Scan-rescan reproducibility of neurite microstructure estimates using NODDI

In this work we provide a preliminary assessment of the reproducibility of the Neurite Orientation Dispersion and Density Imaging (NODDI), a recent diffusion MRI technique for directly quantifying microstructural indices of neurites in vivo, in the human brain. It is important to assess the reproducibility of such a technique to verify the precision of the method, which has implications for translation to clinical studies. NODDI outputs indices which reflect the functional and computational complexity of various regions of the brain and thus can provide useful information, non-invasively, for understanding pathology of the brain. We compare the parameter maps derived from diffusion MRI data acquired using the NODDI protocol from a normal subject, at two separate imaging sessions. We show that the NODDI indices have reproducibility comparable to that of the DTI indices. We additionally show that the clinically feasible NODDI protocol maintains good reproducibility of parameter estimates, comparable to that of a more comprehensive protocol