Ultrasonography for the evaluation of visceral fat and cardiovascular risk

Visceral fat accumulation is associated with increased cardiovascular risk. Clinical evaluation of visceral fat is limited because of the lack of reliable and low-cost methods. To assess the correlation between ultrasonography and computed tomography (CT) for the evaluation of visceral fat, 101 obese women, age 50.5+/-7.7 years with a body mass index of 39.2+/-5.4 kg/m(2), were submitted to ultrasonograph and CT scans. Visceral fat measured by ultrasonography, 1 cm above the umbilical knot, showed a high correlation with CT-determined visceral fat (r=0.67, P<0.0001). The ultrasonograph method showed good reproducibility with an intra-observer variation coefficient of <2%. Both ultrasonograph and CT visceral fat values were correlated with fasting insulin (r=0.29 and r=0.27, P<0.01) and plasma glucose 2 hours after oral glucose load (r=0.22 and r=0.34, P<0.05), indicating that ultrasonography is a useful method to evaluate cardiovascular risk. A significant correlation was also found between visceral fat by CT and serum sodium (r=0.18, P<0.05). A ultrasonograph-determined visceral-to-subcutaneous fat ratio of 2.50 was established as a cutoff value to define patients with abdominal visceral obesity. This value also identified patients with higher levels of plasma glucose, serum insulin and triglycerides and lower levels of HDL-cholesterol, which are metabolic abnormalities characteristic of the metabolic syndrome. Our data demonstrate that ultrasonography is a precise and reliable method for evaluation of visceral fat and identification of patients with adverse metabolic profile.