Assessing skeletal muscle radiodensity by computed tomography: An integrative review of the applied methodologies

Abstract

Low‐radiodensity skeletal muscle has been related to the degree of muscle fat infiltration and seems to be associated with worse outcomes. The aim of this study was to summarize the methodologies used to appraise skeletal muscle radiodensity by computed tomography, to describe the terms used in the literature to define muscle radiodensity and to give recommendations for its measurement standardization. An integrative bibliographic review in four databases included studies published until August 2019 in Portuguese, English or Spanish and performed in humans, adults and/or the elderly, of both sex, which investigated skeletal muscle radiodensity through computed tomography (CT) of the region between the third and fifth lumbar vertebrae and evaluated at least two muscular groups. One hundred and seventeen studies were selected. We observed a trend towards selecting all abdominal region muscle. A significant methodological variation in terms of contrast use, selection of skeletal muscle areas, radiodensity ranges delimitation and their cut‐off points, as well as the terminologies used, was also found. The methodological differences detected are probably due to the lack of more precise information about the correlation between skeletal muscle radiodensity by CT and its molecular composition, among others. Therefore, until the gaps are addressed in future studies, authors should avoid arbitrary approaches when reporting skeletal muscle radiodensity, especially when it comes to prognosis inference. Studies using both CT and direct methods of muscle composition evaluation are encouraged, to enable the definition and validation of the best approach to classify fat‐infiltrated muscle tissue, which will favour the nomenclature uniformization.

Skeletal muscle fat quantification by dual-energy computed tomography in comparison with 3T MR imaging

“…Regions of interest (ROIs) were defined on axial slices at the height of the third lumbar vertebra (LV3) (Fig. 1, marked by a white asterisk), as this is also the standard height for the determination of muscle quantity in single-energy CT [3,13] and drawn along the inner borders of the left and right posterior paraspinal muscles (m. erector spinae) (Fig. 2a, b).…”

“…An increase in intra-and extramyocellular fat has been shown to be indicative of a reduction in muscle quality [12]. Thus, studies on the ability of radiological descriptions of CT images or skeletal muscle mean radiation attenuation (SMRA) to assess the fat accumulation of the skeletal muscle have been performed [13]. While the former represents a subjective method, the determination of SMRA is semiquantitative, with values ranging between -190 and +150 Hounsfield units (HU) and a peak at 50 HU [14].…”

“…While the former represents a subjective method, the determination of SMRA is semiquantitative, with values ranging between -190 and +150 Hounsfield units (HU) and a peak at 50 HU [14]. Moreover, SMRA is influenced by the use of iodinated contrast agents [13]. Information regarding the use of such agents and phase acquisition are often missing in nonradiological papers on the clinical impact of SMRA values [13], which complicates comparability between studies.…”

“…Moreover, SMRA is influenced by the use of iodinated contrast agents [13]. Information regarding the use of such agents and phase acquisition are often missing in nonradiological papers on the clinical impact of SMRA values [13], which complicates comparability between studies.…”

Dual-Energy Computed Tomography for Fat Quantification in the Liver and Bone Marrow: A Literature Review

“…Die Eignung der DECT zur Bestimmung fetthaltiger und fettarmer Plaqueanteile in Gefäßen in vivo sollte entsprechend untersucht werden. Auch der Fettanteil im Skelettmuskel, der im Rahmen der Sarkopeniediagnostik bisher bildmorphologisch oder semiquantitativ über SECT-Abschwächungskoeffizienten bestimmt wird [47], könnte über die DECT quantifiziert werden.…”