Investigation of the dependence of free water and pseudo-diffusion MRI estimates on the cardiac cycle

With diffusion MRI (dMRI) data at multiple diffusion weightings it is possible to quantify the relative fractions of multiple water pools. In this work, we investigated changes in free water diffusion and micro- and macro-vascular pseudo-diffusion during the cardiac cycle. Further, we propose a data driven method to bin the dMRI signals according to the cardiac phase. dMRI at 4 diffusion weightings was acquired 80 times with short repetition time. A multi-exponential fit of the binned data showed increases of free water in white matter and periventricular areas, and opposite increases/decreases for micro- and macro-vascular pseudo-diffusion in grey matter, respectively.