All 309 patients were clinically managed in our institution,
a tertiary muscle disease unit. Causes for myositis based on our experience included:
-Autoimmune: Graft versus host disease,
Grave’s and Crohn’s disease.
-Infection: Bacterial,
fungal,
parasitic and viral.
Cases included HIV,
pyomyositis and necrotising fasciitis.
-Drug-induced:
1.
Recreational substance abuse such as cocaine or steroid
2.
Iatrogenic: Statins,
rituximab,
anti-retrovirals,
autoimmune therapy.
-Post traumatic: rhabdomyolysis,
myositis ossificans and haematomas of variable chronicity
-Nerve entrapments
-Demyelinating disease
-Neuromuscular inherited disorders such as Duchene muscle dystrophy
-Tumours: Myosarcoma,
lymphoma,
Kaposi and metastasis.
-Inflammatory: polymyositis,
dermatomyositis and sarcoidosis.
-Vasculitis: including diabetic myonecrosis,
muscle infarcts and ischaemia.
-Inclusion body myositis
-Collagen vascular diseases: including SLE and sjogren’s
-Radiation induced myositis
Our imaging protocols include multiplanar MRI imaging with T1WI,
STIR and post contrast imaging (T1FS pre and post contrast).
In some cases,
DWI imaging,
Dixon sequences and spectroscopy is performed for evaluation of cellularity,
perfusion and molecular changes.
Ultrasound imaging is useful for interval scanning to assess interval change.
SMi,
Doppler and Power Doppler helps evaluate the extent of vascularity and inflammation.
Panoramic imaging is used to assess patterns,
pennation angles,
architecture of muscles and volume.