Chu-Yu Lee1, 2, Kevin M. Bennett3, Josef P. Debbins1, 2
1Neuroimaging Research, Barrow Neurological Institute, Phoenix, AZ, United States; 2Electrical Engineering, Arizona State University, Tempe, AZ, United States; 3School of Biological and Health Systems Engineering, Arizona State University, Tempe, AZ, United States
The apparent diffusion coefficient (ADC) of the monoexponential model has been shown to decrease following ischemic stroke. The underlying mechanisms of the reduction in the ADC remain unclear. The increased cell volume fraction is suggested to be one mechanism that results in more hindered extracellular diffusion. However, the intracellular diffusion was found to decrease or increase by separate studies. Another factor of reduced membrane permeability was shown to have a minor impact on the reduced ADC. Recently, with a b-value up to 2500 s/mm2, the statistical distribution model and diffusion kurtosis model (DKI) have been used to study biophysical and pathological changes, potentially exhibiting higher sensitivity compared to the ADC. The aim of this study was to investigate the relationship between the non-monoexponential models and microstructural changes in ischemic stroke. For this purpose, we studied the fitted parameters: σ stat of the statistical distribution model (width of the distribution of diffusion rates) and Kapp of the DKI model (measure of non-Gaussian diffusion) in response to the simulated microstructural changes. We compared our simulation results to the in vivo measurements of human ischemic stroke (n = 6). The results suggest that the non-monoexponential models may be useful in identifying the biophysical mechanisms in ischemic stroke.