Abstract 9360: Dual-Energy X-ray Absorptiometry for Quantification of Visceral Adipose Tissue

Background: Obesity is the major risk factor for metabolic syndrome and through it diabetes as well as cardiovascular disease. Visceral fat (VF) rather than subcutaneous fat (SF) is the major predictor of adverse events. Currently the gold standard for measuring VF is abdominal x-ray computed tomography (CT), which exposes patients to significant amounts of radiation and is relatively time-consuming. Dual-energy x-ray absorptio-metry (DXA) can accurately measure body composition with high precision, low x-ray exposure and short scanning time. The purpose of this study was to validate a new method whereby VF can be measured by DXA. Methods: We studied124 adult men and women volunteers, aged 18 to 90 years, representing a wide range of BMI values (18.5 to 40 kg/m 2 ) who underwent DXA and CT in a fasting state within one hour of each other. The DXA VF algorithm uses measurements of the total abdominal thickness, based on x-ray attenuation, and the width of the SF layer along the lateral extent of the abdomen along with geometric constants to estimate SF in the android region. VF is computed by subtracting SF from the total fat in the android region. Results: Our results are depicted in the Figure. The coefficient of determination (r²) for regression of CT on iDXA values was 0.959 for females, 0.949 for males and 0.957 combined. The 95% confidence interval for r was 0.968 to 0.985 for the combined data. The 95% confidence interval for the mean of the differences between CT and iDXA VF volume was -96.0 to - 16.3 cm³. Bland-Altman bias was +67 cm³ for females and +43 cm³ for males. The 95% limits of agreement were -339 to +472 cm³ for females and -379 to +465 cm³ for males. Combined, the bias was +56 cm³ with 95% limits of agreement of -355 to +468 cm³. Conclusion: We conclude that DXA can measure VF precisely in both men and women. This simple non-invasive method can therefore be used to measure VF in individual patients and help define cardiovascular risk.