Quantitative MRI Analysis of Brachial Plexus and Limb‐Girdle Muscles in Upper Extremity Onset Amyotrophic Lateral Sclerosis

Background Recent evidence highlights the potential of axonal degeneration as a biomarker for amyotrophic lateral sclerosis (ALS) detection. However, the diagnostic potential of peripheral nerve axon changes in ALS remains unclear. Purpose To evaluate the diagnostic performance of quantitative MRI of the brachial plexus and limb‐girdle muscles (LGMs) in patients with upper extremity onset of ALS. Study Type Retrospective. Population 47 patients with upper extremity onset of ALS and 20 healthy volunteers. Field Strength/Sequence 3‐T, three‐dimensional sampling perfection with application‐optimized contrasts using different flip angle evolutions with short‐tau inversion recovery sequences, T2‐weighted turbo spin‐echo Dixon sequence. Assessment The cross‐sectional area (CSA) and nerve‐muscle T2 signal intensity ratio (nT2) of the bilateral brachial plexus as well as the CSA and fat fraction (FF) of the bilateral LGMs were assessed by two radiologists. Disease severity and clinical stage of ALS patients were assessed by two neurologists. Statistical Tests Student's t‐test, Wilcoxon rank‐sum test, binary logistic regression, interclass correlation coefficient, receiver operating characteristic analysis, and correlation analysis were performed for MRI quantitative metrics and clinical variables. Significance level: P