Aβ	Amyloid-β
AD	Axial diffusivity
ADT	Free water-corrected axial diffusivity
AK	Axial kurtosis
ALS	Amyotrophic lateral sclerosis
ALSFRS-R	Amyotrophic lateral sclerosis functional rating scale-revised
AlzD	Alzheimer’s disease
APOE	Apolipoprotein E
AUC	Area under the receiver-operating characteristics curve
C9ORF72	Chromosome 9 open reading frame 72 gene
COV	Coefficient of variation
CSF	Cerebrospinal fluid
DKI	Diffusion kurtosis imaging
DTI	Diffusion tensor imaging
FA	Fractional anisotropy
FAT	Free water-corrected fractional anisotropy
FWI	Free-water imaging
GM	Gray matter
GBSS	Gray matter-based spatial statistics
ICVF	Intracellular volume fraction
ISOVF	Isotropic volume fraction
MCI	Mild cognitive impairment
MD	Mean diffusivity
MDT	Free water-corrected mean diffusivity
MK	Mean kurtosis
MMSE	Mini-mental state examination
MRI	Magnetic resonance imaging
MSA	Multiple system atrophy
NODDI	Neurite orientation dispersion and density imaging
ODI	Orientation dispersion index
PD	Parkinson’s disease
PET	Positron emission tomography
PSP	Progressive supranuclear palsy
RD	Radial diffusivity
RDT	Free water-corrected radial diffusivity
RK	Radial kurtosis
ROC	Receiver-operating characteristics
ROI	Region of interest
SN	Substantia nigra
TBSS	Tract-based spatial statistics
WM	White matter
UPDRS	Unified Parkinson’s disease rating scale