Abstract：
:When assessing liver iron content using relaxometry, an average relaxation rate (R1, R2 or R2*) is usually determined from a region of interest or the entire liver. This is commonly performed by fitting the signal decay in individual voxels to an appropriate relaxation function. The voxel-level parameters resulting from the fits are combined to determine the average relaxation rate, and an empirically derived calibration curve is used to convert this single value to iron content. The goal of this study was to compare the precision and accuracy of this voxel-wise fitting to an alternative method that relies on first averaging the signals from all voxels within the region of interest and then determining the relaxation rate from a single fit. Systematic differences were observed when both methods were applied to clinical images. Mathematical simulations were employed to determine which method provided more robust estimates of the true relaxation rate. The mathematical simulations were then expanded to include a range of conditions expected in typical relaxometry images. The results show that voxel-wise fitting skews the relaxation rate estimates and increases variance, particularly when the true relaxation rate is moderate to fast, as it would be in liver with high iron content. The potential impact of these results on clinical decisions is discussed.
journal_name
Magn Reson Imagingjournal_title
Magnetic resonance imagingauthors
Marro K,Otto R,Kolokythas O,Shimamura A,Sanders JE,McDonald GB,Friedman SDdoi
10.1016/j.mri.2010.11.005subject
Has Abstractpub_date
2011-05-01 00:00:00pages
497-506issue
4eissn
0730-725Xissn
1873-5894pii
S0730-725X(10)00396-6journal_volume
29pub_type
杂志文章abstract：:Noninvasive functional studies on human spinal cord by means of magnetic resonance imaging (MRI) are gaining attention because of the promising applications in the study of healthy and injured central nervous system. The findings obtained are generally consistent with the anatomic knowledge based on invasive methods, ...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章,评审
doi：10.1016/j.mri.2004.10.015
更新日期：2004-12-01 00:00:00
abstract：:T1 and T2 relaxation times are fundamental parameters for signal contrast behaviour in MRI. A number of ex vivo relaxometry studies have dealt with the magnetic field dispersion of T1. By means of multicenter study within the frame of the COMAC BME Concerted Action on Tissue Characterization by MRI and MRS, the in viv...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章,多中心研究
doi：10.1016/0730-725x(93)90202-o
更新日期：1993-01-01 00:00:00
abstract：:The application of MRI-visible paramagnetic tracers to reveal in vivo connectivity can provide important subject-specific information for multisite, multielectrode intracortical recordings in combined behavioral and physiology experiments. To establish the use of such tracers in the nonhuman primate, we recently compa...
journal_title：Magnetic resonance imaging
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doi：10.1016/j.mri.2005.12.031
更新日期：2006-05-01 00:00:00
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journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/0730-725x(93)90251-8
更新日期：1993-01-01 00:00:00
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journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/0730-725x(92)90420-5
更新日期：1992-01-01 00:00:00
abstract：:Geometric distortion in MR imaging predominantly arises from the inhomogeneity of the static field and the nonlinearity of the gradients. It is the purpose of this paper to analyse the object and machine related contributions to geometric distortion in order to determine which corrections are necessary for attaining a...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/0730-725x(92)90011-n
更新日期：1992-01-01 00:00:00
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journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2011.09.023
更新日期：2012-02-01 00:00:00
abstract：PURPOSE:To evaluate the correlation between the pancreatic exocrine insufficiency estimated by cine-dynamic MRCP using spatially selective IR pulse and the severity stages (modified Cambridge classification) based on morphological changes of the pancreatic duct in patients with suspected chronic pancreatitis. MATERIAL...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2017.12.007
更新日期：2018-05-01 00:00:00
abstract：:Magnetic resonance imaging (MRI) has been applied to assess kidney function in normal rats by monitoring the passage of the extracellular contrast agent GdDOTA. High-resolution images have been obtained using either the rapid acquisition with relaxation enhancement (RARE) or the snapshot pulse sequence. The latter was...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/s0730-725x(00)00134-x
更新日期：2000-06-01 00:00:00
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journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/s0730-725x(96)00162-2
更新日期：1996-01-01 00:00:00
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journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/s0730-725x(98)00130-1
更新日期：1998-11-01 00:00:00
abstract：:The ripening of the tomato fruit was delayed for several days (average 5 days) by a 1-day heat treatment at 42 degrees C. Ethylene production increased during the first 3 h, but, after 6 h inhibition was almost total in tomato fruit incubated at 42 degrees C. However, recovery of ethylene production was rapid if fruit...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/s0730-725x(98)00219-7
更新日期：1999-06-01 00:00:00
abstract：:Magnetic resonance imaging (MRI) has been used to characterize tissues in morphological studies. Here, 23Na NMR imaging was used to study the distribution in muscle of brine (5 M NaCl), injected before onset of rigor mortis. First, the distribution of brine was monitored in excised muscle from rabbits for 6 hr followi...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/0730-725x(94)92360-4
更新日期：1994-01-01 00:00:00
abstract：:Within the magnetic resonance imaging (MRI) community the trend is going to higher and higher magnetic fields, ranging from 1.5 T to 7 T, corresponding to Larmor frequencies of 63.8-298 MHz. Since for high-field MRI the magnetization increases with the applied magnetic field, the signal-to-noise-ratio increases as wel...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2012.06.014
更新日期：2013-02-01 00:00:00
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journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2008.01.014
更新日期：2008-07-01 00:00:00
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journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/s0730-725x(01)00267-3
更新日期：2001-04-01 00:00:00
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journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2012.07.004
更新日期：2013-02-01 00:00:00
abstract：:Susceptibility-weighted imaging (SWI) is a valuable technique for high-resolution imaging of brain vasculature that greatly benefits from the emergence of higher field strength MR scanners. Autocalibrating partially parallel imaging techniques can be employed to reduce lengthy acquisition times as long as the decrease...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2008.08.003
更新日期：2009-05-01 00:00:00
abstract：:Magic-angle sample spinning is one of the cornerstones in high-resolution NMR of solid and semisolid materials. The technique enhances spectral resolution by averaging away rank 2 anisotropic spin interactions, thereby producing isotropic-like spectra with resolved chemical shifts and scalar couplings. In principle, i...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2004.11.067
更新日期：2005-02-01 00:00:00
abstract：:Magnetic field gradients play a fundamental role in MR imaging and localized spectroscopy. The MRI experiment, in particular fast MRI, relies on precise gradient switching, which has become more demanding with the constantly growing number of fast imaging techniques. Here we present a simple MR method to measure the b...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2007.02.002
更新日期：2007-11-01 00:00:00
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journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2019.08.018
更新日期：2019-11-01 00:00:00
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journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/0730-725x(86)91068-4
更新日期：1986-01-01 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：:We present the case of a 44-year-old man who complained of cervical pain. He was treated with physiotherapy and analgetics. Because of persistent pain, computed tomography (CT) scan and MRI were performed. They revealed an osteolytic destruction of the fourth cervical vertebra. The patient was treated surgically for r...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章,评审
doi：10.1016/j.mri.2004.01.006
更新日期：2004-05-01 00:00:00
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journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/s0730-725x(01)00403-9
更新日期：2001-07-01 00:00:00
abstract：:The chain dynamics of short-chain perfluoropolyether melts confined in Vycor nanoporous media has been characterized by field cycling nuclear magnetic resonance relaxometry and the dipolar correlation effect. The slowdown of motions under confinement, leading to larger residual dipolar couplings, has been probed by lo...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2006.11.018
更新日期：2007-05-01 00:00:00
abstract：:Most modern techniques for functional magnetic resonance imaging (fMRI) rely on blood-oxygen-level-dependent (BOLD) contrast as the basic principle for detecting neuronal activation. However, the measured BOLD effect depends on a transfer function related to neurophysiological changes accompanying electrical neural ac...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2008.02.006
更新日期：2008-11-01 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：:Fricke-agarose gels have been irradiated with a proton beam. Then samples have been extracted at different depths with respect to the beam penetration distance, corresponding to different irradiation doses. Relaxation times T1 and T2, measured at 17 MHz, appear sensitive to this kind of radiation. In particular, T2 ex...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/s0730-725x(96)00380-3
更新日期：1997-01-01 00:00:00
abstract：BACKGROUND AND PURPOSE:The widespread propagation of synchronized neuronal firing in seizure disorders may affect cortical and subcortical brain regions. Diffusion tensor imaging (DTI) can noninvasively quantify white matter integrity. The purpose of this study was to investigate the abnormal changes of white matter in...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2010.03.046
更新日期：2010-11-01 00:00:00
