Longitudinal Quantitative MRI Provides Responsive Outcome Measures for Early and Late Muscle Changes in ALS

Area of Science:

• Neurology
• Radiology
• Biomedical Engineering

Background:

• Muscle magnetic resonance imaging (MRI) shows promise for monitoring Amyotrophic Lateral Sclerosis (ALS) progression.
• The responsiveness and clinical utility of quantitative muscle MRI in ALS trials are not well-established.

Purpose of the Study:

• To evaluate the responsiveness of quantitative muscle MRI measures for assessing disease progression in ALS patients.
• To compare the sensitivity of MRI-derived metrics against established clinical assessments in an ALS clinical trial.

Main Methods:

• Longitudinal quantitative muscle MRIs (fat fraction, T2, CSA, RMA) were performed on ALS participants over 12 months.
• Non-MRI measures included muscle strength (ATLIS) and the ALSFRS-R scale.
• Standardized Response Means (SRMs) were calculated to assess measure responsiveness.

Main Results:

• Significant changes in muscle fat fraction, CSA, and RMA were detected as early as 1 month.
• Muscle fat fraction and T2 showed high responsiveness at 6 months, outperforming ALSFRS-R.
• MRI measures demonstrated varying correlations with muscle strength and ALSFRS-R leg subscores.

Conclusions:

• Quantitative muscle MRI exhibits high responsiveness and low variability, making it a valuable outcome measure for ALS clinical trials.
• Muscle MRI serves as a novel and complementary tool for tracking disease progression in ALS.