The thickness of erector spinae muscles can be easily measured by computed tomography for the assessment of physical activity: An observational study

The loss of muscle mass and changes in muscle composition are important factors for assessing skeletal muscle dysfunction. The cross-sectional area (CSA) of muscle is usually used to assess skeletal muscle function. However, the CSA of skeletal muscle can be difficult for clinicians to measure because a specific 3D image analysis system for computed tomography (CT) scans is needed. Therefore, we conducted a study to develop a new method of easily assessing physical activity, in which the thickness of the erector spinae muscles (ESM T ) was measured by CT, and to compare ESM T to the CSA of the erector spinae muscles (ESM CSA ) in patients with nontuberculous mycobacteria (NTM) pulmonary infections who underwent surgery after some preoperative examinations, such as laboratory tests, chest CT scans, spirometry, and 6-minute walk tests (6MWT). We retrospectively studied adult patients with NTM pulmonary infections who underwent a lobectomy at Fukujuji Hospital from April 2010 to March 2016. We assessed the correlations between ESM T and different variables, including ESM CSA . Sixty-one patients with NTM pulmonary infections were included. The median ESM T and ESM CSA were 1371 mm 2 (IQR 1178–1784 mm 2 ) and 28.5 mm (IQR 25.4–31.7 mm), respectively, and a very strong linear correlation was observed between ESM T and ESM CSA ( R = 0.858, P