PET/CT imaging in inflammatory myopathies

Inflammatory muscle diseases are a group of muscle disorders characterized by muscle weakness, fatigue, and an association with malignancy and paraneoplastic syndrome. A diagnosis of idiopathic inflammatory myopathy is suggested by abnormal myometry and rising creatine kinase, but tissue diagnosis is also needed. Magnetic resonance imaging (MRI) helps localize the appropriate site of biopsy, demonstrate the extent of muscle involvement, and monitor the response to therapy. However, the sensitivity of magnetic resonance (MR) is limited, and whole-body imaging is still far from routine. [F-18]Fluoro-desoxy-glucose (FDG) positron emission tomography (PET)/computed tomography (CT) is currently the ultimate metabolic imaging technique for the management of cancer. It has also been shown to detect inflammatory conditions and to monitor their response to treatment. The use of FDG PET in screening for underlying malignancies is widely reported and recommended in patients with paraneoplastic syndrome. Unfortunately, only a few reports have been published to show the value of FDG PET in inflammatory muscle diseases, which as we show herein, deserve further pursuit.