Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 6/20/2004
Publication Date: 10/25/2004
Citation: Ellis, K.J., Grund, B., Visnegarwala, F., Mullin, C., Miller, C.G., Chesson, C.E., El-Sadr, W., Carr, A. 2004. Abdominal subcutaneous adipose tissue (SAT) and viceral adipose tissue (VAT) measurements in HIV+ adults: Influences of measurement site [abstract]. Antiviral Therapy. 9(6):L34. Interpretive Summary:
Technical Abstract: Loss of SAT and an increase in VAT are common with HIV lipodystrophy. Excess abdominal VAT is a known risk factor for cardiovascular disease. Computerized axial tomography (CT) can be used to measure SAT and VAT areas in cross-sectional images of the abdomen. The ideal site(s) and number of abdominal images required to measure SAT and VAT is unknown. We obtained nine-slice abdominal CTs in 26 HIV+ adults, one at the intervertebral L2–L3, L3–L4 and L4–L5 spaces, and two additional slices 7 mm superior and inferior to each space. We assessed the interchangeability among the three intervertebral sites, and determined the effects of imprecise positioning for each site. Mean ±SD values (cm2) for SAT were 100 ±52 at L2–L3, 120 ±55 at L3–L4 and 150 ±69 at L4–L5, indicating a 50% increase when moving lower on the abdomen. In contrast, the corresponding mean VAT values were 178 ±129, 165 ±113 and 134 ±84 cm2, or a 25% decrease at the lowest position. Also, the mean VAT/SAT ratios decreased across the three intervertebral sites: 2.15 ±1.75 at L2–L3, 1.68 ±1.46 at L3–L4 and 1.03 ±0.75 at L4–L5. At each site, analysis of variance (ANOVA) confirmed the significant differences between superior, central and inferior slices for SAT (P<0.0001) and VAT (P<0.01). The magnitude of the differences in abdominal VAT and SAT values between the three intervertebral sites precludes their interchangeability for the assessment of abdominal SAT and VAT. Using the VAT/SAT ratio does not overcome this limitation. Furthermore, the substantial differences in SAT and VAT values between the three slices at an intervertebral site indicate that precise re-positioning of the scans is needed for longitudinal studies. In summary, our findings suggest that nine-slice abdominal CT at three intervertebral levels provides a more complete assessment of abdominal fat distribution than does single-slice CT.