Validation of an elliptical anthropometric model to estimate visceral compartment area

Objective: The visceral compartment is a surrogate for visceral adipose tissue. Cross-sectional visceral compartment area (VCA) has been approximated from waist circumference using a circular model. However, the two-dimensional shape of the abdomen is rarely circular. This study validated an elliptical model of cross-sectional total abdominal area (TAA), subcutaneous adipose tissue (SAT) area, and VCA at the L₄-L₅ level. Research Methods and Procedures: We analyzed magnetic resonance images (MRIs) at the level of the L₄-L₅ intervertebral space from 35 subjects with a wide range of abdominal adiposity. Waist circumference, abdominal thickness (midline sagittal diameter), abdominal width (coronal diameter at one-half of abdominal thickness), and abdominal SAT thickness at four sites (front, back, right, and left) were measured from MRI images using an image analysis software. The same anatomical regions were also estimated from anthropometrics purely by geometric formulae of circular and elliptical models. A simple linear regression model was used to interpret the association strength between anthropometric estimates and MRI measures. Results: Estimated TAA by either model was strongly related to MRI TAA (r² = 0.98, p < 0.0001). The SAT and VCA by MRI analysis showed a stronger association with calculation from an elliptical model (r ² = 0.95 and 0.88, respectively; p < 0.001) than a circular model (r² = 0.69 and 0.25, respectively; p < 0.001). The absolute prediction residuals and variances were significantly smaller with an elliptical model than a circular model (p < 0.0001). Discussion: An elliptical anthropometric model might be superior to a circular model to estimate abdominal SAT and VCA.