Skeletal muscle quality by computed tomography: integrative review of the methodological perspectives and conceptual evolution

Abstract

Background & Aims: Low skeletal muscle (SM) quality may be related to the degree of muscle fat infiltration and seems to be associated to worse outcomes. The aim of this study was to summarize the methodologies for indirect evaluation of SM fat infiltration using computed tomography (CT), as well as to describe the evolution of the terms used in the literature to define muscle quality by this method. Methods: An integrative bibliographic review in four databases included studies published until August 2018 in Portuguese, English or Spanish; performed in humans, adults and/or elderly, of both sex; which investigated SM quality through CT of the region between the third and fifth lumbar vertebrae and evaluated at least two muscular groups. Results: Sixty-seven studies were selected. A methodological standardization trend was observed in determining the abdominal region and the evaluated muscle groups. However, the most significant methodological variations concern the classification of SM quality, such as, the selection of SM areas, radiodensity ranges delimitation and their cut-off points, as well as the terminologies used. Conclusions: The methodological differences detected are probably due to the lack of more precise information about the correlation between SM radiodensity by CT and its composition. Therefore, recommendations were made to be followed until new studies considering the mentioned factors correct these gaps.