Abstract 17186: Regional Extracellular Volume Fraction Can Identify Cardiac Muscle Changes in Patients With Duchenne Muscular Dystrophy

Abstract

Background: Duchenne muscular dystrophy (DMD) is an X-linked inherited disorder causing dilated cardiomyopathy with variable onset and progression. Our aim was to compare native T1 mapping and extracellular volume fraction (ECV) in boys with DMD to controls to identify markers of preclinical myocardial disease. Methods: With IRB approval and informed consent/assent, 17 boys with DMD had cardiac magnetic resonance imaging (MRI) with contrast. Ejection fraction (EF), presence of late gadolinium enhancement (LGE), native T1, and ECV mapping were obtained using a modified Look-Locker sequence on a 1.5T MR scanner (Figure 1). Results were compared with age and gender matched controls with no history predisposing to cardiac fibrosis (i.e. bypass, myocarditis, etc). Results: Seventeen DMD subjects (age 14 ± 5 years; EF 56% ± 8%) were compared with 13 normal controls (age 17 ± 4 years) with normal EF and no LGE. DMD subjects had low-normal EF (average EF 56% ± 8%) and 10 of 17 (59%) had evidence of LGE, all in the lateral location. Comparing native T1 in DMD vs controls, septal native T1 was 1060 ± 71 ms versus 990 ± 34 ms (p < 0.01) and lateral native T1 was 1090 ± 93 versus 978 ± 37 ms, respectively (p < 0.01). Comparing ECV values in DMD vs controls, septal ECV was 29.6 ± 7.8 and 25.9 ± 3.4 (p = 0.03) and lateral ECV was 32.7 ± 8.7 and 24.4 ±3.6 (p < 0.01), respectively. All DMD patients with abnormal EF and/or presence of LGE also had higher ECV values. Conclusions: ECV is strongly-related to DMD and differs significantly compared to normals, particularly in the lateral wall. ECV mapping may be a useful technique for identifying preclinical myocardial changes in DMD. Figure 1. A) Precontrast T1 map, B) post contrast T1 map and C) ECV map with scale on the right in the short axis projection of a boy with Duchenne muscular dystrophy. Arrows indicate elevated values laterally.