Objective: To study the rate of change of brain region diffusion tensor imaging (DTI) parameters between the right and left sides in PD patients using a longitudinal approach.

Background: Patients with Parkinson’s disease (PD) can present differentially between the right and left sides. There has been limited literature evaluating the rate of change in brain DTI parameters between sides on follow-up MRI studies.

Methods: Subjects diagnosed with PD were recruited and underwent DTI MR brain imaging at baseline and 5-6 years later using the same MR protocol. The FA and MD values in the caudate, putamen, thalamus and substantia nigra were measured on both sides by 2 independent and blinded raters. The FA, ADC and their rate of change in the ROIs in each side of the brain in all subjects were evaluated. Inter-class coefficient was determined for inter-rater variability. Statistical significance was defined at p < 0.5.

Results: A total of 46 PD patients (average age 70 years, 22 men) had 2 time-point MR scans. A significant difference in the FA value between the right and left substantia nigra at baseline (0.45 vs 0.43, p = 0.001) and the second time point (0.48 vs 0.47, p = 0.047) was found. At baseline, the FA was not significantly different between sides for the putamen (0.28 vs 0.28, p = 0.49) and thalamus (0.37 vs 0.37, p = 0.59), but became significant at the second time-point (putamen 0.36 vs 0.32, p = 0.001 and thalamus 0.39 vs 0.42, p = 0.003). There was good inter-rater reliability of > 0.80.

Conclusions: Our findings showed significant side differences in FA values in the substantia nigra, putamen and thalamus in PD. These right – left differences were more significant over time for some brain regions, suggesting that the neurodegenerative progression is asymmetric. These findings may be relevant in serial assessment of clinical disease progression in PD patients using DTI.

American Society of Neuroradiology 52nd Annual Meeting 2014.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/dti-in-parkinsons-disease-asymmetric-progression/