Diagnosis of common muscular dystrophies such as myotonic dystrophy type 1, facio-scapulo-humeral muscular dystrophy and oculopharyngeal muscular dystrophy is usually based on classical clinical findings. Therefore, in these muscular dystrophies the role of muscle imaging has yet to be defined. Recent studies performed on these myopathies suggested that some characteristic findings are present, even if there is less diagnostic value compared with CM, LGMD and MFM (Fig. 6).
Fig. 6 Muscle MRI of lower extremities in other muscular dystrophies. Myotonic dystrophy type I (a) is typically characterised by distal more than proximal muscle involvement showing predominant affliction of the soleus, medial gastrocnemius and proximally the anterior thigh compartment with relative sparing of the rectus femoris. Patients with myotonic dystrophy type II (or proximal myotonic myopathy = PROMM) (b) are often less affected and show no fatty degeneration. Affected patients show more involvement of the proximal muscles with affliction of the quadriceps and sparing of the rectus femoris and gracilis muscles. FSHD (c) patients are often characterised by marked asymmetry with the adductor magnus, hamstrings, rectus femoris and tibial anterior being the most frequently affected muscles. OPMD (d) patients show predominantly posterior thigh (adductor magnus, semimembranosus and biceps femoris muscles) and posterior lower leg (soleus) muscle involvement