Body composition analysis: Single slice vs. volumetric measures

Body composition analysis (BCA) is useful for evaluating nutritional status, general health, and predicting patient outcomes. Computed tomography (CT)-based BCA has become increasingly popular, with research often focusing on single-transaxial-slice measurements at the L3 vertebral level to estimate volumetric tissue properties. This method assumes the same tissue distribution in all transaxial slices across the body, potentially leading to inaccuracies in clinical assessments. This retrospective study investigates the reliability of single-slice BCA compared to volumetric measurements across the torso in a cohort of 237 adults. Using the GA-Net architecture for automatic tissue segmentation, we analyzed tissue distribution at 25 craniocaudal levels. Our results reveal significant variability in tissue distribution, with cross-sectional areas at L3 poorly correlating with 3D tissue volumes. For instance, we observed a visceral adipose tissue (VAT) volume difference of over 2,900 cm³ between two subjects with similar L3 VAT areas. These findings indicate that single-slice BCA, particularly at L3, is insufficient for accurate body composition analysis. This study underscores the need for more precise, volumetric approaches to BCA, which would enhance the accuracy of clinical assessments, disease prognostication, and treatment planning.