Objective: Brain microstructure alteration using MRI in Parkinson’s disease (PD) have not been well studied. We analysis the white matter alterations in Parkinson’s disease with levodopa induced dyskinesia (LID) using neurite orientation dispersion and density imaging (NODDI).

Background: NODDI is an imaging method of MRI that applies a model for orientation dispersion index (ODI), intracellular volume fraction (ICVF) and isotropic volume fraction (ISO) to diffusion weighted image using the 2-shell protocol [1]. Levodopa induced dyskinesia (LID) is known as the one of motor complications in advanced Parkinson’s disease (PD). LID might be associated with synaptic plasticity in cortico-striatal-thalamic loop due to induced chronic levodopa treatment. Previous studies reported enlargement of dendrite spine head or decreased spine density in caudate-putamen, nucleus accumbens and primary motor cortex in PD animal model [2].

Method: We enrolled participants of healthy controls and clinically established PD with permission, and imaged using 3-tesla MR scanner. We excluded different diagnosed like multiple system atrophy, and cognitive impairment participants (MMSE <24 points). MRI methods were taking diffusion tensor imaging (DTI), diffusion kurtosis imaging (DKI) and NODDI.

Results: We analyses age and gender matched 23 controls, 27 PD patients without LID (without-LID) and 25 PD patients with LID (with-LID). In back ground of participants, with-LID and without-LID was not significant difference in age, gender, MDS-UPDRS part 1 and 3 score, but was significantly difference in disease duration and levodopa equivalent dose. MRI revealed higher in ICVF and ODI on NODDI were significant difference in with-LID compared with without-LID. These parameters are not significant between controls and with-LID.

Conclusion: PD with-LID patients were significant difference white matter structure compared with without-LID. Higher ICVF and ODI represent the higher axon and dendrite density or dispersion. These findings indicate that white matter microstructures might be more preserved in with-LID patients similar as healthy controls than without-LID.

References: [1] Zhang H, et al. Neuroimage. 2012 Jul 16;61(4):1000-1016. [2] Nishijima H, et al. Mov Disord. 2018 Jul;33(6):877-888.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/preserved-white-matter-microstructure-in-parkinsons-disease-patients-with-levodopa-induced-dyskinesia-evaluation-by-neurite-orientation-dispersion-and-density-imaging-noddi/