Asymmetrical diffusion tensor imaging indices of the rostral substantia nigra in Parkinson's disease.
OBJECTIVE
Motor asymmetry in Parkinson's disease (PD) is evident clinically and on functional neuroimaging, but not reported in diffusion tensor imaging (DTI). We aim to determine if asymmetry in fractional anisotropy (FA) and apparent diffusion coefficient (ADC) can be detected in the substantia nigra (SN) of PD subjects.


METHODS
DTI scans were performed on 11 PD and 12 healthy subjects. Regions of interest (ROIs) were drawn by 2 independent raters at the caudal, middle and rostral SN on each side. FA and ADC were extracted from the ROIs.


RESULTS
Significant asymmetry was observed in the FA (p < 0.005) and ADC (p < 0.00005) at the rostral SN of PD subjects. The differences in FA and ADC across the left and right rostral SN were significantly different between PD and healthy subjects, p < 0.05 and p < 0.02 respectively. PD subjects had significantly higher ADC at the left rostral SN than healthy subjects (p < 0.01). Significant correlation between the Unified Parkinson's Disease Rating Scale (UPDRS) motor scores and the FA was noted in the left rostral SN (r = 0.7, p < 0.03).


CONCLUSIONS
Asymmetry in DTI indices was noted at the rostral SN of PD subjects. The relationship between FA in the SN and UPDRS motor score was studied. Our findings may provide a model for better understanding of the implication of FA reduction in the SN.
Department of Neurology, National Neuroscience Institute, Singapore.
Bhaskaran David
BD
Prakash
Yih-Yian
YY
Sitoh
Louis C S
LC
Tan
Wing Lok
WL
Au
D000368:Aged; D016880:Anisotropy; D056324:Diffusion Tensor Imaging; D004185:Disability Evaluation; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000473:pathology* / Q000503:physiopathology; D012720:Severity of Illness Index; D013223:Statistics as Topic; D013378:Substantia Nigra / Q000473:pathology*