Olfactory Impairment in Parkinson's Disease Studied with Diffusion Tensor and Magnetization Transfer Imaging

Area of Science:

• Neuroimaging
• Neurology
• Biomedical Engineering

Background:

• Olfactory impairment is a common early symptom of Parkinson's disease (PD).
• Microstructural changes in cerebral white matter can be detected noninvasively using Diffusion Tensor Imaging (DTI) and Magnetization Transfer (MT).

Purpose of the Study:

• To investigate white matter alterations linked to olfactory impairment in Parkinson's disease.
• To compare the efficacy of DTI and MT imaging in detecting these neuroanatomical changes.

Main Methods:

• 22 PD patients and 13 healthy controls underwent DTI, MT, and olfactory discrimination testing.
• Tract-Based Spatial Statistics (TBSS) and Region of Interest (ROI) analyses were applied to DTI data.
• Voxelwise and ROI analyses were performed on MT data, focusing on olfactory-related white matter regions.

Main Results:

• DTI revealed decreased axial diffusivity in the left uncinate fasciculus and white matter near the left olfactory sulcus in PD patients.
• ROI analysis of DTI showed reduced axial diffusivity in the right orbitofrontal cortex and left entorhinal cortex white matter.
• No significant differences in fractional anisotropy, radial diffusivity, or MT were found between groups.

Conclusions:

• Region of Interest analysis using DTI can identify microstructural white matter changes adjacent to olfactory areas in Parkinson's disease.
• Magnetization Transfer imaging was less sensitive than DTI in detecting these specific white matter alterations associated with PD.