Dissociated Magnetic Susceptibility and White Matter Microstructure in Type 2 Diabetes with Peripheral Neuropathy

Area of Science:

• Neuroimaging
• Neurology
• Diabetology

Background:

• Diabetic peripheral neuropathy (DPN) is associated with brain structural changes.
• Type 2 diabetes mellitus (T2DM) patients exhibit varying degrees of neuropathy.
• Understanding brain alterations in T2DM with and without DPN is crucial.

Purpose of the Study:

• To compare white matter microstructural and iron-related alterations in T2DM patients with and without DPN.
• To investigate the sensitivity of quantitative susceptibility mapping (QSM) for DPN detection.
• To identify potential neuroimaging markers for DPN.

Main Methods:

• Recruited participants: T2DM (n=26), DPN (n=42), and healthy controls (HCs, n=37).
• Utilized diffusion tensor imaging (DTI) for white matter microstructure and QSM for iron-related alterations.
• Performed neuropsychological assessments, electromyography, and statistical analyses including ROC curve analysis.

Main Results:

• DPN group showed elevated mean and axial diffusivity in specific white matter tracts compared to T2DM.
• Significant increases in magnetic susceptibility values (MSV) were observed in the cerebellum and thalamus (pulvinaris superficialis, lamella medialis interpolaris) in the DPN group.
• Cerebellar MSV correlated with fasting blood glucose, and thalamic MSV correlated with lipid profiles in DPN patients. A fusion model achieved high diagnostic efficacy (AUC=0.888).

Conclusions:

• DPN exhibits a dissociation between subtle DTI changes and more pronounced QSM abnormalities in the thalamic-cerebellar circuit.
• Iron-related alterations detected by QSM in this pathway are potentially more sensitive indicators for DPN than DTI.
• QSM-based iron alterations may serve as a valuable imaging biomarker for DPN.