Diffusion kurtosis imaging (DKI) by measuring non-Gaussian diffusion allows an accurate estimation of the distribution of water molecule displacement and may correctly characterize microstructural brain changes caused by neurodegeneration. The aim of this study was to evaluate the ability of DKI to detect changes induced by a-synuclein (a-syn) accumulation in a-syn over-expressing transgenic mice (TNWT-61) in both gray matter (GM) and white matter (WM) using region of interest (ROI) and tract-based spatial statistics analyses, respectively, and to explore the relationship between a-syn accumulation and DKI metrics in our regions of interest. Fourteen-month-old TNWT-61 mice and wild-type (WT) littermates underwent in vivo DKI scanning using the Bruker Avance 9.4 Tesla magnetic resonance imaging system. ROI analysis in the GM regions substantia nigra, striatum, hippocampus, sensorimotor cortex, and thalamus and tractbased spatial statistics analysis in WM were performed. Immunohistochemistry for a-syn was performed in TNWT-61 mice and correlated with DKI findings. We found increased kurtosis and decreased diffusivity values in GM regions such as the thalamus and sensorimotor cortex, and in WM regions such as the external and internal capsule, mamillothalamic tract, anterior commissure, cingulum, and corpus callosum in TNWT-61 mice as compared to WT mice. Furthermore, we report for the first time that a-syn accumulation is positively Received October 3, 2015; revised manuscript received November 9, 2015; accepted December 10, 2015.Address correspondence and reprint requests to Prof. Irena Rektorova, Applied Neuroscience Research Group, CEITEC Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic. E-mail: irena.rektorova@ ceitec.muni.czAbbreviations used: AD, axial diffusivity; AK, axial kurtosis; DKI, diffusion kurtosis imaging; DTI, diffusion tensor imaging; FA, fractional anisotropy; FLASH, fast low angle shot; FOV, field of view; GM, gray matter; GRAPPA, generalized auto-calibrating partially parallel acquisitions; MD, mean diffusivity; MK, mean kurtosis; MRI, magnetic resonance imaging; PD, Parkinson's disease; PET, positron emission tomography; RD, radial diffusivity; RK, radial kurtosis; ROI, region of interest; SE-EPI, spin-echo echo-planar-imaging; SN, substantia nigra; SPECT, single photon emission computed tomography; TBSS, tractbased spatial statistics; TNWT-61, transgenic mice over-expressing asyn; TR, repetition time; WM, white matter; a-syn, a-synuclein. correlated with kurtosis and negatively correlated with diffusivity in the thalamus. The study provides evidence of an association between the amount of a-syn and the magnitude of DKI metric changes in the ROIs, with the potential of improving the clinical diagnosis of Parkinson's disease.