T₁ /T₂ ratio from 3T MRI improves multiple sclerosis cortical lesion contrast

Area of Science:

• Neuroimaging
• Radiology
• Neurology

Background:

• Cortical demyelinated lesions are common in multiple sclerosis (MS) and linked to disability.
• Current sensitive MRI methods for cortical lesions are not routinely available.
• There is a need for accessible MRI techniques for cortical lesion detection.

Purpose of the Study:

• To evaluate the sensitivity of the T1-weighted/T2-weighted (T1/T2) signal intensity ratio for detecting focal cortical lesions.
• To compare the T1/T2 ratio's sensitivity with other high-field MRI methods.

Main Methods:

• Analyzed 3-Tesla (3T) and 7-Tesla (7T) MRI data from 10 MS patients.
• Calculated T1/T2 images by dividing 3T T1-weighted (T1w) by 3T T2-weighted (T2w) fluid-attenuated inversion recovery images.
• Assessed 614 cortical lesions identified on 7T images using registered 3T sequences, including T1/T2, T1w, T2w, and IR-SWIET.

Main Results:

• T1/T2 images showed significantly higher contrast between lesional and non-lesional cortical signal intensity (median ratio 1.29) compared to T1w (1.01), T2w (1.17), and IR-SWIET (1.21).
• The observed differences were statistically significant (p < .002 for T1w and T2w, p < .03 for IR-SWIET).

Conclusions:

• T1/T2 ratio imaging is sensitive for detecting cortical lesions in MS.
• Incorporating T1/T2 ratio analysis can improve the accessibility of cortical lesion detection in both research and clinical settings.