**4.3 Relationship between BMI and WC**

Regarding the knowledge produced about the use of BMI or WC to assess the pattern of body fat, scholars of the subject in search of an answer demonstrated that there is a strong correlation coefficient between both measures, indicating that the waist circumference can determine, satisfactorily, children with high BMI [6, 7]. Investigations found important correlation values between BMI and WC, suggesting the joint use for the diagnosis of obesity, overweight, and central obesity [6], including in children and adolescents [7, 8].

BMI expresses changes that may occur in the distribution of fat, but does not verify the pattern of body fat. Thus, correlating this measure with other anthropometric measures is necessary, considering that the type of deposit of fat distribution is related to the health prognosis. However, WC is the measure that best represents the distribution of visceral fat and this, in turn, is more related to metabolic changes than subcutaneous fat, indicating the risk of children or adolescents to develop cardiovascular disease in future life. In addition, the relationship of this anthropometric measure with dyslipidemia, with arterial hypertension, and with the metabolic syndrome is evidenced in the literature and, therefore, should support professional practice [6].

McCarthy et al. stated that BMI may be a less sensitive indicator of fat among children and does not provide any indication of fat distribution. Information about WC in children can be as useful as BMI in population studies [39].

WC can be adopted as an alternative or additional measure to BMI in children. It is a direct measure that requires simple and inexpensive equipment, with the registration of a single value. BMI requires more complex equipment and mathematical calculations [39].

Researchers stressed the difference between ethnic groups and the importance of developing specific population patterns, as visceral adiposity is highly variable in children and is related to ethnicity [39]. The relative distribution of intra-abdominal tissue in relation to the subcutaneous abdominal region is significantly less in African American children than in whites [40].

For the same BMI, there may be individuals with more or less cardiovascular and metabolic risk, depending on the amount of intra-abdominal fat, which is also true for children [41]. It was shown that 23.4% of eutrophic children by BMI had high waist circumference [7].

#### **4.4 Other anthropometric measurements**

The waist-hip ratio and sagittal diameter are methods that indirectly determine visceral fat [28], predicting cardiovascular risk [38]. These anthropometric measures are methods used to assess body adiposity; however, they are unable to differentiate visceral from subcutaneous fat and have relatively high intra- and inter-examiner variability [29].

The assessment of adiposity through skinfold measurements is poorly reproducible and its usefulness in clinical practice is limited [15].

#### **5. Diagnosis by imaging exams**

Imaging exams are the methods of choice to assess and quantify visceral fat, since anthropometric measurements are unable to differentiate intra-abdominal from subcutaneous fat, as they are indirect measures [2, 29].

Dual-energy X-ray absorptiometry (DXA), a "scanning" technique considered to be reliable, whose mechanism occurs through two X-ray beams that cross the body, is used for the evaluation of the total and regional body composition of lean mass, fat mass, and bone mineral density. However, in the case of children, although it is a reference method, radiation exposure and high cost must be considered [6, 36].

Studies that concluded that anthropometric measurements have a strong correlation with the fat distribution indicated by DXA [6, 42] stand out. DXA estimates abdominal adiposity, but does not specifically quantify intra-abdominal fat [43].

Computed tomography (CT) is the gold standard method for the determination of visceral abdominal fat (VAF), due to its ability to differentiate between subcutaneous and visceral adiposity [44]. CT has the advantage of not depending on the operator's ability to identify structures during the examination and not be influenced by ultrasound transducer pressure on the abdomen during measurements. However, CT is an expensive method and submits patients to ionizing radiation, which limits its use mainly in epidemiological studies [31, 44].

Full-body CT measurements are accompanied by high radiation exposure and; therefore, they are not recommended for scientific purposes in healthy individuals. Thus, CT had to be restricted to some characteristic slices in most studies [36].

Magnetic resonance imaging (MRI) has also developed criteria for assessing visceral fat, with good accuracy [29, 44]; it is a method with which it is possible to assess the distribution of adipose tissue in children [10]. This test has the advantage of not emitting ionizing radiation [36] and the ability to quantify the fraction of fat [10]; however, it is more subject to artifacts than CT [29]. In addition, due to the high cost, greater need for sedation, and its limitation in claustrophobic patients, MRI has not been used routinely [10]. Among the limitations of the method for young children, there is the need to remain completely immobile during image capture [45].

Ultrasonography, in recent years, has been proposed as a noninvasive technique for the assessment of intra-abdominal fat [43], as it is a useful method for the

**93**

*Diagnostic Methods in Childhood Obesity DOI: http://dx.doi.org/10.5772/intechopen.92880*

such as population screening [10].

a sensitivity of up to 90% [36].

population, stands out.

computed tomography [29].

in BMI [20].

**6. Conclusions**

be the only morbidity.

cardiovascular disease among young adults.

evolutionary monitoring of obesity treatments.

as a treatment control in individual cases [29].

determination of visceral adipose tissue [28, 44]. The possibility of measuring visceral fat attributes to US an important role in the assessment of MS [29].

Ultrasonography appears as one of the methods of diagnosis and characterization of abdominal fat, allowing the correlation of its findings with data from anthropometric physical examination in all age groups, being of great value in the

In addition to measuring abdominal fat thickness, the method assesses the presence of liver fat. While some authors describe a sensitivity of ultrasonography in mode B for the detection of hepatic steatosis of just over 60%, other authors report

Among its advantages, the ability to differentiate accumulation of intraperitoneal, pre-peritoneal, and subcutaneous fats, in addition to the safety of the examination, practicality, and speed, especially in the evaluation of the pediatric

US in children to measure pre-peritoneal fat and intra-peritoneal fat is a valid method for epidemiological and clinical studies [20, 46]. Statistical significance was observed between the thickness of intra-abdominal fat and subcutaneous tissue in relation to obesity in children [20]. US can be useful in measuring intraperitoneal fat in children and adolescents [20, 47]. The thickness of the subcutaneous fat showed no statistically significant difference between the sexes, between the age groups and in relation to the presence or not of steatosis. However, US can be used

The ultrasound technique consists of measuring the thickness of the subcutaneous and visceral abdominal fat, separately, using a transducer placed 1 cm (cm) above the umbilical scar. The thickness of the visceral adipose tissue obtained with this technique has a good correlation with the area of that same tissue quantified by

The knowledge acquired can be useful to employ a new method of assessing visceral fat and also to seek ultrasound parameters that change with the increase

The techniques must be accurate and suitable for use both at the cross-sectional level (i.e., a single measure) and for monitoring the effects of interventions (behav-

Considering that the first signs and symptoms of obesity and its consequences can be determined in childhood, it becomes evident the importance of assessing subcutaneous and visceral fats in children, a population in which obesity may still

The pediatric detection and control of intra-abdominal obesity are important because it is associated with the metabolic syndrome in childhood, adolescence, and adulthood, and its progression can increase rates of morbidity and mortality due to

ioral, pharmacological, and surgical) aimed at promoting a healthy life [45].

In contrast to the disadvantages of CT, MRI, and anthropometric measurements, US has been establishing a simple, low-cost method, without radiation risk [29], free of side effects [10], with reproducibility and reliability already proven in the quantification of visceral fat [29], despite the need for specific equipment and welltrained observers, which can be repeated when necessary [28] and on a large scale,

#### *Diagnostic Methods in Childhood Obesity DOI: http://dx.doi.org/10.5772/intechopen.92880*

*Weight Management*

waist circumference [7].

inter-examiner variability [29].

**5. Diagnosis by imaging exams**

African American children than in whites [40].

**4.4 Other anthropometric measurements**

ible and its usefulness in clinical practice is limited [15].

from subcutaneous fat, as they are indirect measures [2, 29].

which limits its use mainly in epidemiological studies [31, 44].

children and is related to ethnicity [39]. The relative distribution of intra-abdominal tissue in relation to the subcutaneous abdominal region is significantly less in

The waist-hip ratio and sagittal diameter are methods that indirectly determine visceral fat [28], predicting cardiovascular risk [38]. These anthropometric measures are methods used to assess body adiposity; however, they are unable to differentiate visceral from subcutaneous fat and have relatively high intra- and

The assessment of adiposity through skinfold measurements is poorly reproduc-

Imaging exams are the methods of choice to assess and quantify visceral fat, since anthropometric measurements are unable to differentiate intra-abdominal

Dual-energy X-ray absorptiometry (DXA), a "scanning" technique considered to be reliable, whose mechanism occurs through two X-ray beams that cross the body, is used for the evaluation of the total and regional body composition of lean mass, fat mass, and bone mineral density. However, in the case of children, although it is a reference method, radiation exposure and high cost must be considered [6, 36]. Studies that concluded that anthropometric measurements have a strong correlation with the fat distribution indicated by DXA [6, 42] stand out. DXA estimates abdominal adiposity, but does not specifically quantify intra-abdominal fat [43]. Computed tomography (CT) is the gold standard method for the determination of visceral abdominal fat (VAF), due to its ability to differentiate between subcutaneous and visceral adiposity [44]. CT has the advantage of not depending on the operator's ability to identify structures during the examination and not be influenced by ultrasound transducer pressure on the abdomen during measurements. However, CT is an expensive method and submits patients to ionizing radiation,

Full-body CT measurements are accompanied by high radiation exposure and; therefore, they are not recommended for scientific purposes in healthy individuals. Thus, CT had to be restricted to some characteristic slices in most studies [36]. Magnetic resonance imaging (MRI) has also developed criteria for assessing visceral fat, with good accuracy [29, 44]; it is a method with which it is possible to assess the distribution of adipose tissue in children [10]. This test has the advantage of not emitting ionizing radiation [36] and the ability to quantify the fraction of fat [10]; however, it is more subject to artifacts than CT [29]. In addition, due to the high cost, greater need for sedation, and its limitation in claustrophobic patients, MRI has not been used routinely [10]. Among the limitations of the method for young children,

there is the need to remain completely immobile during image capture [45].

for the assessment of intra-abdominal fat [43], as it is a useful method for the

Ultrasonography, in recent years, has been proposed as a noninvasive technique

For the same BMI, there may be individuals with more or less cardiovascular and metabolic risk, depending on the amount of intra-abdominal fat, which is also true for children [41]. It was shown that 23.4% of eutrophic children by BMI had high

**92**

determination of visceral adipose tissue [28, 44]. The possibility of measuring visceral fat attributes to US an important role in the assessment of MS [29].

In contrast to the disadvantages of CT, MRI, and anthropometric measurements, US has been establishing a simple, low-cost method, without radiation risk [29], free of side effects [10], with reproducibility and reliability already proven in the quantification of visceral fat [29], despite the need for specific equipment and welltrained observers, which can be repeated when necessary [28] and on a large scale, such as population screening [10].

Ultrasonography appears as one of the methods of diagnosis and characterization of abdominal fat, allowing the correlation of its findings with data from anthropometric physical examination in all age groups, being of great value in the evolutionary monitoring of obesity treatments.

In addition to measuring abdominal fat thickness, the method assesses the presence of liver fat. While some authors describe a sensitivity of ultrasonography in mode B for the detection of hepatic steatosis of just over 60%, other authors report a sensitivity of up to 90% [36].

Among its advantages, the ability to differentiate accumulation of intraperitoneal, pre-peritoneal, and subcutaneous fats, in addition to the safety of the examination, practicality, and speed, especially in the evaluation of the pediatric population, stands out.

US in children to measure pre-peritoneal fat and intra-peritoneal fat is a valid method for epidemiological and clinical studies [20, 46]. Statistical significance was observed between the thickness of intra-abdominal fat and subcutaneous tissue in relation to obesity in children [20]. US can be useful in measuring intraperitoneal fat in children and adolescents [20, 47]. The thickness of the subcutaneous fat showed no statistically significant difference between the sexes, between the age groups and in relation to the presence or not of steatosis. However, US can be used as a treatment control in individual cases [29].

The ultrasound technique consists of measuring the thickness of the subcutaneous and visceral abdominal fat, separately, using a transducer placed 1 cm (cm) above the umbilical scar. The thickness of the visceral adipose tissue obtained with this technique has a good correlation with the area of that same tissue quantified by computed tomography [29].

The knowledge acquired can be useful to employ a new method of assessing visceral fat and also to seek ultrasound parameters that change with the increase in BMI [20].

The techniques must be accurate and suitable for use both at the cross-sectional level (i.e., a single measure) and for monitoring the effects of interventions (behavioral, pharmacological, and surgical) aimed at promoting a healthy life [45].

#### **6. Conclusions**

Considering that the first signs and symptoms of obesity and its consequences can be determined in childhood, it becomes evident the importance of assessing subcutaneous and visceral fats in children, a population in which obesity may still be the only morbidity.

The pediatric detection and control of intra-abdominal obesity are important because it is associated with the metabolic syndrome in childhood, adolescence, and adulthood, and its progression can increase rates of morbidity and mortality due to cardiovascular disease among young adults.

Therefore, this population should be the target of prevention policies and programs, early diagnosis, and medical-nutritional monitoring, aiming to identify the risks of these pathologies and their health consequences.
