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Appl Physiol Nutr Metab. 2016 Jan;41(1):70-5. doi: 10.1139/apnm-2015-0068. Epub 2015 Oct 7.

Use of prediction equations to determine the accuracy of whole-body fat and fat-free mass and appendicular skeletal muscle mass measurements from a single abdominal image using computed tomography in advanced cancer patients.

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a McGill Nutrition and Performance Laboratory, McGill University Health Centre, Montreal, QC H4A 3S5, Canada.
b Department of Exercise Science, Concordia University, 7141 Sherbrooke Street West, Montreal, QC H4B 1R6, Canada.
c Department of Radiology, McGill University Health Centre, Montreal, QC H3G 1A4, Canada.


Measurements of body composition using dual-energy X-ray absorptiometry (DXA) and single abdominal images from computed tomography (CT) in advanced cancer patients (ACP) have important diagnostic and prognostic value. The question arises as to whether CT scans can serve as surrogates for DXA in terms of whole-body fat-free mass (FFM), whole-body fat mass (FM), and appendicular skeletal muscle (ASM) mass. Predictive equations to estimate body composition for ACP from CT images have been proposed (Mourtzakis et al. 2008; Appl. Physiol. Nutr. Metabol. 33(5): 997-1006); however, these equations have yet to be validated in an independent cohort of ACP. Thus, this study evaluated the accuracy of these equations in estimating FFM, FM, and ASM mass using CT images at the level of the third lumbar vertebrae and compared these values with DXA measurements. FFM, FM, and ASM mass were estimated from the prediction equations proposed by Mourtzakis and colleagues (2008) using single abdominal CT images from 43 ACP and were compared with whole-body DXA scans using Spearman correlations and Bland-Altman analyses. Despite a moderate to high correlation between the actual (DXA) and predicted (CT) values for FM (rho = 0.93; p ≤ 0.001), FFM (rho = 0.78; p ≤ 0.001), and ASM mass (rho = 0.70; p ≤ 0.001), Bland-Altman analyses revealed large range-of-agreement differences between the 2 methods (29.39 kg for FFM, 15.47 kg for FM, and 3.99 kg for ASM mass). Based on the magnitude of these differences, we concluded that prediction equations using single abdominal CT images have poor accuracy, cannot be considered as surrogates for DXA, and may have limited clinical utility.


absorptiométrie à rayons X en double énergie; advanced cancer; appendicular skeletal muscle mass; cancer à un stade avancé; computed tomography; dual-energy X-ray absorptiometry; fat mass; fat-free mass; masse adipeuse; masse des muscles squelettiques appendiculaires; masse maigre; tomographie assistée par ordinateur

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