Approaches to Assessment of Muscle Mass and Myosteatosis on Computed Tomography (CT): A Systematic Review.

There is increasing use of computed tomography (CT) in sarcopenia research using a wide variety of techniques. We performed a systematic review of the CT literature to identify the differences between approaches used. A comprehensive search of PubMed from 1983-2017 was performed to identify studies that used CT muscle measurements to assess muscle mass and myosteatosis. The CT protocols were evaluated based on: anatomic landmark(s), thresholding, muscle(s) segmented, key measurement (i.e., muscle attenuation, cross-sectional area, volume), derived variables, and analysis software. From the described search, 657 articles were identified and 388 studies met inclusion criteria for this systematic review. Muscle mass was more commonly assessed than myosteatosis (330 vs 125). The most commonly assessed muscle or muscle groups were total abdominal wall musculature (142/330 and 49/125 for muscle mass and myosteatosis, respectively) and total thigh musculature (90/330 and 48/125). The most commonly used landmark in the abdomen was the L3 vertebra (123/142 and 45/49 for muscle mass and myosteatosis, respectively). Skeletal muscle index (SMI) and inter-muscular adipose tissue (IMAT) were the most commonly used measures of abdominal wall muscle mass (114/142) and myosteatosis (27/49), respectively. Cut-points varied across studies. A significant majority of studies failed to report important CT technical parameters, such as use of intravenous contrast and slice thickness (94% and 63%, respectively). There is considerable variation in the CT approaches used for the assessment of muscle mass and myosteatosis. There is a need to develop consensus for CT-based evaluation of sarcopenia and myosteatosis.