Normal appearing and diffusely abnormal white matter in patients with multiple sclerosis assessed with quantitative...

Area of Science:

• Neuroimaging
• Quantitative Magnetic Resonance Imaging (qMRI)
• Quantitative Magnetic Resonance Spectroscopy (qMRS)

Background:

• Magnetic Resonance Imaging (MRI) detects white matter (WM) lesions in MS but shows low correlation with clinical disability.
• Investigating changes in normal-appearing white matter (NAWM) and diffusely abnormal white matter (DAWM) is crucial for understanding MS progression.
• Quantitative MRI (qMRI) and MRS (qMRS) techniques aim to detect and quantify these subtle WM changes.

Purpose of the Study:

• To investigate NAWM and DAWM using qMRI and qMRS in MS patients with typical and atypical lesion loads.
• To compare qMRI/qMRS findings in MS patients with normal white matter (NWM) in healthy controls.
• To explore correlations between qMRI measurements, clinical parameters, and metabolite concentrations.

Main Methods:

• QMRI and qMRS measurements were conducted on a 1.5 T MR scanner.
• 35 MS patients (20 MRI-positive, 15 MRI-negative) and 20 healthy controls were included.
• QMRI properties and metabolite concentrations were analyzed in regions of interest (ROIs) of NAWM, DAWM, and NWM.

Main Results:

• NAWM differed significantly between MRI-negative MS patients, MRI-positive MS patients, and controls.
• R1 and R2 of NAWM in MRI-positive patients correlated negatively with EDSS and MSSS scores.
• DAWM differed from NWM, with R2 of DAWM associated with brain parenchyma fraction (BPF).

Conclusions:

• NAWM and DAWM represent independent pathological entities in MS.
• The observed correlations between qMRI and clinical status may help explain the clinicoradiological paradox in MS.
• qMRI and qMRS provide valuable insights into white matter changes beyond focal lesions in MS.