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MRI image plane nonuniformity in evaluation of ferrous sulphate dosimeter gel (FeGel) by means of T1-relaxation time

Magnusson, Peter LU ; Bäck, S A LU and Olsson, L E LU (1999) In Magnetic Resonance Imaging 17(9). p.1357-70
Abstract

MR image nonuniformity can vary significantly with the spin-echo pulse sequence repetition time. When MR images with different nonuniformity shapes are used in a T1-calculation the resulting T1-image becomes nonuniform. As shown in this work the uniformity TR-dependence of the spin-echo pulse sequence is a critical property for T1 measurements in general and for ferrous sulfate dosimeter gel (FeGel) applications in particular. The purpose was to study the characteristics of the MR image plane nonuniformity in FeGel evaluation. This included studies of the possibility of decreasing nonuniformities by selecting uniformity optimized repetition times, studies of the transmitted and received RF-fields and studies of the effectiveness of the... (More)

MR image nonuniformity can vary significantly with the spin-echo pulse sequence repetition time. When MR images with different nonuniformity shapes are used in a T1-calculation the resulting T1-image becomes nonuniform. As shown in this work the uniformity TR-dependence of the spin-echo pulse sequence is a critical property for T1 measurements in general and for ferrous sulfate dosimeter gel (FeGel) applications in particular. The purpose was to study the characteristics of the MR image plane nonuniformity in FeGel evaluation. This included studies of the possibility of decreasing nonuniformities by selecting uniformity optimized repetition times, studies of the transmitted and received RF-fields and studies of the effectiveness of the correction methods background subtraction and quotient correction. A pronounced MR image nonuniformity variation with repetition and T1 relaxation time was observed, and was found to originate from nonuniform RF-transmission in combination with the inherent differences in T1 relaxation for different repetition times. The T1 calculation itself, the uniformity optimized repetition times, nor none of the correction methods studied could sufficiently correct the nonuniformities observed in the T1 images. The nonuniformities were found to vary considerably less with inversion time for the inversion-recovery pulse sequence, than with repetition time for the spin-echo pulse sequence, resulting in considerably lower T1 image nonuniformity levels.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Background Radiation, Ferrous Compounds, Gels, Magnetic Resonance Imaging, Phantoms, Imaging, Radiation Dosage, Radiometry, Reference Standards, Subtraction Technique, Time Factors
in
Magnetic Resonance Imaging
volume
17
issue
9
pages
14 pages
publisher
Elsevier
external identifiers
  • Scopus:0344182996
ISSN
0730-725X
DOI
10.1016/S0730-725X(99)00081-8
language
English
LU publication?
yes
id
afbee029-f673-4fd0-95a2-5545d9246508
date added to LUP
2016-08-16 12:14:57
date last changed
2016-08-23 13:50:58
@misc{afbee029-f673-4fd0-95a2-5545d9246508,
  abstract     = {<p>MR image nonuniformity can vary significantly with the spin-echo pulse sequence repetition time. When MR images with different nonuniformity shapes are used in a T1-calculation the resulting T1-image becomes nonuniform. As shown in this work the uniformity TR-dependence of the spin-echo pulse sequence is a critical property for T1 measurements in general and for ferrous sulfate dosimeter gel (FeGel) applications in particular. The purpose was to study the characteristics of the MR image plane nonuniformity in FeGel evaluation. This included studies of the possibility of decreasing nonuniformities by selecting uniformity optimized repetition times, studies of the transmitted and received RF-fields and studies of the effectiveness of the correction methods background subtraction and quotient correction. A pronounced MR image nonuniformity variation with repetition and T1 relaxation time was observed, and was found to originate from nonuniform RF-transmission in combination with the inherent differences in T1 relaxation for different repetition times. The T1 calculation itself, the uniformity optimized repetition times, nor none of the correction methods studied could sufficiently correct the nonuniformities observed in the T1 images. The nonuniformities were found to vary considerably less with inversion time for the inversion-recovery pulse sequence, than with repetition time for the spin-echo pulse sequence, resulting in considerably lower T1 image nonuniformity levels.</p>},
  author       = {Magnusson, Peter and Bäck, S A and Olsson, L E},
  issn         = {0730-725X},
  keyword      = {Background Radiation,Ferrous Compounds,Gels,Magnetic Resonance Imaging,Phantoms, Imaging,Radiation Dosage,Radiometry,Reference Standards,Subtraction Technique,Time Factors},
  language     = {eng},
  number       = {9},
  pages        = {1357--70},
  publisher    = {ARRAY(0x953f5d0)},
  series       = {Magnetic Resonance Imaging},
  title        = {MRI image plane nonuniformity in evaluation of ferrous sulphate dosimeter gel (FeGel) by means of T1-relaxation time},
  url          = {http://dx.doi.org/10.1016/S0730-725X(99)00081-8},
  volume       = {17},
  year         = {1999},
}