Quantification of non-Gaussian diffusion in the human heart in vivo

Motivation: Diffusion tensor modeling, which is based on Gaussian diffusion, is commonly used in cardiac diffusion MRI (dMRI). However, the tissue's microstructure (cells, membranes, etc.) restricts the water molecules and deviates the signal from Gaussian behavior. Goal(s): This effect may be observed for higher b-values, which are presently outside the realm of routine cardiac dMRI due to the limited gradient strength of clinical scanners. Approach: Cardiac-gated, second-order motion-compensated dMRI were performed with $$$\mathrm{b_{max}=1500\,s/mm^2}$$$ in healthy volunteers on a 3T MRI scanner with $$$\mathrm{G_{max}=300\,mT/m}$$$. Results: We demonstrate deviation of the signal from Gaussian decay at $$$\mathrm{b>500\,s/mm^2}$$$ confirming the presence of non-Gaussian diffusion at higher b-values. Impact: This work demonstrates feasibility of quantifying non-Gaussian diffusion in the human heart in vivo $$$\mathrm{\textbf{at realistic echo times}}$$$, using Connectom scanner ($$$\mathrm{G_{max}=300\,mT/m}$$$, 4-8 times stronger than clinical scanners). It may open the field for new biomarkers in cardiac diffusion MRI.