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Diagnosing Sarcopenia on Thoracic Computed Tomography: Quantitative Assessment of Skeletal Muscle Mass in Patients
Ursula Nemec1, Benedikt Heidinger1, Claire Sokas2
1Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Ave, Boston, MA 02115.
Rationale And Objectives:
This study aims to assess the use of skeletal muscle mass measurements at two thoracic levels to diagnose sarcopenia on computed tomography (CT) chest examinations and to analyze the impact of these measurements on clinical outcome parameters following transcatheter aortic valve replacement.
Materials And Methods:
This study retrospectively included 157 patients who underwent preoperative CT examinations. The total muscle area was measured on transverse CT images at the 3rd lumbar and 7th and 12th thoracic levels with skeletal muscle indices (SMIs) calculated at each level. SMIs were then compared to clinical outcome parameters, and thoracic cutoff values for sarcopenia at the 7th and 12th thoracic levels were calculated.
Results:
Correlation between SMIs at the third lumbar vertebra (L3) and the 12th thoracic vertebra (T12) was stronger (r = 0.724, P < 0.001) than that between L3 and the seventh thoracic vertebra (T7) (r = 0.594, P < 0.001). SMIs at L3 and T12 significantly correlated with prolonged length of stay. Thoracic cutoff values for the 12th thoracic level were 42.6 cm2/m2 (men) and 30.6 cm2/m2 (women), and those for the 7th thoracic level were 46.5 cm2/m2 (men) and 32.3 cm2/m2 (women).
Conclusions:
Skeletal muscle measurements at the T12 level could permit the diagnosis of sarcopenia and could be used to correlate sarcopenia with outcome parameters in patients undergoing CT limited to the chest.