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IF 0.9 4区医学

Concepts in Magnetic Resonance Part B-Magnetic Resonance Engineering Pub Date : 2016-09-23 DOI: 10.1002/cmr.b.21302

引用次数: 0

Subject-loaded quadrifilar helical-antenna RF coil with high B1+ field uniformity and large FOV for 3-T MRI 用于3-T MRI的高B1+场均匀性和大视场的主体负载四线螺旋天线射频线圈

IF 0.9 4区医学

Concepts in Magnetic Resonance Part B-Magnetic Resonance Engineering Pub Date : 2016-09-13 DOI: 10.1002/cmr.b.21326

Pranav S. Athalye, Nada J. Šekeljić, Milan M. Ilić, Alexey A. Tonyushkin, Branislav M. Notaroš

{"title":"Subject-loaded quadrifilar helical-antenna RF coil with high B1+ field uniformity and large FOV for 3-T MRI","authors":"Pranav S. Athalye, Nada J. Šekeljić, Milan M. Ilić, Alexey A. Tonyushkin, Branislav M. Notaroš","doi":"10.1002/cmr.b.21326","DOIUrl":"10.1002/cmr.b.21326","url":null,"abstract":"A novel method for excitation of RF B1 field in high-field (3-T) magnetic resonance imaging (MRI) systems using a subject-loaded quadrifilar helical antenna as an RF coil is proposed, evaluated, and demonstrated. Design, analysis, characterization, and evaluation of the novel coil when situated in a 3-T MRI bore and loaded with different phantoms are performed and cross-validated by extensive numerical simulations using multiple computational electromagnetics techniques. The results for the quadrifilar helical-antenna RF body coil show (a) strong field penetration in the entire phantoms; (b) excellent right-hand circular polarization (RCP); (c) high spatial uniformity of RCP RF magnetic field, B1+, throughout the phantoms; (d) large field of view (FOV); (e) good transmit efficiency; and (f) low local specific absorption rate (SAR). The examples show that the new RF coil provides substantially better B1+-field uniformity and much larger FOV than any of the previously reported numerical and experimental results for the existing RF coil designs at 3 T in literature that enable comparison. In addition, helical RF body coils of different lengths can, for instance, easily provide an excellent RCP and highly uniform B1+-field within the MRI maximum FOV length of 50 cm, and even 100 cm. The proposed MRI RF coil yields a remarkable improvement in the field uniformity in the longitudinal direction, for various phantoms, with comparable efficiency and SAR levels.","PeriodicalId":50623,"journal":{"name":"Concepts in Magnetic Resonance Part B-Magnetic Resonance Engineering","volume":"46B 3","pages":"106-117"},"PeriodicalIF":0.9,"publicationDate":"2016-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/cmr.b.21326","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77514040","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

A quadrature volume RF coil for vertical B0 field open MRI systems 垂直B0场开放MRI系统的正交体积射频线圈

IF 0.9 4区医学

Concepts in Magnetic Resonance Part B-Magnetic Resonance Engineering Pub Date : 2016-09-13 DOI: 10.1002/cmr.b.21327

Boguslaw Tomanek, Vyacheslav Volotovskyy, Randy Tyson, Donghui Yin, Jonathan Sharp, Barbara Blasiak

引用次数: 3

Eight-channel decoupled array for cervical spinal cord imaging at 3T: six-channel posterior and two-channel anterior array coil 8通道解耦阵列用于3T颈脊髓成像:6通道后路和2通道前路阵列线圈

IF 0.9 4区医学

Concepts in Magnetic Resonance Part B-Magnetic Resonance Engineering Pub Date : 2016-08-26 DOI: 10.1002/cmr.b.21325

Nabraj Sapkota, Bijaya Thapa, YouJung Lee, Taeho Kim, Erica F. Bisson, Lubdha M. Shah, John W. Rose, Eun-Kee Jeong

{"title":"Eight-channel decoupled array for cervical spinal cord imaging at 3T: six-channel posterior and two-channel anterior array coil","authors":"Nabraj Sapkota, Bijaya Thapa, YouJung Lee, Taeho Kim, Erica F. Bisson, Lubdha M. Shah, John W. Rose, Eun-Kee Jeong","doi":"10.1002/cmr.b.21325","DOIUrl":"10.1002/cmr.b.21325","url":null,"abstract":"The purpose of this study was to develop a dedicated high signal-to-noise ratio (SNR) radio frequency coil for cervical spinal cord (CSC) imaging without using the preamp decoupling technique. A novel eight-channel CSC array was constructed using butterfly, loop (circular), and rectangular elements. The adjacent elements were decoupled by the critical geometrical overlapping, and most non-adjacent elements were decoupled using the loop and butterfly elements. The performance of the proposed CSC coil was compared with the performance of the standard manufacturer's coil (Siemens' head, neck, and spine array) at 3T MRI system in T2-weighted images, diffusion tensor images, and ultrahigh-b diffusion-weighted images. In T2-weighted images, the SNR improvement of the eight-channel CSC coil was 1.4–2.0 times over the manufacturer's coil at the different levels of the CSC vertebrae. Higher contrast between white matter and gray matter was observed in the diffusion-weighted (b = 500 s/mm2) images and the fractional anisotropy maps obtained using the eight-channel CSC coil compared with the manufacturer's coil. The eight-channel CSC coil yielded 2.0 times higher SNR compared with the manufacturer's coil from the white matter region of the ultrahigh-b (b = 7348 s/mm2) radial diffusion-weighted images.","PeriodicalId":50623,"journal":{"name":"Concepts in Magnetic Resonance Part B-Magnetic Resonance Engineering","volume":"46B 2","pages":"90-99"},"PeriodicalIF":0.9,"publicationDate":"2016-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/cmr.b.21325","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86020646","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 5

Correction of B0 Drift Effects in Magnetic Resonance Thermometry using Magnetic Field Monitoring Technique 用磁场监测技术校正磁共振测温中的B0漂移效应

IF 0.9 4区医学

Concepts in Magnetic Resonance Part B-Magnetic Resonance Engineering Pub Date : 2016-07-22 DOI: 10.1002/cmr.b.21324

Daniel Hernandez, Ki Soo Kim, Eric Michel, Soo Yeol Lee

{"title":"Correction of B0 Drift Effects in Magnetic Resonance Thermometry using Magnetic Field Monitoring Technique","authors":"Daniel Hernandez, Ki Soo Kim, Eric Michel, Soo Yeol Lee","doi":"10.1002/cmr.b.21324","DOIUrl":"10.1002/cmr.b.21324","url":null,"abstract":"When magnetic resonance (MR) thermometry is performed for temperature monitoring during time-consuming thermal therapy like hyperthermia, tiny main magnetic field (B0) drifts may cause significant errors in temperature readings inside the human subject. We propose a correction method of B0 drift effects in MR thermometry, which is based on temperature-dependent proton resonance frequency shift (PRFS) of water molecules. We placed magnetic field monitoring (MFM) probes around the subject and we read the center frequency of MFM signals. By interpolating the center frequencies of MFM signals on the imaging slice, we computed phase correction maps for MR thermometry. We intermittently acquired MFM signals with performing MR thermometry at 3 Tesla during radiofrequency (RF) heating of a tissue-mimicking phantom. With the B0 drift effect correction, the temperature readings of MR thermometry maps became similar to the temperature readings of an optic fiber temperature sensor embedded at the center of the phantom. We believe the proposed correction method can be used for MRI-guided thermal therapy in which precise temperature monitoring is critical.","PeriodicalId":50623,"journal":{"name":"Concepts in Magnetic Resonance Part B-Magnetic Resonance Engineering","volume":"46B 2","pages":"81-89"},"PeriodicalIF":0.9,"publicationDate":"2016-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/cmr.b.21324","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87707008","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 8

Accuracy of the Magnetic Field Gradient Waveform Monitor Technique and Consequent Accuracy of Pre-Equalized Gradient Waveform 磁场梯度波形监测技术的精度与预均衡梯度波形的精度

IF 0.9 4区医学

Concepts in Magnetic Resonance Part B-Magnetic Resonance Engineering Pub Date : 2016-07-14 DOI: 10.1002/cmr.b.21323

Frédéric G. Goora, Bruce J. Balcom

{"title":"Accuracy of the Magnetic Field Gradient Waveform Monitor Technique and Consequent Accuracy of Pre-Equalized Gradient Waveform","authors":"Frédéric G. Goora, Bruce J. Balcom","doi":"10.1002/cmr.b.21323","DOIUrl":"10.1002/cmr.b.21323","url":null,"abstract":"The magnetic field gradient waveform monitor (MFGM) technique permits characterization of the temporal evolution of magnetic field gradients in magnetic resonance (MR) instruments (MRIs). Knowledge of the gradient waveform performance permits the development of further techniques, such as gradient waveform pre-equalization, that correct and optimize gradient waveform distortions due to eddy currents induced during the application of switched magnetic fields and other system limitations. The accuracy of the MFGM technique is important since the overall uncertainty of the gradient waveform measurement will propagate into an uncertainty in corrected gradient waveforms impacting the precision of the resulting MR/MRI measurements. The accuracy of MFGM is investigated through a treatment of the noise present in a MRI. A noisy receiver model provides the basis for characterization of the noise and permits examination of the overall impact of noise on the phase accumulated in a pure-phase encoded MR signal. Ultimately, a relationship between the signal-to-noise ratio of a measurement and the corresponding MFGM uncertainty is developed. The theoretical development is supported through simulation in conjunction with experimental results. The propagation of uncertainties to gradient waveform pre-equalization is also discussed.","PeriodicalId":50623,"journal":{"name":"Concepts in Magnetic Resonance Part B-Magnetic Resonance Engineering","volume":"46B 2","pages":"67-80"},"PeriodicalIF":0.9,"publicationDate":"2016-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/cmr.b.21323","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83324853","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 6

Design and Development of a General-Purpose Transmit/Receive (T/R) Switch for 3T MRI, Compatible for a Linear, Quadrature and Double-Tuned RF Coil 3T MRI通用收发开关的设计与开发，兼容线性、正交和双调谐射频线圈

IF 0.9 4区医学

Concepts in Magnetic Resonance Part B-Magnetic Resonance Engineering Pub Date : 2016-05-11 DOI: 10.1002/cmr.b.21321

Bijaya Thapa, Joshua Kaggie, Nabraj Sapkota, Deborah Frank, Eun-Kee Jeong

{"title":"Design and Development of a General-Purpose Transmit/Receive (T/R) Switch for 3T MRI, Compatible for a Linear, Quadrature and Double-Tuned RF Coil","authors":"Bijaya Thapa, Joshua Kaggie, Nabraj Sapkota, Deborah Frank, Eun-Kee Jeong","doi":"10.1002/cmr.b.21321","DOIUrl":"10.1002/cmr.b.21321","url":null,"abstract":"This work presents the design and development of a general-purpose T/R switch for MR imaging and spectroscopy, compatible with single and double-tuned RF coils using linear, quadrature, or both modes at a low cost and with minimum development time using simple electronic circuits. This T/R switch was demonstrated with a custom double-tuned 1H/31P transmit receive surface RF coils built for 31P MRS of a lamb's heart with surgically created congenital heart defects. Two passive trap circuits tuned to 1H and 31P frequencies fed from a common drive point were built to filter two different frequency T/R switches. The T/R switch was built for a 1H linear RF coil and 31P quadrature RF coil. This T/R switch design is easily modifiable to linear, quadrature and double-tuned RF coils of relatively wide range of frequencies, so as to enable imaging of proton and X-nuclei at 3T field. The performance of the custom T/R switch was tested with bench measurements of its isolation, insertion loss and switching time, under pulsed conditions, and on a phantom with a 3T magnet by comparing the signal-to-noise ratio with a commercial T/R switch. A high isolation, low insertion loss and fast switching time in the range of nanoseconds were obtained on the bench. Identical isolation was observed under pulsed conditions. An improvement of about 29% gain in signal-to-noise ratio was obtained with this T/R switch compared to the commercial T/R switch.","PeriodicalId":50623,"journal":{"name":"Concepts in Magnetic Resonance Part B-Magnetic Resonance Engineering","volume":"46B 2","pages":"56-65"},"PeriodicalIF":0.9,"publicationDate":"2016-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/cmr.b.21321","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80844133","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 16

Editorial Board and Table of Contents 编辑委员会和目录

IF 0.9 4区医学

Concepts in Magnetic Resonance Part B-Magnetic Resonance Engineering Pub Date : 2016-03-29 DOI: 10.1002/cmr.b.21297

引用次数: 0

NMR Concepts 核磁共振的概念

IF 0.9 4区医学

Concepts in Magnetic Resonance Part B-Magnetic Resonance Engineering Pub Date : 2016-03-29 DOI: 10.1002/cmr.b.21298

引用次数: 0

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IF 0.9 4区医学

Concepts in Magnetic Resonance Part B-Magnetic Resonance Engineering Pub Date : 2016-03-29 DOI: 10.1002/cmr.b.21299

引用次数: 0