Concepts in Magnetic Resonance Part A最新文献_第3页

Multispin Cross-Correlated Transverse Dipolar NMR Relaxation in Solution 溶液中的多自旋交叉相关横向偶极核磁共振弛豫

IF 0.6 4区化学

Concepts in Magnetic Resonance Part A Pub Date : 2022-04-12 DOI: 10.1155/2022/1617848

E. Zuiderweg

引用次数: 1

Groundwater Potential Assessment Using Vertical Electrical Sounding and Magnetic Methods: A Case of Adilo Catchment, South Nations, Nationalities and Peoples Regional Government, Ethiopia 利用垂直电测深和磁法评价地下水潜力:以阿迪洛流域为例，埃塞俄比亚南部国家、民族和人民地区政府

IF 0.6 4区化学

Concepts in Magnetic Resonance Part A Pub Date : 2021-12-08 DOI: 10.1155/2021/5424865

Mulugeta Markos, A. Saka, L. Jule, N. Nagaprasad, K. Ramaswamy

{"title":"Groundwater Potential Assessment Using Vertical Electrical Sounding and Magnetic Methods: A Case of Adilo Catchment, South Nations, Nationalities and Peoples Regional Government, Ethiopia","authors":"Mulugeta Markos, A. Saka, L. Jule, N. Nagaprasad, K. Ramaswamy","doi":"10.1155/2021/5424865","DOIUrl":"https://doi.org/10.1155/2021/5424865","url":null,"abstract":"Vertical electrical sounding and magnetic methods were carried out to assess groundwater potential in Adilo catchment, Kembata Tembaro Zone, South Nations, Nationalities and Peoples Regional Government, Main Ethiopian Rift. The data were acquired from eight VES points using Schlumberger electrode arrays with maximum half current electrode spacing (\u0000 \u0000 \u0000 AB\u0000 \u0000 /\u0000 2\u0000 =\u0000 500\u0000 \u0000 ) and 253 magnetic data points were analyzed. The qualitative analysis of VES data was accomplished by using curves, apparent resistivity, and pseudodepths, and the quantitative interpretations of the VES data were constructed by the VES data using IPI-Res3, IPI2Win, and surfer software and constructing geoelectric section along with profiles and lithological information from the borehole and Geosoft interpretation was used for magnetic data. The VES results of the data revealed five geoelectric layers which differ in degree of fracturing, weathering, and formation. The upward continued magnetic field map anomaly to 560 m illustrated northwestern to the southwest; areas have a low magnetic anomaly. Examining the potential aquifer of profile one’s geoelectric section, the horizons of layer four were better potential aquifers as the highly fractured and weathered ignimbrite zone of layer five of VES13 was 219 m deeper than the depths of the other VES points, and along with profile two geoelectric sections, the horizon of layer four VES23 layer five has the lowest resistivity with large thickness at a depth of 253 m. Thus, the low resistivity and the large thickness of these formations are an indication of the high yield of groundwater potential in the study area.","PeriodicalId":55216,"journal":{"name":"Concepts in Magnetic Resonance Part A","volume":"27 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2021-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90189612","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 5

What Are the Relative Intensities of the Components of NMR Spectral Multiplets from Quadrupolar Nuclei in Uniformly Anisotropic Media? 均匀各向异性介质中四极核磁共振波谱多态各组分的相对强度是什么?

IF 0.6 4区化学

Concepts in Magnetic Resonance Part A Pub Date : 2021-02-18 DOI: 10.1155/2021/8890478

S. Elliott, P. Kuchel

引用次数: 1

A Statistical Robust Approach to Design Parallel Transmit Radiofrequency Excitations in MRI 磁共振成像中平行发射射频激励设计的统计鲁棒方法

IF 0.6 4区化学

Concepts in Magnetic Resonance Part A Pub Date : 2020-09-18 DOI: 10.1155/2020/6018107

V. Gras, F. Mauconduit, N. Boulant

{"title":"A Statistical Robust Approach to Design Parallel Transmit Radiofrequency Excitations in MRI","authors":"V. Gras, F. Mauconduit, N. Boulant","doi":"10.1155/2020/6018107","DOIUrl":"https://doi.org/10.1155/2020/6018107","url":null,"abstract":"In MRI, at ultrahigh field, the use of parallel transmit radiofrequency (RF) arrays is very beneficial to better control spin excitation spatially. In that framework, the so-called “universal pulse” technique, proposed recently for head imaging at 7 tesla, gives access to “plug-and-play” nonadiabatic solutions exhibiting good robustness against intersubject variations in the resonant transmit fields. This new type of solution has been defined so far as the result of numerical pulse optimizations performed across a collection of RF field maps acquired on a small population sample (pulse design database). In this work, we investigate an alternative universal pulse design approach in the linear small tip angle regime whereby the database of RF field maps is first transformed into a second-order statistical model and which then exploits a statistical robust design formalism for the optimization of the RF and magnetic field gradient waveforms. Experimental validation with an eightfold transmit RF coil for 7 tesla brain imaging shows that this new approach brings some benefit in terms of computational efficiency. Hence, for a design database composed of 35 maps, the computation time initially of 50 min could be reduced down to 3 min. The proposed statistical approach thus enables integration of large databases, presumably necessary to ensure robust solutions. Finally, it provides means to compute flip angle statistics and, along with it, simple performance metrics for quality assurance (RF pulse performance) or guidance in the optimization of TX array architectures.","PeriodicalId":55216,"journal":{"name":"Concepts in Magnetic Resonance Part A","volume":"29 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2020-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81348387","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 4

Solution of the Bloch Equations including Relaxation 包含松弛的Bloch方程的解

IF 0.6 4区化学

Concepts in Magnetic Resonance Part A Pub Date : 2020-09-02 DOI: 10.1155/2020/8819956

E. Johnston

引用次数: 1

Lineshape of Magnetic Resonance and its Effects on Free Induction Decay and Steady-State Free Precession Signal Formation 磁共振线形及其对自由感应衰减和稳态自由进动信号形成的影响

IF 0.6 4区化学

Concepts in Magnetic Resonance Part A Pub Date : 2020-01-19 DOI: 10.1155/2020/5057386

C. Ziener, M. Uhrig, T. Kampf, V. Sturm, F. Kurz, S. Heiland, M. Bendszus, M. Pham, P. Jakob, H. Schlemmer, L. Buschle

引用次数: 4

Brain and Hepatic Glucose Utilization in Malarial Infection Does Not Depend on Cerebral Symptoms of the Disease 疟疾感染的脑和肝葡萄糖利用不依赖于疾病的脑症状

IF 0.6 4区化学

Concepts in Magnetic Resonance Part A Pub Date : 2019-12-19 DOI: 10.1155/2019/3542393

Soumita Ghosh, Arjun Sengupta, Shobhona Sharma, H. M. Sonawat

引用次数: 1

Magic Angle Spinning and Truncated Field Concept in NMR 核磁共振中的魔角旋转和截断场概念

IF 0.6 4区化学

Concepts in Magnetic Resonance Part A Pub Date : 2019-12-04 DOI: 10.1155/2019/5895206

J. Jenczyk

引用次数: 1

Quantitative Susceptibility Mapping of Magnetic Quadrupole Moments 磁四极矩的定量敏感性作图

IF 0.6 4区化学

Concepts in Magnetic Resonance Part A Pub Date : 2019-08-06 DOI: 10.1155/2019/7174937

Junghun Cho, Dong Zhou, Youngwook Kee, P. Spincemaille, Yi Wang

{"title":"Quantitative Susceptibility Mapping of Magnetic Quadrupole Moments","authors":"Junghun Cho, Dong Zhou, Youngwook Kee, P. Spincemaille, Yi Wang","doi":"10.1155/2019/7174937","DOIUrl":"https://doi.org/10.1155/2019/7174937","url":null,"abstract":"We modeled the magnetic field up to the quadrupole term to investigate not only the average susceptibility (dipole), but also the susceptibility distribution (quadrupole) contribution. Expanding the magnetic field up to the 2nd order provides the quadrupole (0th: monopole, 1st: dipole). Numerical simulations were performed to investigate the quadrupole contribution with subvoxel nonuniformity. Conventional dipole and our dipole + quadrupole models were compared in the simulation, the phantom and human brain. Furthermore, the quadrupole field was compared with the anisotropic susceptibility field in the dipole tensor model. In a nonuniformity case, numerical simulations showed a nonnegligible quadrupole field contribution. Our study showed a difference between the two methods in the susceptibility map at the edges; both the phantom and human studies showed sharper structural edges with the dipole + quadrupole model. Quadrupole moments showed contrast mainly at the structural boundaries. The quadrupole moment field contribution was smaller but nonnegligible compared to the anisotropic susceptibility contribution. Nonuniform and uniform source distributions can be separately considered by quadrupole expansion, which were mixed together in the dipole model. In the presence of nonuniformity, the susceptibility maps may be different between the two models. For a comprehensive field model, the quadrupole might need to be considered along with susceptibility anisotropy and microstructure effects.","PeriodicalId":55216,"journal":{"name":"Concepts in Magnetic Resonance Part A","volume":"99 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2019-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80955796","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Dual-Echo Arterial Spin Labeling for Brain Perfusion Quantification and Functional Analysis 双回声动脉自旋标记用于脑灌注定量及功能分析

IF 0.6 4区化学

Concepts in Magnetic Resonance Part A Pub Date : 2019-08-01 DOI: 10.1155/2019/5040465

A. Paschoal, F. F. Paiva, R. Leoni

{"title":"Dual-Echo Arterial Spin Labeling for Brain Perfusion Quantification and Functional Analysis","authors":"A. Paschoal, F. F. Paiva, R. Leoni","doi":"10.1155/2019/5040465","DOIUrl":"https://doi.org/10.1155/2019/5040465","url":null,"abstract":"Arterial Spin Labeling (ASL) is a noninvasive MRI-based method to measure cerebral blood flow (CBF). Recently, the study of ASL as a functional tool has emerged once CBF fluctuation comes from capillaries in brain tissue, giving a more spatially specific response when compared to the standard functional MRI method, based on the blood oxygenation level-dependent (BOLD) contrast. Although the BOLD effect could be desirable to study brain function, if one aims to quantify CBF, such effect is considered contamination that can be more attenuated if short TE value is used in the image acquisition. An approach that provides both CBF and function information in a simultaneous acquisition is the use of a dual-echo ASL (DE-ASL) readout. Our purpose was to evaluate the information provided by DE-ASL regarding CBF quantification and functional connectivity with a motor task. Pseudocontinuous ASL of twenty healthy subjects (age: 32.4 ± 10.2 years, 13 male) was acquired at a 3T scanner. We analyzed the influence of TE on CBF values and brain connectivity provided by CBF and concurrent BOLD (cc-BOLD) time series. Brain networks were obtained by the general linear model and independent component analysis. Connectivity matrices were generated using a bivariate correlation (Fisher Z values). No effect of the sequence readout, but significant effect of the TE value, was observed on gray matter CBF values. Motor networks with reduced extension and more connections with important regions for brain integration were observed for CBF data acquired with short TE, proving its higher spatial specificity. Therefore, it was possible to use a dual-echo readout provided by a standard commercial ASL pulse sequence to obtain reliable quantitative CBF values and functional information simultaneously.","PeriodicalId":55216,"journal":{"name":"Concepts in Magnetic Resonance Part A","volume":"1 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2019-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91021215","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1