Abstract：
:B(1) Field inhomogeneity and the relative effects of dielectric resonances are analyzed within the context of ultra high field MRI. This is accomplished by calculating the electromagnetic fields inside spherical phantoms and within a human head model in the presence and absence of an RF coil. These calculations are then compared to gradient echo and RARE images, respectively. For the spherical phantoms, plane incident wave analyses are initially presented followed by full wave finite difference time domain (FDTD) calculations. The FDTD methods are then utilized to examine the electromagnetic interactions between the TEM resonator and an anatomically detailed human head model. The results at 340 MHz reveal that dielectric resonances are most strongly excited in objects similar in size to the human head when the conducting medium has a high dielectric constant and a low conductivity. It is concluded that in clinical UFHMRI, the most important determinants of B(1) field homogeneity consist of 1) the RF coil design, 2) the interaction between the RF coil, the excitation source and the sample, and finally 3) the geometry and electrical properties of the sample.
journal_name
Magn Reson Imagingjournal_title
Magnetic resonance imagingauthors
Ibrahim TS,Lee R,Abduljalil AM,Baertlein BA,Robitaille PMdoi
10.1016/s0730-725x(01)00300-9subject
Has Abstractpub_date
2001-02-01 00:00:00pages
219-26issue
2eissn
0730-725Xissn
1873-5894pii
S0730-725X(01)00300-9journal_volume
19pub_type
杂志文章abstract：:Magnetic resonance imaging (MRI) has played an important role in the diagnosis and management of cancer since it was first developed, but other modalities also continue to advance and provide complementary information on the status of tumors. In the future, there will be a major continuing role for noninvasive imaging...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章,评审
doi：10.1016/j.mri.2011.02.003
更新日期：2011-06-01 00:00:00
abstract：:We implemented pseudo-continuous ASL (pCASL) with 2D and 3D balanced steady state free precession (bSSFP) readout for mapping blood flow in the human brain, retina, and kidney, free of distortion and signal dropout, which are typically observed in the most commonly used echo-planar imaging acquisition. High resolution...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2013.03.024
更新日期：2013-09-01 00:00:00
abstract：:A new and simple method for precise determination of lateral opposed treatment portals was developed and used in 17 patients. Compared to CT, MRI led to significant changes of portals in 59% (10/17) of cases. Individual shielding blocks could be precisely designed by use of our new method. MRI is the procedure of choi...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/0730-725x(91)90007-9
更新日期：1991-01-01 00:00:00
abstract：:Magnetic resonance imaging (MRI) and spectroscopy (MRS) have contributed considerably to clinical radiology, and a variety of MR techniques have been developed to evaluate pathological processes as well as normal tissue biology at the cellular and molecular level. However, in comparison to nuclear imaging, MRI has rel...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2016.12.008
更新日期：2017-05-01 00:00:00
abstract：PURPOSE:Time-of-flight (ToF) and phase contrast (PC) magnetic resonance angiographies (MRAs) are noninvasive applications to depict the cerebral arteries. Both approaches can image the cerebral vasculature without the administration of intravenous contrast. Therefore, it is used in routine clinical evaluation of cerebr...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2012.10.023
更新日期：2013-05-01 00:00:00
abstract：:Autoradiographic studies have shown that low dose ketamine produces increases in regional glucose utilisation and blood flow in the hippocampus, cerebral cortex, and olfactory lobe in the rat brain, probably due to antagonism at the NMDA receptor. Functional MRI using deoxyhaemoglobin contrast can be used to study cha...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/0730-725x(95)00010-e
更新日期：1995-01-01 00:00:00
abstract：:A regularization strategy is described for generalized autocalibrating partially parallel acquisition (GRAPPA) that allows successful calibration using a small number of autocalibration signals (ACS). The approach requires certain nonlinear relationships between the GRAPPA coefficients to be satisfied, which increases...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2008.05.005
更新日期：2009-01-01 00:00:00
abstract：:Peripancreatic fluid collections are among the common post pancreas transplant complications, which are mainly due to leakage from the anastomosis site to bowel and graft pancreatitis. Differentiation between these two entities is important because they are treated differently. In this case, secretin stimulated magnet...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2009.02.003
更新日期：2009-09-01 00:00:00
abstract：PURPOSE:Diffusional kurtosis imaging (DKI) is sensitive to the effects of signal noise due to strong diffusion weightings and higher order modeling of the diffusion weighted signal. A simple noise correction scheme is proposed to remove the majority of the noise bias in the estimated diffusional kurtosis. METHODS:Weig...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2014.08.028
更新日期：2015-01-01 00:00:00
abstract：:A phase encoding method for imaging of chemical shift or magnetic field distributions is described. The method utilizes the spin-echo principle and the time period between signal collection and excitation is constant but the time period between excitation and the 180 degrees pulse is varied by constant steps. The meth...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/0730-725x(85)90253-x
更新日期：1985-01-01 00:00:00
abstract：:The purpose of this study was to assess the benefits of a 3 T scanner and an eight-channel phased-array head coil for acquiring three-dimensional PRESS (Point REsolved Spectral Selection) proton (H-1) magnetic resonance spectroscopic imaging (MRSI) data from the brains of volunteers and patients with brain tumors rela...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2006.07.012
更新日期：2006-12-01 00:00:00
abstract：:Today, patients with alveolar rhabdomyosarcoma have a favorable prognosis with a survival rate of more than 80%, due to modern radiotherapy. However, those patients with secondary meningeal involvement are still afflicted with a mortality rate of 90% unless a different therapeutic approach is taken. We report a case o...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/0730-725x(93)90035-c
更新日期：1993-01-01 00:00:00
abstract：OBJECTIVE:This study aims to evaluate the applicability of using single-shot and multi-shot segmented diffusion-weighted imaging (DWI) techniques to support biopsy target localization in a cohort of targeted MRI-guided prostate biopsy patients. MATERIALS AND METHODS:Single-shot echo-planar diffusion-weighted imaging (...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2016.05.012
更新日期：2016-10-01 00:00:00
abstract：:The HASTE (half-Fourier acquisition single-shot turbo spin-echo) technique delivers images with T2-weighting in about half a second and could be ideal for fast dynamic studies when T2-weighting is needed. We evaluated cardiac-triggered HASTE to study cervical spine flexion/extension. The cervical spines of ten asympto...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/s0730-725x(98)00176-3
更新日期：1999-04-01 00:00:00
abstract：:The purpose of this study was to develop a novel intravascular loopless monopole antenna (ILMA) design specifically for imaging of small vessel walls. The ILMA consisted of an unshielded, low-friction guide wire and a tuning/matching box. The material of the guide wire was nitinol and it was coated with polyurethane. ...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2012.06.032
更新日期：2013-01-01 00:00:00
abstract：:We studied the effect of hydralazine on tumor blood volume fraction and microvascular random flow velocity magnitude by IVIM weighted MRI in conjunction with dynamic Gd-DTPA-Albumin enhanced MRI. Blood volume fraction maps were obtained from the dynamic Gd-DTPA-Albumin enhanced MRI measurements. The average blood volu...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/s0730-725x(01)00431-3
更新日期：2001-10-01 00:00:00
abstract：:Constrained energy minimization (CEM) has proven highly effective for hyperspectral (or multispectral) target detection and classification. It requires a complete knowledge of the desired target signature in images. This work presents "Unsupervised CEM (UCEM)," a novel approach to automatically target detection and cl...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2010.03.009
更新日期：2010-06-01 00:00:00
abstract：:Quantitative cerebral blood flow (CBF) values can be determined from residue function estimates obtained from magnetic resonance dynamic susceptibility contrast (DSC) perfusion studies using a variety of deconvolution approaches. However, there are significant differences between the CBF estimates obtained, difference...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2004.12.001
更新日期：2005-04-01 00:00:00
abstract：:Atherosclerotic plaques in the bifurcation of the carotid arteries can pose a significant health risk due to possible plaque rupture and subsequent stroke. The assessment of plaques, and evaluation of the risk they pose, can be performed with Black-Blood (BB) vessel wall magnetic resonance imaging. However, resolution...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2017.04.011
更新日期：2017-07-01 00:00:00
abstract：PURPOSE:To analyze several histopathological features and their possible correlations with whole lesion histogram analysis derived from ADC maps in meningioma. MATERIALS AND METHODS:The retrospective study involved 36 patients with primary meningiomas. For every tumor, the following histogram analysis parameters of ap...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2018.05.009
更新日期：2018-09-01 00:00:00
abstract：:The applicability of the synthetic manganese porphyrin MnTPPS as tumor-selective MRI-contrast agent for brain tumors was investigated quantitatively by in vivo relaxometry. To exclude toxic effects of side products, the purification method for MnTPPS was improved. As a result, MnTPPS+Cl- (free acid) with a purity of m...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/0730-725x(93)90007-z
更新日期：1993-01-01 00:00:00
abstract：:Dynamic contrast-enhanced MRI (DCE-MRI) was used to noninvasively evaluate the effects of AG-03736, a novel inhibitor of vascular endothelial growth factor (VEGF) receptor tyrosine kinases, on tumor microvasculature in a breast cancer model. First, a dose response study was undertaken to determine the responsiveness o...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2006.09.041
更新日期：2007-04-01 00:00:00
abstract：BACKGROUND:Since the advent of magnetic resonance imaging, metal artifacts have posed an important diagnostic problem in different fields of medicine. However, this has not been systematically studied in patients undergoing surgery for brain tumors. OBJECTIVE:This study was planned to assess whether metal artifacts ca...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2012.11.001
更新日期：2013-06-01 00:00:00
abstract：:NMR imaging and localized 1H spectroscopy of a variety of aquatic organisms in vivo is described for the first time. The practical consideration of life support, water volume, salinity, and anesthesia are discussed and solutions presented. Such animal studies shape our understanding of physiology, biochemistry, and bi...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/0730-725x(90)90253-x
更新日期：1990-01-01 00:00:00
abstract：:The goal of this study was to develop and evaluate high-resolution magnetic resonance spectroscopic imaging (MRSI) utilizing the gains in signal-to-noise ratio (SNR) provided by combining higher magnetic field with high-sensitivity phased-array (PA) coils. We investigated the maximum improvement in spatial resolution ...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2005.10.019
更新日期：2006-01-01 00:00:00
abstract：:The biodistribution and relative molar effectiveness of the ionic (GdCl3) and chelated (Gd-DTPA) forms of gadolinium (Gd) to enhance proton relaxation rates in rat kidney, liver and spleen were evaluated. Rats were given intravenous injections of either GdCl3 (100 mumol/kg) or Gd-DTPA (178 mumol/kg). Gd-DTPA was prima...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/0730-725x(87)90023-3
更新日期：1987-01-01 00:00:00
abstract：:Percentage of lipid content of 22 adrenal cortex lesions and their water proton longitudinal relaxation time were measured in vitro at 60 MHz. Although water relaxation times obtained on benign and malignant samples overlap each other, measurements of the percentage of lipids performed on the same tissues allow us to ...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/0730-725x(87)90123-8
更新日期：1987-01-01 00:00:00
abstract：PURPOSE:To prospectively compare image quality and reliability of a non-contrast, self-navigated 3D whole-heart magnetic resonance angiography (MRA) sequence with contrast-enhanced computed tomography angiography (CTA) for sizing of thoracic aortic aneurysm (TAA). METHODS:Self-navigated 3D whole-heart 1.5 T MRA was pe...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2020.12.003
更新日期：2021-02-01 00:00:00
abstract：:Fast magnetic resonance (MR) imaging provides a consistent and predictable appearance of vascular abnormalities as shown by four patients with thrombi, dissection and aneurysm. Fast MR images are obtained during breath-holding, resulting in an absence of respiratory motion artifacts. The time of MR study is much less ...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/0730-725x(88)90483-3
更新日期：1988-07-01 00:00:00
abstract：:Partial volume effects in proton magnetic resonance spectroscopy in the brain have been studied previously in terms of proper water concentration calculations, but there is a lack of disclosure in terms of voxel placement techniques that would affect the calculations. The purpose of this study is to facilitate a fully...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2013.04.001
更新日期：2013-09-01 00:00:00
