[Non-invasive imaging of chronic inflammatory myopathies]

In patients with chronic inflammatory myositis noninvasive diagnostic modalities, such as magnetic resonance (MR) imaging, and ultrasonography (US), are able to demonstrate muscular edema, fluid collections, fatty infiltration, atrophy, fibrosis, and calcifications. Because MR imaging is sensitive to the presence of edema and offers better tissue differentiation, current MR imaging with fat suppressed T2-weighted techniques or STIR images appears to be more efficient than US in the diagnosis and management of inflammatory myopathies. MR imaging has also been proposed as a means to guide biopsy in an area of active disease, thereby reducing the problem of sampling error. These changes in signal intensity, however, are not specific for myositis. Although MR imaging is now the imaging modality of choice in this issue, reduced availability, patient discomfort, and exclusion of certain patients with indwelling metal objects, such as pacemakers, are disadvantages. The availability and ease of use of US makes it preferable to MR imaging. Real-time sonoelastography can be used for various musculoskeletal applications, but the clinical utility in diagnosis of myositis is yet to be established. On the other hand, the contrast-enhanced US is a feasible method for noninvasively demonstrating increased perfusion in the involved muscle groups, and most likely, will soon become preferable, noninvasive imaging method in patients with myositis.