Imaging of sarcopenia.

Sarcopenia is currently considered a geriatric syndrome increasing in older people. The consequences of sarcopenia - in terms of impaired mobility, limited self-sufficiency and disability - have been amply demonstrated, increasing the need to develop methods to identify muscle mass loss as early as possible. Although sarcopenia involves a reduction in both muscle mass and function, loss of muscle mass remains the essential criterion for diagnosing this condition in daily practice. Computed tomography and magnetic resonance imaging represent the gold standard for studying body composition, and can identify quantitative and qualitative changes in muscle mass. These techniques are costly, time-consuming and complex, however, so their applicability is limited to the research field. Sonography, on the other hand, has the advantage of being a relatively quick and inexpensive method for detecting loss of muscle fibers and fat infiltration by analyzing muscle thickness and echo intensity. To the best of our knowledge, however, only few studies have compared the results of ultrasound with those obtained by other methods in order to establish its reliability in this setting. Dual X-ray absorptiometry thus remains the most often used technology for studying body composition, detecting quantitative changes in muscle mass with the advantages of a low radiation dose, a simple technology and a rapid assessment.