Methods of estimation of visceral fat: advantages of ultrasonography

To compare methods for the assessment of visceral fat with computed tomography (CT) and establish cutoffs to define visceral obesity based on such alternative methods.

One hundred women (50.4 +/- 7.7 years; BMI 39.2 +/- 5.4 kg/m2 underwent anthropometric evaluation, bioelectrical impedance, DXA, abdominal ultrasonography (US), and CT scan.

Waist circumference, waist-to-hip ratio (WHR), and US-determined visceral fat values showed the best correlation coefficients with visceral fat determined by CT (r = 0.55, 0.54, and 0.71, respectively; p < 0.01). Fat mass determined by DXA was inversely correlated with visceral-to-subcutaneous-fat ratio (r = -0.47, p < 0.01). Bioimpedance-determined fat mass and skinfolds were correlated with only subcutaneous abdominal fat quantified by CT. Linear regression indicated US visceral-fat distance and WHR as the main predictors of CT-determined visceral fat (adjusted r2 = 0.51, p < 0.01). A waist measurement of 107 cm (82.7% specificity, 60.6% sensitivity) and WHR of 0.97 (78.8% specificity, 63.8% sensitivity) were chosen as discriminator values corresponding with visceral obesity diagnosed by CT. A value of 6.90 cm for visceral fat US-determined diagnosed visceral obesity with a specificity of 82.8%, a sensitivity of 69.2%, and a diagnostic concordance of 74% with CT.

US seemed to be the best alternative method for the assessment of intra-abdominal fat in obese women. Its diagnostic value could be optimized by an anthropometric measurement. Prospective studies are needed to establish CT and US cutoffs for defining visceral-fat levels related to elevated cardiovascular risk.