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Ronnie Wirestam

Professor

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Quantitative diffusion coefficient maps using fast spin-echo MRI

Författare

  • Sara Brockstedt
  • C Thomsen
  • Ronnie Wirestam
  • Stig Holtås
  • Freddy Ståhlberg

Summary, in English

In this work, we have evaluated the performance of a diffusion-sensitive fast spin-echo (FSE) pulse sequence. The proposed pulse sequence utilises velocity-compensating diffusion-encoding gradients and includes the collection of navigator echoes. Spoiler gradients were inserted in the slice-selecting direction to minimise effects from stimulated echoes. Calculations of the b values showed that cross-terms between imaging gradients and diffusion gradients only led to a marginal increase of b values. Pixel-wise calculation of apparent diffusion coefficient (ADC) maps was performed numerically, considering cross-terms between diffusion-encoding and imaging gradients. The sequences investigated used echo train lengths of 16, 8 and 4 echoes and were encoded in either the slice-, frequency- or phase-encoding direction. In order to allow for higher b values a pulse-sequence version using non-motion compensating diffusion-encoding gradients was written. Phantom measurements were performed and the diffusion coefficients of water and acetone were reasonable. Seven healthy volunteers (age 28-50 years) were examined and apparent diffusion coefficient values agreed well with expected values. Diffusion-weighted images, apparent diffusion coefficient maps and images corresponding to the trace of the diffusion tensor of good quality were retrieved in vivo.

Avdelning/ar

  • Medicinsk strålningsfysik, Lund
  • Diagnostisk radiologi, Lund

Publiceringsår

1998

Språk

Engelska

Sidor

877-886

Publikation/Tidskrift/Serie

Magnetic Resonance Imaging

Volym

16

Issue

8

Dokumenttyp

Artikel i tidskrift

Förlag

Elsevier

Ämne

  • Radiology, Nuclear Medicine and Medical Imaging

Nyckelord

  • Navigator echoes Article Outline
  • Phase correction
  • Motion-compensating gradients
  • Diffusion
  • Fast spin-echo

Status

Published

ISBN/ISSN/Övrigt

  • ISSN: 1873-5894