SAGITTAL DIAMETER IN COMPARISON WITH SINGLE SLICE CT AS A PREDICTOR OF TOTAL VISCERAL ADIPOSE-TISSUE VOLUME

BACKGROUND: Abdominal obesity has an important biological and epidemio logical relationship to disease. The gold standard for measurement of visceral adipose tissue (VAT) is assessment by computerized tomography (CT) or magnetic resonance imaging (MRI), but because of simplicity a nd ease in collection, anthropometric variables are a desirable altern ative to estimate VAT. OBJECTIVE: To compare the abilities of a single slice CT scan through the L4-L5 interspace (L4-L5 VAT), sagittal diam eter, and body mass index (BMI) to estimate total volume VAT. Total vo lume VAT (the gold standard) was measured by total abdominal CT scanni ng, with a mean of 42 CT slices per patient. Estimation of VAT in subj ects of similar body size was emphasized. DESIGN: Retrospective study of subjects undergoing complete abdominal and pelvic CT scanning for c linical reasons. SUBJECTS: 40 subjects (20 men and 20 women) mean age 56.5 y, with a balanced selection for BMI < 27 and > 27. RESULTS: In u nivariate regression models, L4-L5 VAT explained the largest proportio n of the variance in total VAT (R-2 = 0.87 (P < 0.001)), though age (R -2 = 0.11 (P = 0.04)), BMI (R-2 = 0.37 (P < 0.001)), and sagittal diam eter (R-2 = 0.50 (P < .001)) were also statistically significantly rel ated to total VAT. When limited to individuals with a BMI greater than or equal to 27 however, L4-L5 VAT explained a large proportion of the variance in total VAT (R-2 = 0.87 (P < 0.001)) whereas sagittal diame ter was only of borderline significance (R-2 = 0.20 (P = 0.06)), and B MI was not associated with total VAT (R-2 = 0.04 (P = NS)). In multipl e regression analyses, L4-L5 VAT area explained a large proportion of the variance (0.84-0.90), and once in the model, BMI, sagittal diamete r, and age did not additionally contribute significantly to the explai ned variance in total VAT. CONCLUSIONS: Abdominal sagittal diameter is poorly correlated to total VAT for men and women with a BMI > 27. Wit hin a 2 cm range of sagittal diameter, there is nearly a three-fold va riability in total VAT.