T1 relaxation time mapping of white matter tracts in multiple sclerosis defined by diffusion tensor imaging

Area of Science:

• Neuroimaging
• Quantitative MRI
• White Matter Disease

Background:

• T(1) relaxation time is a quantitative MRI measure for evaluating white matter disease in multiple sclerosis (MS).
• Diffusion tensor (DT) imaging defines critical white matter tracts.

Purpose of the Study:

• To investigate if T(1) mapping in specific white matter tracts can serve as a stronger surrogate marker for disability in MS.
• To compare the correlation of T(1) values in pyramidal tracts and corpus callosum with clinical disability scores.

Main Methods:

• Acquired whole brain T(1) maps and DT images from 25 MS patients and 14 healthy controls.
• Defined trajectories along pyramidal pathways and corpus callosum to sample T(1) values.
• Correlated median T(1) values with Kurtzke Functional Systems Score and Expanded Disability Status Scale.

Main Results:

• Median T(1) values were significantly longer in the pyramidal tracts, corpus callosum, and total white matter of MS patients compared to controls (p < 0.0001).
• Median pyramidal tract T(1) showed significant correlation with both the Kurtzke Functional Systems Score (r = 0.64, p = 0.0007) and the Expanded Disability Status Scale (r = 0.55, p = 0.005).
• No significant correlation was found between corpus callosum T(1) or total white matter T(1) and disability scores.

Conclusions:

• Quantifying T(1) pathology within pyramidal tracts provides a strong correlate of disability in MS, superior to global white matter burden assessment.
• Pyramidal tract T(1) may serve as an objective and sensitive measure for monitoring motor deficit progression and disability in MS.