Measurements and modeling of long range 3He diffusion in the lung using a "slice-washout" method

Stanislao Fichele, Martyn N J Paley, Neil Woodhouse, Paul D Griffiths, Edwin J R van Beek, Jim M Wild

Research output: Contribution to journalArticlepeer-review

Abstract

In healthy lung tissue, pulsed-gradient-spin-echo (PGSE) methods reveal apparent diffusion coefficients (ADC) of the order 0.20 cm2 s(-1); for diffusion times of approximately 2 ms. For these short diffusion times the ADC is only sensitive to structures approximately (2Dt)1/2 approximately 0.6mm in size. Recent work, using magnetic tagging of the longitudinal magnetization has revealed much smaller ADC values for longer length scales. In this work, the in vivo ADC from within the air-spaces, was measured using a new technique. The signal from a series of images was analyzed from a slice that was repeatedly imaged. Diffusion tends to "top-up" the non-renewable polarization within the slice, which leads to a non-exponential decay in image signal. Image data were compared to 1D finite-difference simulations of diffusion to calculate a long range ADC value. The results yield values of the order 0.034 cm2 s(-1), which are nearly an order of magnitude smaller than those reported by PGSE measurements at shorter diffusion times.

Original languageEnglish
Pages (from-to)28-33
Number of pages6
JournalJournal of Magnetic Resonance
Volume174
Issue number1
DOIs
Publication statusPublished - May 2005

Keywords

  • Algorithms
  • Computer Simulation
  • Diffusion Magnetic Resonance Imaging
  • Helium
  • Humans
  • Isotopes
  • Lung
  • Models, Biological
  • Numerical Analysis, Computer-Assisted
  • Pulmonary Gas Exchange

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