Kadir Şimşek1, André Döring1,2, André Pampel3, Harald E. Möller3, and Roland Kreis1
1Department of Radiology and Biomedical Research, University of Bern, Bern, Switzerland, 2Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, Cardiff University, Cardiff, United Kingdom, 3Max-Planck Institution for Human Cognitive and Brain Sciences, Leipzig, Germany
1Department of Radiology and Biomedical Research, University of Bern, Bern, Switzerland, 2Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, Cardiff University, Cardiff, United Kingdom, 3Max-Planck Institution for Human Cognitive and Brain Sciences, Leipzig, Germany
Diffusion-weighted
MRS is used at short-TE in human brain with two motion compensation methods and
a novel simultaneous spectral/diffusion-decay model to study non-Gaussian
diffusivity of metabolites at high b-values and to determine the macromolecular
background spectrum by diffusion.
Fig.3: Fitted
diffusion decays as obtained with the different approaches described in the
text. Free-Fit data was modeled as mono- and biexponential decay. Biexp-Fit
(blue) is consistent for some metabolites but shows diverging results for
others. The non-Gaussian nature of diffusion is evident in both approaches for most
metabolites. At the bottom, spectra with the fits from Free-Fit as well as
Biexp-Fit are shown documenting how small the differences are even though the
decay function seem to differ substantially for some metabolites. (blue: Biexp-Fit;
red; Free-Fit)
Fig. 1: Illustration
to motivate the need for the MM peak-based signal correction. For multiple
subjects, the peak areas of MM0.9 are plotted in relation to the monoexponential
decay fit for the cohort data from subjects without apparent strong artifactual
signal decay. Subject 2 shows systematic additional signal decay with higher
b-values on top of the MM diffusion effect, while subjects 1 and 3 show strong random
fluctuations.
