This thesis examines structural and functional abnormalities of extraocular muscles in myasthenia gravis using quantitative MRI. Advanced imaging approaches are used to characterize muscle composition, contractile behavior, and fatigue-related functional impairment. The findings identify disease-associated imaging signatures that correlate with clinical manifestations such as ptosis and ophthalmoparesis. The work proposes MRI-derived biomarkers to improve diagnosis, phenotyping, and longitudinal monitoring in neuromuscular ophthalmology.