The clinical importance of visceral adiposity: a critical review of methods for visceral adipose tissue analysis

Abstract

As a result of the rising epidemic of obesity, understanding body fat distribution and its clinical implications is critical to timely treatment. Visceral adipose tissue is a hormonally active component of total body fat, which possesses unique biochemical characteristics that influence several normal and pathological processes in the human body. Abnormally high deposition of visceral adipose tissue is known as visceral obesity. This body composition phenotype is associated with medical disorders such as metabolic syndrome, cardiovascular disease and several malignancies including prostate, breast and colorectal cancers. Quantitative assessment of visceral obesity is important for evaluating the potential risk of development of these pathologies, as well as providing an accurate prognosis. This review aims to compare different methods of measuring visceral adiposity with emphasis on their advantages and drawbacks in clinical practice.

Figures

Figure 1

Dual energy X-ray absorptiometry of the whole body. Regional image analysis of the visceral fat is conducted at the level of L3–L5 lumbar vertebrae (green rectangle).

Figure 2

Ultrasound image of the abdomen. (a,b) Subcutaneous fat (S) and a pre-peritoneal fat layer (P) extending from the anterior surface of the liver to the linea alba (white arrow) are identified. The abdominal wall fat index designates a ratio of the thicknesses of the pre-peritoneal fat layer and subcutaneous fat; (c) visceral thickness (green arrow) from the posterior edge of the abdominal muscles to the aorta (white arrow) is also demonstrated.

Figure 3

Axial CT images of the abdomen at the level of the L3 vertebral body. (a) Visceral, (b) subcutaneous and (c) total fat components are highlighted. (d) Visceral, (e) subcutaneous and (f) total fat components are then separately extracted. The numbers of pixels of each component are summed across obtained slices to create a ratio of visceral and subcutaneous fat to total fat. The percentage of visceral adipose tissue is then calculated.

Figure 4

(a) Axial gradient-echo fat-saturated three-dimensional MRI (repetition time (ms)/echo time (ms), 4.156/1.892; 4 mm thickness) of the abdomen at the level of the L3 vertebral body. (b) Visceral and (c) total fat components are highlighted. (d) Visceral and (e) total fat components are then extracted. The percentage of visceral adipose tissue is then calculated.