Detail publikace

Testing the quality of magnetic gradient fields for studying self-diffusion processes by magnetic resonance methods

Originální název

Testing the quality of magnetic gradient fields for studying self-diffusion processes by magnetic resonance methods

Anglický název

Testing the quality of magnetic gradient fields for studying self-diffusion processes by magnetic resonance methods

Jazyk

en

Originální abstrakt

Imaging techniques based on the principle of nuclear magnetic resonance (NMR) rank with the most advanced methods for studying chemical and biological properties of substances. Their universality makes them particularly suited for use in a wide range of scientific branches. NMR has found significant application in medicine. The diffusion effects of water molecules in tissues reduce the magnitude of spin echo in NMR measuring methods. Based on the amplitude change in the image, the diffusion coefficients and their distribution in the specimen being measured can be calculated. MR images of an object weighted by diffusion coefficients require a defined sequence of gradient pulses and an accurate knowledge of their time behaviour. Methods for measuring the diffusion coefficients require the knowledge of the minimum length of leading and trailing edges, the defined magnitude of the magnetic field gradient being excited, and also the symmetry of positive and negative gradient pulses (the zero integral of pulses of the same magnitude with opposite polarity). To determine the above characteristics of the time behaviour of gradient pulses of both polarities a simple measuring method was developed and experimentally tested on a tomograph with 4.7 T induction of basic magnetic field. This method is based on the principle of measuring the instantaneous frequency of MR signal in the presence of a gradient pulse subsequent to exciting a thin defined layer of the specimen under examination outside the gradient field centre.

Anglický abstrakt

Imaging techniques based on the principle of nuclear magnetic resonance (NMR) rank with the most advanced methods for studying chemical and biological properties of substances. Their universality makes them particularly suited for use in a wide range of scientific branches. NMR has found significant application in medicine. The diffusion effects of water molecules in tissues reduce the magnitude of spin echo in NMR measuring methods. Based on the amplitude change in the image, the diffusion coefficients and their distribution in the specimen being measured can be calculated. MR images of an object weighted by diffusion coefficients require a defined sequence of gradient pulses and an accurate knowledge of their time behaviour. Methods for measuring the diffusion coefficients require the knowledge of the minimum length of leading and trailing edges, the defined magnitude of the magnetic field gradient being excited, and also the symmetry of positive and negative gradient pulses (the zero integral of pulses of the same magnitude with opposite polarity). To determine the above characteristics of the time behaviour of gradient pulses of both polarities a simple measuring method was developed and experimentally tested on a tomograph with 4.7 T induction of basic magnetic field. This method is based on the principle of measuring the instantaneous frequency of MR signal in the presence of a gradient pulse subsequent to exciting a thin defined layer of the specimen under examination outside the gradient field centre.

BibTex


@article{BUT43263,
  author="Karel {Bartušek} and Eva {Gescheidtová}",
  title="Testing the quality of magnetic gradient fields for studying self-diffusion processes by magnetic resonance methods",
  annote="Imaging techniques based on the principle of nuclear magnetic resonance (NMR) rank with the most advanced methods for studying chemical and biological properties of substances. Their universality makes them particularly suited for use in a wide range of scientific branches. NMR has found significant application in medicine. The diffusion effects of water molecules in tissues reduce the magnitude of spin echo in NMR measuring methods. Based on the amplitude change in the image, the diffusion coefficients and their distribution in the specimen being measured can be calculated. MR images of an object weighted by diffusion coefficients require a defined sequence of gradient pulses and an accurate knowledge of their time behaviour. Methods for measuring the diffusion coefficients require the knowledge of the minimum length of leading and trailing edges, the defined magnitude of the magnetic field gradient being excited, and also the symmetry of positive and negative gradient pulses (the zero integral of pulses of the same magnitude with opposite polarity). To determine the above characteristics of the time behaviour of gradient pulses of both polarities a simple measuring method was developed and experimentally tested on a tomograph with 4.7 T induction of basic magnetic field. This method is based on the principle of measuring the instantaneous frequency of MR signal in the presence of a gradient pulse subsequent to exciting a thin defined layer of the specimen under examination outside the gradient field centre.",
  address="IOP publishing",
  chapter="43263",
  institution="IOP publishing",
  journal="Measurement Science and Technology",
  number="17",
  volume="2006",
  year="2006",
  month="july",
  pages="2256--2262",
  publisher="IOP publishing",
  type="journal article in Web of Science"
}