P.330Fibroadipose Infiltration Scores of Specific Muscles Are Influenced by Disease Duration in Partial Merosin Deficiency

Muscle MRI pattern in laminin alpha2 (merosin) deficient muscular dystrophy is not well known. Particularly, changes in imaging phenotype along disease evolution are poorly understood. Our aim is to identify muscles and regions with higher correlation between fibroadipous infiltration and disease duration in a cohort of patients with partial merosin deficient muscular dystrophy. Whole body and lower limb muscle MRI were collected from 17 patients (median disease duration = 24.50 years, range = 3.25-60.75) with genetic confirmed diagnosis of merosin deficient muscular dystrophy and partial deficiency at muscle biopsy. An experienced radiologist systematically scored 55 muscles following Lamminen modified scoring system for fibroadipose infiltration. Partial Spearman's rho correlation coefficient between fibroadipose score and disease duration (considering disease onset) was calculated for every muscle. The muscles showing more relationship between fibroadipose scores and with disease duration were long head of biceps femoris (partial rho = 0.900, CI95%: 0.662-0.964), vastus lateralis (partial rho = 0.890, CI95% 0.577-0.975), tensor fascia latae (partial rho = 0.868, CI95% 0.615-0.950), latissimus dorsi (partial rho = 0.861, CI95% 0.623-0.964) and sartorius (partial rho = 0.850, CI95% 0.713-0.952). When comparing different regions of the body, the thigh showed th highest correlation between muscle infiltration and disease duration. We identified several muscles, most localized in the thigh, that are highly correlated with disease duration in patients with partial merosin deficient muscular dystrophy. Quantitative MRI targeting to those muscles might be used as a biomarker to monitor the course of the disease as changes in these muscles reflect the long-term progression of the disorder.