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Theoretical and experimental evaluation of phase-dispersion effects caused by brain motion in diffusion and perfusion MR imaging

Author:
  • Ronnie Wirestam
  • Dan Greitz
  • Carsten Thomsen
  • Sara Brockstedt
  • Magnus B. E. Olsson
  • Freddy Ståhlberg
Publishing year: 1996
Language: English
Pages: 348-355
Publication/Series: Journal of Magnetic Resonance Imaging
Volume: 6
Issue: 2
Document type: Journal article
Publisher: John Wiley & Sons

Abstract english

We investigated intravoxel phase dispersion caused by pulsatile brain motion in diffusion spin-echo pulse sequences. Mathematical models were used to describe the spatial and temporal velocity distributions of human brain motion. The spatial distribution of brain-tissue velocity introduces a phase spread over one voxel, leading to signal loss. This signal loss was estimated theoretically, and effects on observed diffusion coefficient and perfused capillary fraction were assessed. When parameters from a diffusion pulse sequence without motion compensation were used, and ECG triggering with inappropriate delay times was assumed, the maximal signal loss caused by brain-motion-induced phase dispersion was predicted to be 21%. This corresponds to a 95% overestimation of the diffusion coefficient, and the perfusion-fraction error was small. Corresponding calculations for motion-compensated pulse sequences predicted a 1% to 1.5% signal loss due to undesired phase dispersion, whereas experimental results indicated a signal loss related to brain motion of 4%.

Keywords

  • Radiology, Nuclear Medicine and Medical Imaging
  • Magnetic resonance
  • MR imaging
  • Diffusion
  • Brain motion
  • Phase dispersion
  • Perfusion

Other

Published
  • ISSN: 1522-2586
Freddy Ståhlberg
E-mail: freddy [dot] stahlberg [at] med [dot] lu [dot] se

Professor

Medical Radiation Physics, Lund

+46 46 17 31 19

+46 70 688 31 19

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Professor

Diagnostic Radiology, (Lund)

+46 46 17 70 30

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Project manager

MR Physics

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