T1 mapping in Becker muscular dystrophy patients detects diffuse microfibrosis prior to evidence of late gadolinium enhancement or cardiac dysfunction

Background Becker muscular dystrophy (BMD) is allelic with Duchenne muscular dystrophy and represents a milder skeletal muscle phenotype; however, cardiac dysfunction remains a significant clinical problem. Cardiac involvement in BMD precedes skeletal muscular decline, and cardiomyopathy often leads to death before the age of 60 years. Cardiac magnetic resonance (CMR) is used for ventricular function assessment and myocardial tissue characterization. Late gadolinium enhancement (LGE) in BMD patients is interpreted as a sign of irreversible macrofibrosis, and often prompts changes in cardiac management to try and limit fibrosis progression. T1 mapping is a more sensitive biomarker of diffuse microfibrosis and may offer an opportunity for earlier therapeutic intervention. Currently, myocardial T1 values in BMD patients are unknown. The purpose of this study is to measure T1 values in BMD patients to determine the prevalence of diffuse myocardial microfibrosis, and its relation to LGE and cardiac dysfunction.