Detail publikace

Errors in Diffusion Coefficients Measurement

Originální název

Errors in Diffusion Coefficients Measurement

Anglický název

Errors in Diffusion Coefficients Measurement

Jazyk

en

Originální abstrakt

The magnetic resonance (MR) imaging techniques of tomography and spectroscopy are exploited in many applications. The quality of dynamic behavior of gradient magnetic fields is one of the important properties of devices exploiting the phenomenon of magnetic resonance (MR) for imaging or diffusion measurement. A necessary precondition for the facilitation of MR instruments proper functioning consists in the maintenance of a high degree of homogeneity of the fundamental and gradient magnetic fields. Gradient changes induce eddy currents in the surrounding conducting arrangement, thus potentially causing image artifacts, localization errors, and signal distortion. While the use of actively shielded gradients has greatly reduced the magnitude of eddy currents, significant distortion often remains, mainly in the short time interval after the gradient is switched off. Residual eddy currents may require further reduction. This is frequently achieved by pre-emphasis correction in the relevant gradient channel and in the homogeneous B0 shim or by active shielded gradient coils. The rise time of the pulse of a magnetic field or its decrease to the level of non-homogeneity of the basic magnetic field should be as short as possible (< 100 us).

Anglický abstrakt

The magnetic resonance (MR) imaging techniques of tomography and spectroscopy are exploited in many applications. The quality of dynamic behavior of gradient magnetic fields is one of the important properties of devices exploiting the phenomenon of magnetic resonance (MR) for imaging or diffusion measurement. A necessary precondition for the facilitation of MR instruments proper functioning consists in the maintenance of a high degree of homogeneity of the fundamental and gradient magnetic fields. Gradient changes induce eddy currents in the surrounding conducting arrangement, thus potentially causing image artifacts, localization errors, and signal distortion. While the use of actively shielded gradients has greatly reduced the magnitude of eddy currents, significant distortion often remains, mainly in the short time interval after the gradient is switched off. Residual eddy currents may require further reduction. This is frequently achieved by pre-emphasis correction in the relevant gradient channel and in the homogeneous B0 shim or by active shielded gradient coils. The rise time of the pulse of a magnetic field or its decrease to the level of non-homogeneity of the basic magnetic field should be as short as possible (< 100 us).

BibTex


@inproceedings{BUT34368,
  author="Petr {Marcoň} and Karel {Bartušek}",
  title="Errors in Diffusion Coefficients Measurement",
  annote="The magnetic resonance (MR) imaging techniques of tomography and spectroscopy are exploited in many applications. The quality of dynamic behavior of gradient magnetic fields is one of the important properties of devices exploiting the phenomenon of magnetic resonance (MR) for imaging or diffusion measurement. A necessary precondition for the facilitation of MR instruments proper functioning consists in the maintenance of a high degree of homogeneity of the fundamental and gradient magnetic fields. Gradient changes induce eddy currents in the surrounding conducting arrangement, thus potentially causing image artifacts, localization errors, and signal distortion. While the use of actively shielded gradients has greatly reduced the magnitude of eddy currents, significant distortion often remains, mainly in the short time interval after the gradient is switched off. Residual eddy currents may require further reduction. This is frequently achieved by pre-emphasis correction in the relevant gradient channel and in the homogeneous B0 shim or by active shielded gradient coils. The rise time of the pulse of a magnetic field or its decrease to the level of non-homogeneity of the basic magnetic field should
be as short as possible (< 100 us).",
  booktitle="PIERS 2010 Cambridge, Progress In Electromagnetics Research Symposium Proceedings",
  chapter="34368",
  howpublished="electronic, physical medium",
  year="2010",
  month="july",
  pages="1035--1039",
  type="conference paper"
}