Selective Inversion Recovery Quantitative Magnetization Transfer Brain MRI at 7T: Clinical and Postmortem Validation...

Area of Science:

• Neuroimaging
• Biomarkers
• Multiple Sclerosis Research

Background:

• A critical need exists for imaging biomarkers to assess myelin integrity in multiple sclerosis (MS).
• Quantitative magnetization transfer imaging (qMT) using selective inversion recovery (SIR) can quantify myelin content in the brain.
• The SIR method was previously adapted for 7T MRI with a rapid turbo field echo (TFE) readout for efficient whole-brain imaging.

Purpose of the Study:

• To provide histological validation for the SIR-TFE protocol.
• To assess the in vivo feasibility and applicability of the SIR-TFE protocol in MS patients.

Main Methods:

• Performed 7T MRI scans (clinical and SIR-TFE) on a postmortem MS brain.
• Acquired in vivo SIR-TFE MRI data from 10 MS patients and 14 healthy volunteers.
• Estimated SIR parameters (PSR, R1f, kmf) and evaluated differences across tissue types (WM-Ls, NAWM, NWM) and associations with disability scores.

Main Results:

• Postmortem scans showed correspondence between histology and SIR parameters (PSR/R1f) in white matter lesions (WM-Ls) and normal-appearing white matter (NAWM).
• In vivo, significant differences in PSR, R1f, and kmf were detected between WM-Ls and normal white matter (NWM).
• Associations were found between WM-Ls/NAWM PSR and patient disability scores.

Conclusions:

• Selective inversion recovery quantitative magnetization transfer imaging (SIR-qMT) at 7T provides sensitive and quantitative measures of myelin integrity.
• The SIR-TFE protocol is suitable for both clinical and research applications in MS.