• Muscle disease
• Alzheimer's disease
• nuclear medicine
• Parkinson's disease
• PET
• functional imaging
• neuropathology
• adrenoleukodystrophy
• genetics

A 55-year-old patient presented with progressive proximal tetraparesis since 2 months associated with erythematous rash and cuticular changes. Creatine kinase levels were elevated (2400 IU/l). Electromyography showed fibrillation and positive sharp wave potentials. Deltoid muscle biopsy showed evidence of dermatomyositis. Whole body fluorodeoxyglucose positron emission tomography (FDG-PET), performed to determine associated malignancy, did not show malignancy but showed increased muscular uptake (figure 1A). Oral prednisone 60 mg and azathioprine 100 mg was started. Two months later, muscle force and muscular FDG-PET uptake nearly normalised (figure 1B). Initial increased muscular FDG-PET uptake was probably related to myositis.1 Other possible conditions associated with increased muscular FDG-PET uptake include exertion, increased physiological uptake, hypoglycaemia and immunosuppressive therapy.2

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Figure 1

Initial whole body FDG-PET showing diffuse, increased, proximal predominant, muscular uptake (A, arrows). Focal increased uptake in the proximal right arm (A, arrowhead) was probably related to the right deltoid muscle biopsy 3 weeks earlier. Two months later, whole body FDG-PET nearly normalised (B).