Muscle MRI quantifies disease progression in amyotrophic lateral sclerosis.

BACKGROUND AND OBJECTIVES

Quantitative and operator-independent biomarkers of disease progression are urgently needed in amyotrophic lateral sclerosis (ALS) research. We assess the potential of skeletal muscle MRI as a sensitive and reliable outcome measure for future ALS clinical trials.

METHODS

In this longitudinal cohort study, muscle MRI of head-neck, upper and lower limb regions, alongside clinical and functional assessments, were acquired at three time points over the individual maximum observation period (iMOP) of 1 year in 20 patients with ALS and 16 healthy controls. Quantitative MRI parameters cross-sectional area (CSA), volume (VOL), fat fraction, functional rest muscle area and water T2 (T) were correlated with changes in clinical disease severity (functional rating scales and myometry).

RESULTS

Among 20 patients with ALS, 17 completed follow-up. Progressive muscle atrophy (CSA, VOL) was observed at hand (rs=0.66), head-neck (partial η²=0.47) and lower-limb level (thighs: η²=0.56, calves: η²=0.54) over iMOP. MRI changes correlated with leg muscle strength (knee extension: r=0.77; plantar flexion: r=0.78), hand grip strength (r=0.71) and functional rating scales (r=0.68).

INTERPRETATION

Our findings demonstrate the effectiveness of muscle MRI as a sensitive neuroimaging biomarker of disease progression in ALS, highlighting its potential application in clinical trials.