Compatibility of different methods for the measurement of visceral fat in different body mass index strata.

O besity is an important risk factor for diabetes mellitus, hypertension, hyperlipidemia, and cardiovascular disease (1); and is a strong predictor of increased morbidity and mortality (1, 2). Visceral adipose tissue accumulation, through increased fatty acid production, may be involved in the genesis of insulin resistance, creating a milieu for the development of these diseases (3, 4). Anthropometric measurements are often used as indirect measurements of visceral fat. Most widely used are waist circumference (WC) and waist-to-hip ratio (WHR). These measurement methods cannot differentiate between visceral fat tissue and subcutaneous fat tissue, but because their correlation with visceral fat tissue is quite good, they are often used as markers of visceral fat (5, 6). However, many trials have reported that such correlation was not applicable for all ages and BMI levels (7). The decreasing correlation is thought to reflect problems in anthropometric measurements in these populations, as these methods are subject to considerable between-examiner and within-examiner variation (5). Computed tomography (CT) has been considered the most accurate and reproducible technique of abdominal fat assessment (8). However, CT scans are costly and time-consuming and expose patients to ionizing radiation. Because of these limitations, a variety of alternative methods to assess fat distribution and estimate intra-abdominal fat deposition have been developed (5). Magnetic resonance imaging (MRI) yielded excellent concordance with CT without radiation exposure but was more expensive than CT (9). Ultrasonography (US) may be another alternative to CT for estimation of visceral fat tissue (10). Bioelectrical impedance analysis (BIA) measures visceral fat tissue using bipolar or tetrapolar electrodes on the legs and sometimes on the arms (11). Bioelectrical impedance analysis may be a good alternative because it does not expose the patient to radiation and is not time consuming. However, several body-composition characteristics, such as hydration and edema, may affect the validity of the interpretation of impedance measurements, particularly in morbidly obese patients; thus use of BIA is still controversial (11). Although anthropometric methods are frequently used today, they are inadequate for predicting cardiovascular risk increase, particularly in non-obese individuals. Therefore, search for convenience in clinical practice, low cost, and appropriate visceral fat tissue measurement methods are ongoing. This study aimed to compare methods for assessment of abdominal fat distribution, particularly visceral fat deposition, in different body mass index strata as alternatives to CT.