Computed tomography-measured adipose tissue attenuation and area both predict adipocyte size and cardiometabolic risk in women

Abstract

Objective: To assess the ability of CT-derived measurements including adipose tissue attenuation and area to predict fat cell hypertrophy and related cardiometabolic risk.

Methods: Abdominal adipose tissue areas and radiologic attenuation were assessed using 4 CT images in 241 women (age: 47 years, BMI: 26.5 kg/m(2)). Fat cell weight was measured in paired VAT and SAT samples. Fasting plasma lipids, glucose and insulin levels were measured.

Results: Adipose tissue attenuation was negatively correlated with SAT (r=-0.46) and VAT (r=-0.67) fat cell weight in the corresponding depot (p<0.0001 for both). Women with visceral adipocyte hypertrophy had higher total-, VLDL-, LDL- and HDL-triglyceride and apoB levels as well as a higher cholesterol/HDL-cholesterol ratio, fasting glucose and insulin levels compared to women with smaller visceral adipocytes. Adjustment for VAT area minimized these differences while subsequent adjustment for attenuation eliminated all differences, with the exception of fasting glycaemia. In SAT, adjustment for VAT area and attenuation eliminated all adipocyte hypertrophy-related alterations except for fasting hyperglycaemia.

Conclusion: CT-derived adipose tissue attenuation and area both contribute to explain variation in the cardiometabolic risk profile associated with the same biological parameter: visceral fat cell hypertrophy.

Keywords: adipose tissue radiologic attenuation; computed tomography; omental adipocytes; visceral fat; women.

Figure 1.

Correlations between SAT (A) or VAT (B) attenuation and adipose tissue area in the corresponding depot; between SAT (C) or VAT (D) areas and adipocyte weight in the corresponding depot; and between SAT (E) or VAT (F) attenuation and adipocyte weight in the corresponding depot. Spearman correlation coefficients were computed to test associations. P-values lower than 0.05 were considered statistically significant. Linearity testing indicated a significant order 2 for panels A and B, linear relationship for panels C, D and F, and a significant order 3 for panel E.

Figure 2.

Cardiometabolic risk profile in subgroups of women defined on the basis of their VAT fat cell weight (low vs. high) using the median value of VAT fat cell weight as cutoff, before (Unadj) and after (Adj) statistical adjustments for adipose tissue area or adipose tissue area and attenuation. Differences between subgroups were tested using Student’s t-test. Adjustment for VAT area and adjustment for both VAT area and radiologic attenuation were performed using multiple regression analysis. P-values lower than 0.05 were considered statistically significant. chol: cholesterol.

Figure 3.

Cardiometabolic risk profile in subgroups of women defined on the basis of their SAT fat cell weight (low vs. high) using the median value of SAT fat cell weigh as cutoff, before (Unadj) and after (Adj) statistical adjustments for adipose tissue area or adipose tissue area and attenuation. Differences between subgroups were tested using Student’s t-test. Adjustment for VAT area and adjustment for both VAT area and radiologic attenuation were performed using multiple regression analysis. P-values lower than 0.05 were considered statistically significant. chol: cholesterol.