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Träfflista för sökning "WFRF:(Parker Geoff A.) ;lar1:(lu)"

Sökning: WFRF:(Parker Geoff A.) > Lunds universitet

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1.
  • Kerkelä, Leevi, et al. (författare)
  • Comparative analysis of signal models for microscopic fractional anisotropy estimation using q-space trajectory encoding
  • 2021
  • Ingår i: NeuroImage. - : Elsevier BV. - 1053-8119. ; 242
  • Tidskriftsartikel (refereegranskat)abstract
    • Microscopic diffusion anisotropy imaging using diffusion-weighted MRI and multidimensional diffusion encoding is a promising method for quantifying clinically and scientifically relevant microstructural properties of neural tissue. Several methods for estimating microscopic fractional anisotropy (µFA), a normalized measure of microscopic diffusion anisotropy, have been introduced but the differences between the methods have received little attention thus far. In this study, the accuracy and precision of µFA estimation using q-space trajectory encoding and different signal models were assessed using imaging experiments and simulations. Three healthy volunteers and a microfibre phantom were imaged with five non-zero b-values and gradient waveforms encoding linear and spherical b-tensors. Since the ground-truth µFA was unknown in the imaging experiments, Monte Carlo random walk simulations were performed using axon-mimicking fibres for which the ground truth was known. Furthermore, parameter bias due to time-dependent diffusion was quantified by repeating the simulations with tuned waveforms, which have similar power spectra, and with triple diffusion encoding, which, unlike q-space trajectory encoding, is not based on the assumption of time-independent diffusion. The truncated cumulant expansion of the powder-averaged signal, gamma-distributed diffusivities assumption, and q-space trajectory imaging, a generalization of the truncated cumulant expansion to individual signals, were used to estimate µFA. The gamma-distributed diffusivities assumption consistently resulted in greater µFA values than the second order cumulant expansion, 0.1 greater when averaged over the whole brain. In the simulations, the generalized cumulant expansion provided the most accurate estimates. Importantly, although time-dependent diffusion caused significant overestimation of µFA using all the studied methods, the simulations suggest that the resulting bias in µFA is less than 0.1 in human white matter.
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2.
  • Levine, Hagai, et al. (författare)
  • Male reproductive health statement (XIIIth international symposium on Spermatology, may 9th-12th 2018, Stockholm, Sweden
  • 2018
  • Ingår i: Basic and Clinical Andrology. - : Springer Science and Business Media LLC. - 2051-4190. ; 28:1
  • Tidskriftsartikel (refereegranskat)abstract
    • On the occasion of the XIIIth International Symposium on Spermatology held from 9 to 13 May 2018 in Stockholm (Sweden), participants (guest speakers and audience) collectively felt the need to make a public statement on the general issue of male reproductive health. Our intention is to raise awareness of what we believe is a neglected area of research despite alarming situations around the world. The disclosure strategy desired by the co-authors is to bring it to the attention of the greatest number partly by considering co-publication in the various periodicals dealing with Reproductive Biology and Andrology. BaCA's editorial office accepted this mission and found it natural that our periodical, the official journal of the French Andrology Society (SALF), should carry this message.
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3.
  • Morgan, Alexandra R, et al. (författare)
  • Feasibility assessment of using oxygen-enhanced magnetic resonance imaging for evaluating the effect of pharmacological treatment in COPD.
  • 2014
  • Ingår i: European Journal of Radiology. - : Elsevier BV. - 1872-7727 .- 0720-048X. ; 83:11, s. 2093-2101
  • Tidskriftsartikel (refereegranskat)abstract
    • Oxygen-enhanced MRI (OE-MRI) biomarkers have potential value in assessment of COPD, but need further evaluation before treatment-induced changes can be interpreted. The objective was to evaluate how OE-MRI parameters of regional ventilation and oxygen uptake respond to standard pharmacological interventions in COPD, and how the response compares to that of gold standard pulmonary function tests.
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