Imaging beyond muscle magnetic resonance imaging in inclusion body myositis

Diagnosis of inclusion body myositis (IBM), the most common acquired muscle disorder in adults above the age of 40, remains dependent on demonstration of the classic clinical phenotype and confirmed by muscle histopathological examination. The European Neuromuscular Centre (ENMC) 2011 diagnostic criteria for the diagnosis of IBM includes the demonstration of one or more of the muscle pathological findings - inflammation, vacuolation or protein aggregation. Muscle biopsy is an invasive procedure and patients often require more than one biopsy to establish a definitive diagnosis of IBM. Over the past few years, there has been considerable gain in knowledge regarding various imaging modalities that may complement the diagnosis of IBM, and in some cases have the potential to obviate the need for more invasive procedures, such as muscle biopsy. Positron emission tomography (PET) using different ligands may serve as a surrogate biomarker of therapeutic target engagement in IBM. This review concentrates on a critical evaluation of the literature looking at the utility of muscle ultrasound, dual energy x-ray absorptiometry (DEXA), and positron emission tomography and their role in IBM.