Abstract:
PURPOSE:Magnetically labeled cells and tissue iron deposits provide qualitative means to detect and monitor cardiovascular and cerebrovascular diseases with magnetic resonance imaging. However, to quantitatively examine the extent of pathological micromorphological changes, detailed knowledge about microstructural parameters and relaxation times is required. METHODS:The complex geometrical arrangement of spherical magnetic perturbers is considered in an external magnetic field. They create a magnetic dipole field, whose corresponding spin-echo formation is investigated by analyzing the diffusion process in the dephasing volume. Quantitative predictions of the present analysis are compared with experimental data and empirical models. RESULTS:Single spin-echo relaxation times can be characterized by morphological parameters such as magnetic particle concentration and size as well as tissue diffusion coefficient and local magnetic susceptibility properties. As expected, no formation of a static dephasing plateau is observed in contrast to the gradient-echo relaxation time. Instead, the relaxation rate drops for large particle sizes and exhibits a prominent maximal value at intermediate sizes. These findings agree well with experimental data and previous theoretical results. CONCLUSION:Obtained results for the single spin-echo relaxation time allow to accurately quantify pathological processes in neurodegenerative disease and migration dynamics of magnetically labeled cells with the help of magnetic resonance imaging.
journal_name
Magn Reson Medjournal_title
Magnetic resonance in medicineauthors
Kurz FT,Kampf T,Heiland S,Bendszus M,Schlemmer HP,Ziener CHdoi
10.1002/mrm.25196subject
Has Abstractpub_date
2014-05-01 00:00:00pages
1888-95issue
5eissn
0740-3194issn
1522-2594journal_volume
71pub_type
杂志文章abstract::This work aimed to investigate the effects of administering Gd-DTPA on the BOLD effect, and to determine the feasibility of using this approach to measure fractional changes in blood volume and blood oxygenation on neuronal activation during a visual paradigm. A linear relationship between cortical R(2)(*) and the int...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.10340
更新日期:2003-01-01 00:00:00
abstract:PURPOSE:To develop a wideband cardiac perfusion pulse sequence and test whether it is capable of suppressing image artifacts in patients with a cardiac implantable electronic device (CIED), while not exceeding the specific absorption rate (SAR) limit (2.0 W/kg). METHODS:A wideband perfusion pulse sequence was develope...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.27458
更新日期:2019-02-01 00:00:00
abstract::This paper describes a method for correcting the chemical-shift artifacts in 19F NMR imaging of perfluoroctylbromide emulsion (PFOB) by utilizing the two spectral peaks of PFOB which have a long T2 value in conjunction with the Dixon method. Corrected images are obtained from the magnitude of the measured images using...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910230206
更新日期:1992-02-01 00:00:00
abstract::A modified Prony method (MPM) was applied to analyze the main signals present in spatially resolved 31P NMR spectra of MCF7 breast tumors implanted in nude mice. First, the method was tested on synthetic data to establish its limits of reliability. Its performance with respect to peak identification and quantification...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910380219
更新日期:1997-08-01 00:00:00
abstract::In spin echo imaging, magnetization is assigned to a location defined by its frequency of rotation. In the presence of a static magnetic field inhomogeneity, however, this location does not correspond to the true location of the magnetization. This paper describes a magnetic resonance imaging technique called phase co...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910330407
更新日期:1995-04-01 00:00:00
abstract:PURPOSE:Banding artifacts in images acquired by balanced steady-state free precession (bSSFP) remain a challenge in MRI as they considerably reduce image quality, and diagnostic value deteriorates accordingly. As the steady-state tolerates small shifts in frequency, it is possible to acquire frequency-modulated bSSFP. ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.26630
更新日期:2017-12-01 00:00:00
abstract::A new volume selection/spectral editing pulse sequence (VOSING) is presented. The features specific to the technique are that the volume selection and the editing intervals coincide and that no decoupling is necessary. The pulse sequence can be applied under both homo- and heteronuclear conditions. Phantom experiments...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910080108
更新日期:1988-09-01 00:00:00
abstract:PURPOSE:Dynamic glucose-enhanced (DGE)-MRI based on chemical exchange-sensitive MRI, that is, glucoCEST and gluco-chemical exchange-sensitive spin-lock (glucoCESL), is intrinsically prone to motion-induced artifacts because the final DGE contrast relies on the difference of images, which were acquired with a time gap o...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.28112
更新日期:2020-07-01 00:00:00
abstract::Rapid flow imaging was achieved with a partial field of view (pFOV) spiral motion-encoded technique. The FOV and the acquisition time were reduced by a factor of 2 by undersampling k-space. The pFOV spiral k-space trajectory aliased signals from outside a circular ring whose radius was inversely proportional to the di...
journal_title:Magnetic resonance in medicine
pub_type: 临床试验,杂志文章
doi:10.1002/mrm.20975
更新日期:2006-09-01 00:00:00
abstract::Formation of ternary complexes between Gd-DTPA, Gd-DTPA-BMA, and Gd-DOTA, used as contrast enhancement agents in MRI and the endogenously available carbonate and phosphate ions, has been demonstrated. The extent of ternary complex formation and its effect on the proton relaxation, measured at 9 MHz, rates is negligibl...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910380120
更新日期:1997-07-01 00:00:00
abstract:PURPOSE:To test the hypothesis that a noninvasive dynamic contrast enhanced MRI (DCE-MRI) derived interstitial volume fraction (ve ) and/or distribution volume (VD ) were correlated with tumor cellularity in cerebral tumor. METHODS:T1 -weighted DCE-MRI studies were performed in 18 athymic rats implanted with U251 xeno...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.24873
更新日期:2014-06-01 00:00:00
abstract::SENSitivity Encoding (SENSE) greatly enhances the quality of diffusion-weighted echo-planar imaging (EPI) by reducing blurring and off-resonance artifacts. Such improvement would also be desirable for diffusion tensor imaging (DTI), but measures derived from the diffusion tensor can be extremely sensitive to any kind ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.10184
更新日期:2002-07-01 00:00:00
abstract:PURPOSE:Atherosclerotic carotid plaques can be quantified in vivo by MRI. However, the accuracy in segmentation and quantification of components such as the thin fibrous cap (FC) and lipid-rich necrotic core (LRNC) remains unknown due to the lack of a submillimeter scale ground truth. METHODS:A novel approach was take...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.24905
更新日期:2014-07-01 00:00:00
abstract::We developed a quantitative magnetic resonance imaging method to permit a rapid assessment of brain water content during osmotic brain edema produced by intraperitoneal (ip) injection of distilled water. Fifteen minutes after water injection, the normalized mean image intensity (MIn) from a spin-echo pulse sequence (T...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910240107
更新日期:1992-03-01 00:00:00
abstract::In vivo effective relaxation rates in normal rat liver were evaluated for four dextran coated iron oxide agents: monocrystalline iron oxide nanocolloid (MION) with a mean particle diameter of 3.9 nm, a polycrystalline agent (PION) with a larger mean diameter of 12 nm, and these two agents labeled with the asialofetuin...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910370613
更新日期:1997-06-01 00:00:00
abstract:PURPOSE:Despite the increasing understanding of major depressive disorder (MDD) using neuroimaging techniques, the topological organization of anatomical networks underlying MDD remains unclear. METHODS:The topological organization of brain anatomical networks was explored using complex network approaches. Diffusion t...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.25036
更新日期:2014-11-01 00:00:00
abstract::Multiple-slice perfusion imaging by continuous arterial spin labeling (CASL) is made possible by amplitude modulation (AM) of the labeling RF pulse, but perfusion sensitivity is reduced relative to the single-slice technique. A computer model of the Bloch equations for velocity driven adiabatic fast passage was develo...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.20604
更新日期:2005-09-01 00:00:00
abstract:PURPOSE:Anisotropic transverse R2 (1/T2 ) relaxation of water proton is sensitive to cartilage degenerative changes. The purpose is to develop an efficient method to extract this relaxation metric in clinical studies. METHODS:Anisotropic R2 can be measured inefficiently by standard R2 mapping after removing an isotrop...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.27621
更新日期:2019-06-01 00:00:00
abstract::The soft tissue contrast obtained in fast imaging using rapidly repeated partial saturation sequences is usually based on differences in T1. We describe here an extension of the method which results in the development of clinically useful T2-based contrast. ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910040404
更新日期:1987-04-01 00:00:00
abstract::This study characterizes gains in sensitivity and spectral resolution of proton echo-planar spectroscopic imaging (PEPSI) with increasing magnetic field strength (B(0)). Signal-to-noise ratio (SNR) per unit volume and unit time, and intrinsic linewidth (LW) of N-acetyl-aspartate (NAA), creatine (Cr), and choline (Cho)...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.21067
更新日期:2006-12-01 00:00:00
abstract::It is demonstrated that a high-resolution (1)H NMR spectrum of excised rat liver can be obtained using the technique of magic angle turning (MAT) at a sample spinning rate of 1 Hz. A variant of the phase-corrected MAT (PHORMAT) pulse sequence that includes a water suppression segment was developed for the investigatio...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.10139
更新日期:2002-05-01 00:00:00
abstract::Magnetic resonance imaging has achieved clinical importance and has become the primary tool in the investigation of head, spinal cord, pelvis, cancellous bone, pericardium (with gating), gallbladder, lymph node masses, and very soon, in the evaluation of joints. In many areas, particularly with respiratory and ECG gat...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章,评审
doi:10.1002/mrm.1910020402
更新日期:1985-08-01 00:00:00
abstract:PURPOSE:Intracranial and intraspinal compliance are parameters of interest in the diagnosis and prediction of treatment outcome in patients with normal pressure hydrocephalus and other forms of communicating hydrocephalus. A noninvasive method to estimate the spinal cerebrospinal fluid (CSF) pulse wave velocity (PWV) a...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.28430
更新日期:2021-01-01 00:00:00
abstract::MRI evaluations of intramyocardial hemorrhage in acute infarction have relied on T(2) and T(2)(*) shortening only. We propose a more comprehensive evaluation of hemorrhagic infarction based on the concept that fluctuations in T(2) and T(1) relaxation in acute reperfused infarction will reflect transient edema and hemo...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.21079
更新日期:2006-12-01 00:00:00
abstract::Two single-shot volume imaging techniques are described. The first, single-echo echo-volume imaging, is essentially the echo-volume imaging (EVI) sequence suggested by Mansfield (J. Phys. C. 10, L55 (1977)). The second is a multi-spin-echo approach in which one plane of k-space is collected during each spin echo. In b...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910320518
更新日期:1994-11-01 00:00:00
abstract:PURPOSE:Cross-relaxation imaging (CRI) is a family of quantitative magnetization transfer techniques that utilize images obtained with off-resonance saturation and longitudinal relaxation rate (R1) maps reconstructed by the variable flip angle (VFA) method. It was demonstrated recently that a significant bias in an app...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.24677
更新日期:2014-02-01 00:00:00
abstract::Functional magnetic resonance imaging in real time is an emerging tool for the assessment of dynamic changes in brain activation. The short response latency (tens of seconds) renders the technique more sensitive to motion artifacts. Motion correction in real time requires computationally efficient algorithms which can...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/1522-2594(200101)45:1<167::aid-mrm1023>3.0
更新日期:2001-01-01 00:00:00
abstract::The eigenimage filter was used to evaluate the results of a MRI study of cerebral ischemia in a rat model. This linear filter segments a desired feature in an image sequence from other features which may interfere with its observation. The animals were imaged temporally, after occlusion of the middle cerebral artery, ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910260207
更新日期:1992-08-01 00:00:00
abstract::T2 measurements of 31P NMR signals of ATP using the Hahn 90 degrees-180 degrees spin-echo sequence imply difficulties whenever the 180 degrees pulse angle is not completely perfect. The reason for this finding is the crucial influence of the J-couplings of the ATP signals which result in intensity modulations and cons...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910300122
更新日期:1993-07-01 00:00:00
abstract::A combined carbogen ultrasmall superparamagnetic iron oxide (USPIO) imaging protocol was developed and applied in vivo in two murine colorectal tumor xenograft models, HCT116 and SW1222, with established disparate vascular morphology, to investigate whether additional information could be extracted from the combinatio...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.22779
更新日期:2011-07-01 00:00:00