroporation based treatments typically consist in applying high voltage dc pulses. As an undesired side effect, these dc pulses cause electrical stimulation of excitable tissues such as motor nerves. In the present in vivo study, it was explored the use of bursts of sinusoidal voltage in the frequency range from 50 kHz to 2 MHz to induce irreversible electroporation (IRE) whilst avoiding neuromuscular stimulation. Series of 100 dc pulses or sinusoidal bursts, both with an individual duration of 100 µs, were delivered to rabbit liver through thin needles in a monopolar electrode configuration and thoracic movements were recorded with an accelerometer...
December 13, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29230860/cardiac-gating-using-scattering-of-an-8-channel-parallel-transmit-coil-at-7t
#14
Sven H F Jaeschke, Matthew D Robson, Aaron T Hess
PURPOSE: To establish a cardiac signal from scattering matrix or scattering coefficient measurements made on a 7T 8-channel parallel transmit (pTx) system, and to evaluate its use for cardiac gating. METHODS: Measurements of the scattering matrix and scattering coefficients were acquired using a monitoring pulse sequence and during a standard cine acquisition, respectively. Postprocessing used an independent component analysis and gating feature identification. The effect of the phase of the excitation radiofrequency (RF) field ( B1+ shim) on the cardiac signal was simulated for multiple B1+ shim configurations, and cine images were reconstructed from both the scattering coefficients and electrocardiogram (ECG)...
December 11, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29219022/effectiveness-of-radiofrequency-hyperthermia-for-treating-cartilage-in-guinea-pigs-with-primary-osteoarthritis
#15
Kenji Takahashi, Hiroshi Nakamura, Hitoshi Ozawa, Sanshiro Hashimoto, Norio Iijima, Shimpei Higo, Hiroshi Watanabe, Yusuke Mochizuki, Shinro Takai
Objective Autophagy was reported to be essential for maintaining chondrocyte function, and reduced autophagy leads to osteoarthritis (OA). Previous studies showed involvement of heat shock stress in the control of autophagy in cells. This study sought to investigate the effect of hyperthermia on the expression of autophagy-related proteins in articular cartilage and the progression of naturally occurring OA in Hartley guinea pigs. Design Radiofrequency pulses of 13.56 MHz were applied to the animals' knees for 20 minutes to induce hyperthermia...
January 2018: Cartilage
https://www.readbyqxmd.com/read/29205480/a-z-gradient-array-for-simultaneous-multi-slice-excitation-with-a-single-band-rf-pulse
#16
Koray Ertan, Soheil Taraghinia, Alireza Sadeghi, Ergin Atalar
PURPOSE: Multi-slice radiofrequency (RF) pulses have higher specific absorption rates, more peak RF power, and longer pulse durations than single-slice RF pulses. Gradient field design techniques using a z-gradient array are investigated for exciting multiple slices with a single-band RF pulse. THEORY AND METHODS: Two different field design methods are formulated to solve for the required current values of the gradient array elements for the given slice locations...
December 4, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29201541/pulsed-radiofrequency-stimulation-suppresses-palmar-hyperhidrosis-in-an-animal-study
#17
Mu-Lien Lin, Tzu-Rung Huang, Ming-Chien Kao, Hung-Wei Chiu, Sheng-Chieh Lin, Fang-Chia Chang
Objectives: Palmar hyperhidrosis (PH) exhibits excessive and unpredictable sweating. The most effective treatment for permanent cure is the ablation of thoracic sympathetic ganglia innervating hands. However, sympathectomy of T2 sympathetic ganglion by clipping or cauterization causes irreversible nerve damage, and results in a compensatory hyperhidrosis (CH). We herein used the pulsed radiofrequency (PRF) stimulation to reversibly block sympathetic ganglion to treat PH and avoid CH. Material and Methods: A bipolar electrode was implanted into the right T2 sympathetic trunk by endoscopic surgery and PRF was delivered through the electrode...
November 2017: Brain and Behavior
https://www.readbyqxmd.com/read/29193250/design-of-universal-parallel-transmit-refocusing-kt-point-pulses-and-application-to-3d-t2-weighted-imaging-at-7t
#18
Vincent Gras, Franck Mauconduit, Alexandre Vignaud, Alexis Amadon, Denis Le Bihan, Tony Stöcker, Nicolas Boulant
PURPOSE: T2 -weighted sequences are particularly sensitive to the radiofrequency (RF) field inhomogeneity problem at ultra-high-field because of the errors accumulated by the imperfections of the train of refocusing pulses. As parallel transmission (pTx) has proved particularly useful to counteract RF heterogeneities, universal pulses were recently demonstrated to save precious time and computational efforts by skipping B1 calibration and online RF pulse tailoring. Here, we report a universal RF pulse design for non-selective refocusing pulses to mitigate the RF inhomogeneity problem at 7T in turbo spin-echo sequences with variable flip angles...
November 29, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29177139/high-field-in-vivo13c-magnetic-resonance-spectroscopy-of-brain-by-random-radiofrequency-heteronuclear-decoupling-and-data-undersampling
#19
Ningzhi Li, Shizhe Li, Jun Shen
In vivo13C magnetic resonance spectroscopy (MRS) is a unique and effective tool for studying dynamic human brain metabolism and the cycling of neurotransmitters. One of the major technical challenges for in vivo13C-MRS is the high radio frequency (RF) power necessary for heteronuclear decoupling. In the common practice of in vivo13C-MRS, alkanyl carbons are detected in the spectra range of 10-65 ppm. The amplitude of decoupling pulses has to be significantly greater than the large one-bond 1H-13C scalar coupling (1JCH = 125-145 Hz)...
2017: Frontiers in Physics
https://www.readbyqxmd.com/read/29159883/phase-sensitive-b1-mapping-effects-of-relaxation-and-rf-spoiling
#20
Jie Wen, Alexander L Sukstanskii, Dmitriy A Yablonskiy
PURPOSE: To develop a phase-based B1 mapping technique accounting for the effects of imperfect RF spoiling and magnetization relaxation. THEORY AND METHODS: The technique is based on a multi-gradient-echo sequence with 2 successive orthogonal radiofrequency (RF) excitation pulses followed by the train of gradient echoes measurements. We have derived a theoretical expression relating the MR signal phase produced by the 2 successive RF pulses to the B1 field and B0 -related frequency shift...
November 20, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
keyword
keyword
50451
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"