Abstract:
:Evaluation of water diffusion in the brain has revealed both fast- and slow-diffusing water populations. It has been suggested that these populations represent extra- and intracellular water, respectively. We have identified and characterized both populations in the intracellular space of the Xenopus oocyte. We have also determined their T(1) and T(2) relaxation properties. The fast and slow intracellular populations have diffusion coefficients of 1.06 +/- 0.05 microm(2)/ms and 0.16 +/- 0.02 microm(2)/ms, respectively, with the fast fraction representing 89% +/- 1% of the total water signal. These values are quite similar to those for total water in brain and are observed in the absence of signal from the perfusate (extracellular) water population. Volumetric swelling (16% +/- 4%) of the oocyte in hypoosmotic media increased the diffusion coefficients of both intracellular populations (fast = 1.27 +/- 0.03 microm(2)/ms, slow = 0.22 +/- 0.02 microm(2)/ms), but did not change their relative signal fractions. This phenomenon runs counter to the effects observed in brain injury, following which the apparent diffusion coefficient (ADC) decreases 30-50%. The results presented herein suggest that this ADC decrease in brain occurs despite cell swelling, which by itself would be expected to induce an increase in intracellular diffusion coefficients.
journal_name
Magn Reson Medjournal_title
Magnetic resonance in medicineauthors
Sehy JV,Ackerman JJ,Neil JJdoi
10.1002/mrm.10301subject
Has Abstractpub_date
2002-11-01 00:00:00pages
765-70issue
5eissn
0740-3194issn
1522-2594journal_volume
48pub_type
杂志文章abstract:PURPOSE:To optimize radiofrequency (RF) pulses for the selective excitation of dissolved phase (129)Xe that take into account the very short T2*, while simultaneously, minimally exciting the much larger gas signal. METHODS:Numerical simulations of Shinnar le-Roux pulses and binomial coefficient composite-element pulse...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.25089
更新日期:2015-01-01 00:00:00
abstract::MR oximetry requires a T2 measurement that is accurate within 5% in vivo. Simple methods are susceptible to signal loss and tend to underestimate T2. Current methods utilize RF pulses or RF cycling patterns that prevent signal loss at each data acquisition. However, using these methods with imperfect pulses, T2 tends ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910380512
更新日期:1997-11-01 00:00:00
abstract::Tumor pH is physiologically important since it influences a number of processes relevant to tumorigenesis and therapy. Hence, knowledge of localized pH within tumors would contribute to understanding these processes. The destructiveness, poor spatial resolution, and poor signal-to-noise ratio (SNR) of current technolo...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/(sici)1522-2594(199904)41:4<743::aid-mrm13
更新日期:1999-04-01 00:00:00
abstract:PURPOSE:To develop the simultaneous acquisition of multiple voxels in localized MR spectroscopy (MRS) using sensitivity encoding, allowing reduced total scan time compared to conventional sequential single voxel (SV) acquisition methods. METHODS:Dual volume localization was used to simultaneously excite voxels in both...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.25718
更新日期:2015-09-01 00:00:00
abstract:PURPOSE:To improve the quality and speed of electron paramagnetic resonance imaging (EPRI) acquisition by combining a uniform sampling distribution with spinning gradient acquisition. THEORY AND METHODS:A uniform sampling distribution was derived for spinning gradient EPRI acquisition (uniform spinning sampling, USS) ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.24712
更新日期:2014-02-01 00:00:00
abstract:PURPOSE:To measure the apparent diffusion coefficients (ADC) of five main metabolites in the human brain at 3T with PRESS and STEAM, avoiding measurement biases because of cross-terms. Cross-terms arise from interactions between slice-selection and spoiler gradients in the localized spectroscopy sequence and the diffus...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.26969
更新日期:2018-06-01 00:00:00
abstract:PURPOSE:To develop a strategy for training a physics-guided MRI reconstruction neural network without a database of fully sampled data sets. METHODS:Self-supervised learning via data undersampling (SSDU) for physics-guided deep learning reconstruction partitions available measurements into two disjoint sets, one of wh...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.28378
更新日期:2020-12-01 00:00:00
abstract:PURPOSE:Previous work has evaluated the quality of different analytic methods for extracting relaxation times from magnitude imaging data exhibiting Rician noise. However, biexponential analysis of relaxation in tissue, including cartilage, and materials is of increasing interest. We, therefore, analyzed biexponential ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.25111
更新日期:2015-01-01 00:00:00
abstract::It has been suggested that orientational changes in the collagen network of articular cartilage account for the depthwise T2 anisotropy of MRI through the magic angle effect. To investigate the relationship between laminar T2 appearance and collagen organization (anisotropy), bovine osteochondral plugs (N = 9) were T2...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1218
更新日期:2001-09-01 00:00:00
abstract::Fe(III)meso-tetra(4-sulfonatophenyl)porphine (Fe-TPPS4) has been investigated as a potential pH-sensitive nuclear magnetic resonance (NMR) proton image contrast agent. Relaxation rates (1/T1 and 1/T2) of water protons were measured as a function of pH and concentration of Fe-TPPS4 in phosphate-buffered isotonic saline...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910050313
更新日期:1987-09-01 00:00:00
abstract::A reproducibility study of proton MR spectroscopic imaging ((1)H-MRSI) of the human brain was conducted to evaluate the reliability of an automated 3D in vivo spectroscopic imaging acquisition and associated quantification algorithm. A PRESS-based pulse sequence was implemented using dualband spectral-spatial RF pulse...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.21713
更新日期:2008-09-01 00:00:00
abstract::ECG-gated cardiac MRI in the mouse is hindered by many technical difficulties in ECG signal recording inside static and variable high magnetic scanner fields. The present study proposes an alternative robust method of acquiring auto-gated cardiac and respiratory cine images in mouse heart. In our approach, a motion sy...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.20815
更新日期:2006-03-01 00:00:00
abstract:PURPOSE:Reliable monitoring of tissue nicotinamide adenine dinucleotide (NAD+ ) concentration may provide insights on its roles in normal and pathological aging. In the present study, we report a 1 H MRS pulse sequence for the in vivo, localized 1 H MRS detection of NAD+ from the human brain. METHODS:Studies were carr...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.27971
更新日期:2020-03-01 00:00:00
abstract::Homogeneous soft tissue, as regards its magnetic relaxation properties, is well-modeled by solutions of cross-linked protein (see Koenig and Brown, Prog. NMR Spectr. 22, 487 (1991)). Interactions at the solute-solvent interface alter the hydrodynamics of solvent water, and also couple the solute and solvent proton Zee...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910300606
更新日期:1993-12-01 00:00:00
abstract::The potential of quantitative parameter images of the relaxation times T1 and T2, the proton density rho and the apparent diffusion coefficient (ADC) to characterize three different experimental rat brain tumors (F98 glioma, RN6 Schwannoma, and E376 neuroblastoma) was studied. All parameter values, as determined in hi...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910340608
更新日期:1995-12-01 00:00:00
abstract::Precise relaxation time (RT) measurements have been made, with a standard deviation of 3% for T1 and T2 in white matter in normal volunteers. This sets an upper limit to the instrumental random errors (imprecision). Achieving this precision requires careful adjustment and use of the imager. The wide variation in RTs s...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910110307
更新日期:1989-09-01 00:00:00
abstract::To understand whether the NO-dependent vasodilator L-arginine was effective upon a chronically hypertensive cerebral capillary endothelium, dynamic susceptibility contrast MRI was used to measure the relative cerebral blood volume (rCBV) changes in nonischemic spontaneously hypertensive rats (SHRs). rCBV was measured ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910390123
更新日期:1998-01-01 00:00:00
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
pub_type: 杂志文章
doi:10.1002/mrm.10358
更新日期:2002-12-01 00:00:00
abstract:PURPOSE:We propose a constrained optimization approach for designing parallel transmit (pTx) pulses satisfying all regulatory and hardware limits. We study the trade-offs between excitation accuracy, local and global specific absorption rate (SAR), and maximum and average power for small flip-angle pTx (eight channels)...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.24800
更新日期:2014-04-01 00:00:00
abstract::Accurate quantification of myocardial perfusion remains challenging due to saturation of the arterial input function at high contrast concentrations. A method for estimating the arterial input function directly from tissue curves in the myocardium that avoids these difficulties is presented. In this constrained altern...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.22809
更新日期:2011-08-01 00:00:00
abstract::MRS has considerable potential for the measurement of drug pharmacokinetics in vivo. In this study single- and double-resonance (31)P MRS was used to investigate the biodistribution, pharmacokinetics, and metabolism of ifosfamide following administration of 500 mg/kg ifosfamide in guinea pigs. (1)H-decoupling was foun...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.10540
更新日期:2003-08-01 00:00:00
abstract::This study presents the detection of [2-(13)C]glucose metabolism in the carboxylic/amide region in the human brain, and demonstrates that the cerebral metabolism of [2-(13)C]glucose can be studied in human subjects in the presence of severe hardware constraints of widely available 3 T clinical scanners and with low-po...
journal_title:Magnetic resonance in medicine
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doi:10.1002/mrm.22044
更新日期:2009-09-01 00:00:00
abstract:PURPOSE:To evaluate proton density fat fraction (PDFF) and R2* as markers of bone marrow composition and structure in inflamed bone in patients with spondyloarthritis. METHODS:Phantoms containing fat, water, and trabecular bone were constructed with proton density fat fraction (PDFF) and bone mineral density (BMD) val...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.26729
更新日期:2018-02-01 00:00:00
abstract::A method is described for multislice imaging by means of rf pulses which contain a multifrequency excitation spectrum. These pulses label each slice by an individual signal phase and allow the separation of the signals from all the slices by subsequent add/subtract procedures. The image sensitivity corresponds to the ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910060315
更新日期:1988-03-01 00:00:00
abstract:PURPOSE:To examine the detection sensitivity for the rapidly exchanging hydroxyl protons of D-glucose using the recently developed on-resonance variable delay multi-pulse (onVDMP) chemical exchange saturation transfer (CEST) technique. METHODS:The onVDMP method was applied for the detection of water signal changes upo...
journal_title:Magnetic resonance in medicine
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doi:10.1002/mrm.27364
更新日期:2019-01-01 00:00:00
abstract::Gadobutrol (Gd-Bt; Gadovist(R), Schering AG) is a 1-M Gadolinium (Gd)-based contrast agent. Its higher Gd concentration allows for reduction of injection volumes in first pass contrast-enhanced MR angiography (CE-MRA) and should increase bolus sharpness and image quality. However, ambivalent results were reported. In ...
journal_title:Magnetic resonance in medicine
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doi:10.1002/mrm.21345
更新日期:2008-01-01 00:00:00
abstract:PURPOSE:This study evaluates biochemical imbalances in a rat model that reflects dysfunctional pathways in migraine. The high sensitivity and spectral dispersion available to 1 H MRS at 21.1 T expands metabolic profiling in this migraine model to include lactate (Lac), taurine (Tau), aspartate, and Gly-a mixture of gly...
journal_title:Magnetic resonance in medicine
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doi:10.1002/mrm.26811
更新日期:2018-03-01 00:00:00
abstract:PURPOSE:To evaluate the role of true diffusion and flow-related pseudodiffusion in cerebral blood flow (CBF) quantification using arterial spin labeling (ASL) with single-shot or segmented 3D gradient and spin echo (GRASE) readouts. THEORY:The extended phase graph (EPG) algorithm, originally designed to model the effe...
journal_title:Magnetic resonance in medicine
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doi:10.1002/mrm.27058
更新日期:2018-08-01 00:00:00
abstract::The application of spectroscopy techniques to the study of normal and pathological tissue is currently limited by the difficulties of acquiring precisely localized spectra and analyzing the resulting, relatively low signal-to-noise data. Interpretation of multivoxel spectroscopy data is greatly facilitated by estimati...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910250109
更新日期:1992-05-01 00:00:00
abstract::The dependence of 1/T1 on the magnetic field strength (the relaxation dispersion) has been measured at 37 degrees C on autopsy samples of human brain gray and white matter at field strengths corresponding to proton Larmor frequencies between 10 kHz and 50 MHz (0.0002-1.2 T). Additional measurements of 1/T1 and 1/T2 ha...
journal_title:Magnetic resonance in medicine
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doi:10.1002/mrm.1910160212
更新日期:1990-11-01 00:00:00