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Accuracy of q-space related parameters in MRI: Simulations and phantom measurements

  • Jimmy Lätt
  • Markus Nilsson
  • Carin Malmborg
  • Hannah Rosquist
  • Ronnie Wirestam
  • Freddy Ståhlberg
  • Daniel Topgaard
  • Sara Brockstedt
Publishing year: 2007
Language: English
Pages: 1437-1447
Publication/Series: IEEE Transactions on Medical Imaging
Volume: 26
Issue: 11
Document type: Journal article
Publisher: IEEE--Institute of Electrical and Electronics Engineers Inc.

Abstract english

The accuracy of q-space measurements was evaluated at a 3.0-T clinical magnetic resonance imaging (MRI) scanner, as compared with a 4.7-T nuclear magnetic resonance (NMR) spectrometer. Measurements were performed using a stimulated-echo pulse-sequence on n-decane as well as on polyethylene glycol (PEG) mixed with different concentrations of water, in order to obtain bi-exponential signal decay curves. The diffusion coefficients as well as the modelled diffusional kurtosis K-fit, were obtained from the signal decay curve, while the full-width at half-maximum (FWHM) and the diffusional kurtosis K were obtained from the displacement distribution. Simulations of restricted diffusion, under conditions similar to those obtainable with a clinical MRI scanner, were carried out assuming various degrees of violation of the short gradient pulse (SGP) condition and of the long diffusion time limit., The results indicated that an MRI system can not be used for quantification of structural sizes less than about 10 mu m by means of FWHM since the parameter underestimates the confinements due to violation of the SGP condition. However, FWHM can still be used as an important contrast parameter. The obtained kurtosis values were lower than expected from theory and the results showed that care must be taken when interpreting a kurtosis estimate deviating from zero.


  • Radiology, Nuclear Medicine and Medical Imaging
  • q-space
  • kurtosis magnetic resonance
  • displacement distribution
  • diffusion
  • imaging (MRI)


  • ISSN: 1558-254X
Freddy Ståhlberg
E-mail: freddy [dot] stahlberg [at] med [dot] lu [dot] se


Medical Radiation Physics, Lund

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MR Physics