Comparative study of diffusion kurtosis imaging in deep brain nucleus in different subtypes of Parkinson′s disease

Abstract

Objective To compare the difference in the microstructure of gray matter nucleus in basal ganglia of different movement subtypes of Parkinson′s disease (PD) by diffusion kurtosis imaging (DKI) technique, and to analyze its clinical significance in the process of disease occurrence and development. Methods A total of 44 PD patients and 20 healthy controls (HC) admitted to the First Hospital of Shanxi Medical University from July 2017 to October 2018 were recruited into the study. The PD patients were classified into tremor dominant (TD) and non-tremor dominant (NTD) subtypes according to motor symptoms. All participants were scanned for DKI sequence. Fractional anisotropy (FA), mean kurtosis (MK), and mean diffusivity (MD) were obtained from bilateral red nucleus, substantia nigra, caudate nucleus, globus pallidus, putamen, and thalamus. The DKI of the deep brain nucleus in TD, NTD, HC groups was compared, and relationships between DKI and clinical measures were tested. Results Comparing the two substypes of PD with the HC group, the TD group had lower FA value (0.346±0.006 vs 0.389±0.009, U=-3.052, P=0.007), higher MK value (1.101±0.008 vs 0.981±0.006, U=-5.577, P=0.000) and higher MD value (1.005 (0.919, 1.082) vs 0.934 (0.899, 0.970), U=2.493, P=0.038) in the substantia nigra ipsilateral to the more affected side than the HC group. The NTD group had higher MK value in the bilateral substantia nigra than the HC group (less affected side: 1.090±0.022 vs 0.990±0.008, U=-4.102, P=0.000; more affected side: 1.071±0.020 vs 0.981±0.006, U=-3.728, P=0.001). In the PD patients, the MK value in the substantia nigra ipsilateral to the more affected side showed a negative correlation with the Hoehn-Yahr (H-Y) grade, Unified Parkinson′s Disease Rating Scale (UPDRS) Ⅲ scores, and non-tremor scores (r=-0.299, P=0.048; r=-0.366, P=0.015; r=-0.402, P=0.007). The FA values of the bilateral putamen of the TD group and the NTD group were lower than those of the HC group. The FA value in putamen contralateral to the more affected side was positively correlated with H-Y grade, UPDRS Ⅲ scores, and non-tremor scores (r=0.331, P=0.028; r=0.403, P=0.007; r=0.376, P=0.012). Compared with the HC group, the FA value of the bilateral globus pallidus was lower in the TD group. Comparing different subtypes of PD, only the FA and MK values of the bilateral thalamus were different. The tremor scores of PD patients were negatively correlated with the FA value of bilateral thalamus (less affected side: r=-0.371, P=0.013; more affected side: r=-0.402, P=0.007), and positively correlated with MK value (less affected side: r=0.547, P<0.01; more affected side: r=0.532, P<0.01). Conclusions The microstructure of the deep brain nucleus of PD is changed, while the TD and NTD patients have only differences in the microstructure changes of the thalamus. The changes in the microstructure of the thalamus are related to the severity of tremor in PD patients. Key words: Parkinson disease; Tremor; Magnetic resonance imaging; Diffusion kurtosis imaging