The magnetic resonance imaging spectrum of facioscapulohumeral muscular dystrophy.

INTRODUCTION: Facioscapulohumeral muscular dystrophy (FSHD) is associated with a repeat contraction in the D4Z4 gene locus on chromosome 4q35. We used a one-step quantitative magnetic resonance imaging (MRI) method to evaluate muscle, edema, and fat in patients spanning the range of severity.

METHODS: Fifteen patients with FSHD were compared with 10 healthy subjects using non-negative linear least-squares fitting of 32-echo relaxation data (T2). The results were compared with a biexponential approach for characterizing muscle/fat ratio and T2 relaxation measurements from fat-suppressed inversion recovery.

RESULTS: Increased T2 signal consistent with edema was common in FSHD subjects, a pattern not present in healthy controls. A varied pattern of edema and fatty replacement in muscles was shown.

CONCLUSIONS: As a discrete biomarker, edema may be useful for following the clinical course of FSHD. Future work toward optimizing measurement is discussed.