Relationship between dual-energy X-ray absorptiometry volumetric assessment and X-ray computed tomography-derived single-slice measurement of visceral fat

To reduce radiation exposure and cost, visceral adipose tissue (VAT) measurement on X-ray computed tomography (CT) has been limited to a single slice. Recently, the US Food and Drug Administration has approved a dual-energy X-ray absorptiometry (DXA) application validated against CT to measure VAT volume. The purpose of this study was to develop an algorithm to compute single-slice area values on DXA at 2 common landmarks, L_2/3 and L_4/5, from an automated volumetrically derived measurement of VAT. Volumetric CT and total body DXA were measured in 55 males (age: 21-77 yr; body mass index [BMI]: 21.1-37.9) and 60 females (age: 21-85 yr; BMI: 20.0-39.7). Equations were developed by applying the relationship of CT single-slice area and volume measurements of VAT to the DXA VAT volume measure as well as validating these against the CT single-slice measurements. Correlation coefficients between DXA estimate of single-slice area and CT were 0.94 for L_2/3 and 0.96 for L_4/5. The mean difference between DXA estimate of single-slice area and CT was 5 cm² at L_2/3 and 3.8 cm² at L_4/5. Bland-Altman analysis showed a fairly constant difference across the single-slice range inthisstudy, and the 95% limits of agreement for the 2 methods were -44.6 to +54.6 cm² for L_2/3 and -47.3 to+54.9 cm² for L_4/5. In conclusion, a volumetric measurement of VAT by DXA can be used to estimate single-slice measurements at the L_2/3 and the L_4/5 landmarks.