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High-resolution maps of magnetization transfer with inherent correction for RF inhomogeneity and T1 relaxation obtained from 3D FLASH MRI

Helms, Gunther LU ; Dathe, Henning; Kallenberg, Kai and Dechent, Peter (2008) In Magnetic Resonance in Medicine 60(6). p.1396-1407
Abstract
An empirical equation for the magnetization transfer (MT) FLASH signal is derived by analogy to dual-excitation FLASH, introducing a novel semiquantitative parameter for MT, the percentage saturation imposed by one MT pulse during TR. This parameter is obtained by a linear transformation of the inverse signal, using two reference experiments of proton density and T1 weighting. The influence of sequence parameters on the MT saturation was studied. An 8.5-min protocol for brain imaging at 3T was based on nonselective sagittal 3D-FLASH at 1.25mm isotropic resolution using partial acquisition techniques (TR/TE/flipangle = 25ms/4.9ms/5° or 11ms/4.9ms/15° for the T1 reference). A 12.8 ms Gaussian MT pulse was applied 2.2 kHz off-resonance with... (More)
An empirical equation for the magnetization transfer (MT) FLASH signal is derived by analogy to dual-excitation FLASH, introducing a novel semiquantitative parameter for MT, the percentage saturation imposed by one MT pulse during TR. This parameter is obtained by a linear transformation of the inverse signal, using two reference experiments of proton density and T1 weighting. The influence of sequence parameters on the MT saturation was studied. An 8.5-min protocol for brain imaging at 3T was based on nonselective sagittal 3D-FLASH at 1.25mm isotropic resolution using partial acquisition techniques (TR/TE/flipangle = 25ms/4.9ms/5° or 11ms/4.9ms/15° for the T1 reference). A 12.8 ms Gaussian MT pulse was applied 2.2 kHz off-resonance with 540° flip angle. The MT saturation maps showed an excellent contrast in the brain due to clearly separated distributions

for white and gray matter and cerebrospinal fluid. Within the limits of the approximation (excitation <15°, TR/T1<<1) the MT term depends mainly on TR, the energy and offset of the MT pulse, but hardly on excitation and T1 relaxation. It is inherently compensated for inhomogeneities of receive and transmit RF fields. The MT saturation appeared to be a sensitive parameter to depict MS lesions and alterations of normal-appearing white matter. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Magnetic Resonance in Medicine
volume
60
issue
6
pages
1396 - 1407
publisher
Wiley Online Library
external identifiers
  • scopus:57149103503
ISSN
1522-2594
DOI
10.1002/mrm.21732
language
English
LU publication?
yes
id
ea83c489-8625-4f3f-8900-377082862bd0 (old id 8773645)
date added to LUP
2016-02-27 00:59:17
date last changed
2017-10-22 03:49:54
@article{ea83c489-8625-4f3f-8900-377082862bd0,
  abstract     = {An empirical equation for the magnetization transfer (MT) FLASH signal is derived by analogy to dual-excitation FLASH, introducing a novel semiquantitative parameter for MT, the percentage saturation imposed by one MT pulse during TR. This parameter is obtained by a linear transformation of the inverse signal, using two reference experiments of proton density and T1 weighting. The influence of sequence parameters on the MT saturation was studied. An 8.5-min protocol for brain imaging at 3T was based on nonselective sagittal 3D-FLASH at 1.25mm isotropic resolution using partial acquisition techniques (TR/TE/flipangle = 25ms/4.9ms/5° or 11ms/4.9ms/15° for the T1 reference). A 12.8 ms Gaussian MT pulse was applied 2.2 kHz off-resonance with 540° flip angle. The MT saturation maps showed an excellent contrast in the brain due to clearly separated distributions<br/><br>
for white and gray matter and cerebrospinal fluid. Within the limits of the approximation (excitation &lt;15°, TR/T1&lt;&lt;1) the MT term depends mainly on TR, the energy and offset of the MT pulse, but hardly on excitation and T1 relaxation. It is inherently compensated for inhomogeneities of receive and transmit RF fields. The MT saturation appeared to be a sensitive parameter to depict MS lesions and alterations of normal-appearing white matter.},
  author       = {Helms, Gunther and Dathe, Henning and Kallenberg, Kai and Dechent, Peter},
  issn         = {1522-2594},
  language     = {eng},
  number       = {6},
  pages        = {1396--1407},
  publisher    = {Wiley Online Library},
  series       = {Magnetic Resonance in Medicine},
  title        = {High-resolution maps of magnetization transfer with inherent correction for RF inhomogeneity and T1 relaxation obtained from 3D FLASH MRI},
  url          = {http://dx.doi.org/10.1002/mrm.21732},
  volume       = {60},
  year         = {2008},
}