Objectives: Aim of the study was to assess the potential value of cross-sectional adipose tissue evaluation in well defined single transverse slices for estimation of volumes of metabolically important adipose tissue compartments as visceral adipose tissue (VAT), nonvisceral adipose tissue (NVAT), and total body adipose tissue (TAT). In addition, validity of easily accessible anthropometric indices (waist-to-hip-ratio [WHR] and body mass index [BMI]) for prediction of volumes of those adipose tissue compartments were validated and compared.
Materials and methods: True volumes of main adipose tissue compartments VAT, TAT, and NVAT were carefully assessed based on whole-body magnetic resonance (MR) examinations in 367 volunteers (227 females, 140 males, age 18-69 years) at increased risk for type 2 diabetes. Volumes of VAT, NVAT, and TAT were compared with cross-sectional areas of adipose tissue in single transverse slices recorded on the level of (1) umbilicus (u), (2) head of humerus (h), (3) head of femur (f), and anthropometric data such as BMI and WHR. Separate analyses were performed in males and females.
Results: In both genders, strong correlations were found between TAT and the cross-sectional areas: subcutaneous adipose tissue (u) with r = 0.88 in females and r = 0.92 in males, TAT(h) with r = 0.80 in females and r = 0.82 in males, and TAT(f) with r = 0.90 in females and r = 0.90 in males. VAT assessed by MR single slice evaluation at the umbilical level (VAT(u)) showed a strong correlation with total VAT in both genders (r = 0.93 in females, r = 0.87 in males). Suitable algorithms for predicting VAT in liter from fat planimetry in a slice recorded at the umbilical level were derived: VAT = 0.16 x (VAT(u) x body height) + 0.3 in women and VAT = 0.15 x (VAT(u) x body height) + 1.2 in men. Disregarding the body height, the best equations were as follows: VAT = 0.03 x VAT(u) + 0.3 in women and VAT = 0.02 x VAT(u) + 1.4 in men. In contrast, BMI versus VAT showed a lower correlation in both genders: r = 0.71 in females, r = 0.56 in males, and WHR versus VAT was only weakly correlated in females and in males (r = 0.49 and r = 0.55, respectively). For WHR versus TAT, significant results were only found in males (r = 0.44).
Conclusions: Axial MRI at the umbilical level allowed for a fast and reliable estimation, especially for VAT and TAT in a collective at risk for type 2 diabetes. WHR and BMI were found clearly worse in prediction of VAT volumes compared with single slice evaluation at the umbilical level.