CHU-YU LEE1, Kevin M. Bennett2, Lina J. Karam1, Joseph P. Debbins3
1Department of Electrical Engineering, Arizona State University, Tempe, AZ, USA; 2Harrington Department of Bioengineering, Arizona State University, Tempe, AZ, USA; 3Keller Center for Imaging Innovation, Barrow Neurological Institute, Phoenix, AZ, USA
Sretched exponential (\DWI) and second-order cumulant (DKI) models were developed to describe the non-monoexponential signal attenuation of a DWI experiment. Both \ and Kapp are thought to reflect heterogeneity in water diffusion rates, but their relationship to the underlying biophysics is still unclear. In this work, we simulated a simplified physical system of either one or two water compartments with a known distribution of water diffusion rates, and studied how these two models behaved. Our results showed that \ is directly related to var[D] in both the one- and two-compartment models. Kapp is sensitive to both to E[D] and var[D]. Besides, \DWI may be preferred when high b-values can be used, but DKI may be preferred at low b-values. However, because DKI is limited to low b-value ranges, it may be insensitive to changes in slow diffusion. These two models are thus similar, but have separate relationships to the intravoxel distribution of water diffusion rates.
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