Background: Preliminary work has shown that diffusion tensor MR imaging (DTI) may contribute to the diagnosis of Parkinson’s disease (PD).
Objectives: We conducted a large prospective case-control study to determine (1) if fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values on MR diffusion tensor imaging (DTI) in the basal ganglia and substantia nigra are different between Parkinson’s Disease (PD) and healthy controls, and (2) the predictive value of these parameters and their clinical utility.
Methods: DTI imaging was carried out in PD and controls. The FA and ADC values were obtained from various brain structures on the DTI scan using the Diffusion Tensor Taskcard. The structures studied were: caudate, putamen, globus pallidus, thalamus and substantia nigra.
Results: A total of 151 subjects comprising of 73 PD patients (41 men, 32 women; mean age, 63.6 years) and 78 age-and sex-matched control subjects were studied. The FA value of the substantia nigra in PD patients was lower compared to controls (0.403, versus 0.415, P = .001). However, no significant differences were demonstrated for the FA or ADC values of the other structures. Multiple regression analysis revealed that the clinical severity of PD correlated inversely with the FA value in the substantia nigra in PD patients (regression coefficient = -0.019). No single FA value possessed both a high positive and negative predictive power for PD.
Conclusions: We demonstrated in a large prospective case-control study that the FA value in the substantia nigra on DTI was lower in PD compared to healthy controls, and correlated inversely with the clinical severity of PD. Further longitudinal studies would be helpful to assess the clinical utility of serial FA measurement of the substantia nigra in objective quantification of disease progression and monitoring of therapeutic response.
- parkinson's disease