A comparison five years apart of ultrasound and MRI scans of five leg muscles from 20 people with facioscapulohumeral muscular dystrophy (FSHD), aged between 35 and 77, showed that:
- 95% had FSHD type 1, one person had FSHD type 2;
- 90% of patients were symptomatic;
- 17% of initially normal muscles had an increase in their echogenicity z-score (EZ-score) ≥ 1 and 7% an increase of more than 10% in the fat fraction on MRI;
- muscles that initially had only ultrasound abnormalities often showed a significant increase in fat fraction (22%) and signs of muscle oedema (44%) at five years;
- the fat fraction of muscles that initially had only an increase in fat fraction remained stable over time in 80% of cases and increased in the others; their EZ-score increased (23%), decreased (33%) or remained stable (44%).
Muscle ultrasound therefore appears to be useful in the early stages of the disease, whereas MRI seems better suited to late follow-up in facioscapulohumeral muscular dystrophy.
