Cigarette smoking and disproportionate changes of thoracic skeletal muscles in low-dose chest computed tomography

Figures

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  Figure 1. Study flow diagram.

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  Figure 2. The quantity and quality of skeletal muscles according to smoking intensity: (a) skeletal muscle at the first lumbar vertebra level (L1-SMI, skeletal muscle index at the first lumbar vertebra; L1-SNAMA%, percentage of normal attenuation skeletal muscle area at the first lumbar vertebra), (b) thoracic skeletal muscle at the carina level (C-TSMI, thoracic skeletal muscle index at the carina; C-TSNAMA%, percentage of normal attenuation thoracic skeletal muscle area at the carina), (c) pectoralis muscle at the aortic arch level (AA-PMI, pectoralis muscle index at the aortic arch; AA-PNAMA%, normal attenuation pectoralis muscle area at the aortic arch), and (d) erector spinae muscle at the 12th thoracic vertebra level (T12-ESMI, erector spinae muscle index at the 12th thoracic vertebra; T12-ESNAMA%, percentage of normal attenuation erector spinae muscle area at the 12th thoracic vertebra).

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  Figure 3. Disproportionate skeletal muscles wasting according to smoking intensity: (a) C/L ratio (thoracic skeletal muscle index at the carina to skeletal muscle index at the first lumbar [L1-SMI] ratio), (b) A/L ratio (pectoralis muscle index at the aortic arch to L1-SMI ratio), and (c) T/L ratio (erector spinae muscle index at the 12th thoracic vertebra to L1-SMI ratio).

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  Figure 4. Thoracic skeletal muscle change in a current smoker: In a 68 year-old current smoker with 40 pack-year (body weight 58.2 kg, height 157.4 cm, body-mass index 23.5 kg/m2) showed severe degree of centrilobular emphysema, total lung capacity of 4.3L, and 5.22 mm of the square root of the wall area at internal perimeter of 10 mm: (a,b) pectoralis muscle index at the aortic arch (AA-PMI) and percentage of normal attenuation pectoralis muscle area at the aortic arch (AA-PNAMA%) were 10.7cm2/m2 and 61.4%, respectively; (c,d) thoracic skeletal muscle index at the carina (C-TSMI) and percentage of normal attenuation thoracic skeletal muscle area at the carina (C-TSNAMA%) were 34.4cm2/m2 and 47.6%, respectively; and (e,f) erector spinae muscle index at the 12th thoracic vertebra (T12-ESMI) and percentage of normal attenuation erector spinae muscle area at the 12th thoracic vertebra (T12-ESNAMA%) were 13.9cm2/m2 and 65.8%, respectively. The SMI at the first lumbar vertebra (L1-SMI) and percentage of normal attenuation skeletal muscle area at the first lumbar vertebra (L1-SNAMA%) were 42.1cm2/m2 and 53.5%, respectively (not presented).

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  Figure 5. Thoracic skeletal muscle change in a non-smoker: In a 69 year-old men without documented smoking history (body weight 71 kg, height 172.7 cm, body-mass index 23.8 kg/m2) showed absence of centrilobular emphysema, total lung capacity of 5.2L, and 5.06 mm of square root of the wall area at internal perimeter of 10 mm: (a,b) pectoralis muscle index at the aortic arch (AA-PMI) and percentage of normal attenuation pectoralis muscle area at the aortic arch (AA-PNAMA%) were 13.9cm2/m2 and 77.8%, respectively; (c,d) thoracic skeletal muscle index at the carina (C-TSMI) and percentage of normal attenuation thoracic skeletal muscle area at the carina (C-TSNAMA%) were 36.4cm2/m2 and 64.7%, respectively; and (e,f) erector spinae muscle index at the 12th thoracic vertebra (T12-ESMI) and percentage of normal attenuation erector spinae muscle area at the 12th thoracic vertebra (T12-ESNAMA%) were 12.2cm2/m2 and 77.6%, respectively. The SMI at the first lumbar vertebra (L1-SMI) and percentage of normal attenuation skeletal muscle area at the first lumbar vertebra (L1-SNAMA%) were 40.6cm2/m2 and 68.4%, respectively (not presented).