Chronic T2 Lesions in Multiple Sclerosis are Heterogeneous Regarding Phase MR Imaging

Area of Science:

• Neuroimaging
• Radiology
• Neurology

Background:

• Multiple Sclerosis (MS) is a demyelinating disease characterized by white matter lesions.
• Understanding the heterogeneity of MS lesions is crucial for diagnosis and treatment.
• Current imaging techniques provide limited information on lesion pathology.

Purpose of the Study:

• To investigate the utility of phase imaging in characterizing MS lesions.
• To explore the combination of phase imaging with mean diffusivity (MD) and magnetization transfer ratio (MTR) for differentiating MS lesion heterogeneity.
• To determine if phase characteristics are independent of MTR and MD in chronic T2 lesions.

Main Methods:

• Magnetic Resonance Imaging (MRI) including diffusion tensor imaging (DTI), magnetization transfer imaging (MTI), and susceptibility-weighted imaging (SWI) was performed on 23 MS patients.
• Mean values for MTR, MD, and filtered phase were extracted from 138 chronic MS lesions and normal-appearing white matter (NAWM).
• Correlations between imaging parameters were examined, and a hierarchical clustering algorithm was applied to lesion groups.

Main Results:

• Phase characteristics were found to be independent of MTR and MD in chronic T2 lesions.
• Cluster analysis identified five distinct lesion groups based on MTR, MD, and phase values.
• Lesion groups with increased phase values showed moderate MD increase and MTR decrease, while groups near NAWM exhibited varying degrees of MD increase and MTR decrease.

Conclusions:

• Increased phase is primarily observed in MS lesions with significant MTR decrease and moderate MD increase.
• Phase imaging appears to be an independent parameter for characterizing MS lesions.
• Phase imaging provides valuable additional information for understanding MS lesion heterogeneity.