Abstract:
:Functional MR imaging (fMRI) of activation in the brain is one of the more demanding applications required of an NMR imaging instrument. Since the signal changes in activation imaging are quite small, any instrumental variations can easily compromise the fMRI contrast. The authors describe a simple method for measuring these scanner instabilities, which is implementable on all scanners, to determine whether instability is degrading the fMRI contrast-to-noise. In this method, a long time series of images is acquired with identical imaging parameters to the chosen fMRI scans, the fluctuations are measured as a function of region-of-interest (ROI) size, and compared with the single image SNR. By plotting these fluctuations versus ROI size, and comparing them with the theoretically approachable value, the impact of these fluctuations can be assessed. We also present a simplified version of the test, which can be implemented with minimal calculations.
journal_name
Magn Reson Medjournal_title
Magnetic resonance in medicineauthors
Weisskoff RMdoi
10.1002/mrm.1910360422subject
Has Abstractpub_date
1996-10-01 00:00:00pages
643-5issue
4eissn
0740-3194issn
1522-2594journal_volume
36pub_type
杂志文章abstract::For time-resolved background-subtracted contrast-enhanced magnetic resonance angiography, the bright and sparse arterial signal allows unique identification of contrast bolus arrival in the arteries. This article presents an automatic filtering algorithm using such arterial characterization for selecting arterial phas...
journal_title:Magnetic resonance in medicine
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doi:10.1002/mrm.10358
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abstract:PURPOSE:Magnetization transfer in white matter (WM) causes biexponential relaxation, but most quantitative T1 measurements fit data assuming monoexponential relaxation. The resulting monoexponential T1 estimate varies based on scan parameters and represents a source of variation between studies, especially at high fiel...
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journal_title:Magnetic resonance in medicine
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abstract::NMR relaxation times (T1 and T2) and the water content (WC) of in vitro rat lungs were measured during the course of endotoxin lung injury in rats. Measurements of normal lungs, untreated endotoxin-injured lungs, and endotoxin-injured lungs treated with methylprednisolone (MPSL) were compared. The untreated endotoxin ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910150204
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abstract::A novel tagging method is introduced that increases the spatial resolution of estimates of myocardial radial thickening. The separation of adjacent parallel tag planes is customized to match the expected motion of specific regions of the heart wall. In regions in which the tags increase their separation over systole (...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910390421
更新日期:1998-04-01 00:00:00
abstract:PURPOSE:The aim of the study was to investigate whether incorrectly compensated eddy currents are the source of persistent X-nuclear spectroscopy and imaging artifacts, as well as methods to correct this. METHODS:Pulse-acquire spectra were collected for 1 H and X-nuclei (23 Na or 31 P) using the minimum TR permitted o...
journal_title:Magnetic resonance in medicine
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更新日期:2020-12-04 00:00:00
abstract::A method of post-processing to enhance the image resolution of the distribution of free radical molecules obtained with continuous-wave electron paramagnetic resonance (CW-EPR) imaging is reported. The low spatial resolution of EPR imaging, which has created difficulties in biomedical applications, was overcome by the...
journal_title:Magnetic resonance in medicine
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abstract::Proton MR spectroscopy ((1)H-MRS) has been used for in vivo quantification of intracellular triglycerides within the sarcolemma. The purpose of this study was to assess whether breath-hold dual-echo in- and out-of-phase MRI at 3.0 T can quantify the fat content of the myocardium. Biases, including T(1), T*(2), and noi...
journal_title:Magnetic resonance in medicine
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更新日期:2010-04-01 00:00:00
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journal_title:Magnetic resonance in medicine
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更新日期:2012-04-01 00:00:00
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journal_title:Magnetic resonance in medicine
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更新日期:2020-06-01 00:00:00
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journal_title:Magnetic resonance in medicine
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更新日期:2015-02-01 00:00:00
abstract:PURPOSE:A generalized intravoxel incoherent motion (IVIM) model, called the GIVIM, was proposed to better account for complex perfusion present in the tissues having various vessels and flow regimes, such as the liver. THEORY AND METHODS:The notions of continuous pseudodiffusion variable as well as perfusion fraction ...
journal_title:Magnetic resonance in medicine
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doi:10.1002/mrm.26064
更新日期:2016-11-01 00:00:00
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journal_title:Magnetic resonance in medicine
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doi:10.1002/mrm.21822
更新日期:2009-01-01 00:00:00
abstract::The previously observed improvement in spectral resolution of tissue proton NMR with high-resolution magic angle spinning (HRMAS) was speculated to be due largely to freeze-thawing artifacts resulting from tissue storage. In this study, 12 human prostate samples were analyzed on a 14.1T spectrometer at 3 degrees C, wi...
journal_title:Magnetic resonance in medicine
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doi:10.1002/mrm.10645
更新日期:2003-12-01 00:00:00
abstract::An automatic fMRI protocol for the investigation of the human auditory cortex has been developed. For the activation of the auditory system, the scanner noise itself is the source of sound. Rapid switching of B0 gradients allows the generation of tones of defined frequencies and amplitude on a conventional scanner wit...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910400621
更新日期:1998-12-01 00:00:00
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journal_title:Magnetic resonance in medicine
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更新日期:2015-01-01 00:00:00
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journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910150307
更新日期:1990-09-01 00:00:00
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journal_title:Magnetic resonance in medicine
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更新日期:2018-03-01 00:00:00
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doi:10.1002/mrm.25415
更新日期:2015-08-01 00:00:00
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journal_title:Magnetic resonance in medicine
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更新日期:2008-07-01 00:00:00
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journal_title:Magnetic resonance in medicine
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更新日期:2020-05-01 00:00:00
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journal_title:Magnetic resonance in medicine
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更新日期:2003-06-01 00:00:00
abstract::NMRD profiles, the magnetic field dependence of the water proton longitudinal relaxation rates, have been acquired for two new diphosphonate-modified GdDTPA complexes currently under evaluation as relaxation agents for the MRI detection of soft-tissue calcifications. Fresh dilute solutions show profiles identical to t...
journal_title:Magnetic resonance in medicine
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更新日期:1991-01-01 00:00:00
abstract::Experiments were performed to determine whether changes in T2*-weighted MR images during and after hyperoxia differentiate tumors from normal tissue. Mammary adenocarcinomas implanted in the right hind limbs of rats were studied. Gradient echo images were obtained at 2 Tesla with an evolution time of 20 ms and a recyc...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
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更新日期:1995-03-01 00:00:00
abstract::Noninvasive investigation of aldose reductase activities in rat testis was performed using 3-fluoro-3-deoxy-D-glucose (3-FDG) and nuclear magnetic resonance (NMR) spectroscopy/imaging. Quantitative determination of testis aldose reductase activities, expressed as the sorbitol index, showed a value similar to that of b...
journal_title:Magnetic resonance in medicine
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更新日期:1993-04-01 00:00:00
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journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
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更新日期:2020-10-01 00:00:00
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journal_title:Magnetic resonance in medicine
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更新日期:2006-04-01 00:00:00
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journal_title:Magnetic resonance in medicine
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journal_title:Magnetic resonance in medicine
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