Abstract

This methodological approach to assessing obesity is based on the prepilot work conducted on a small sample of men

and women (25-58 years of age) in a laboratory setting. The use of skinfold calipers, body mass index, and sonographic

imaging of adipose and visceral fat were obtained. In this pre-experimental work, the rigorous use of sonographic

measures of visceral fat demonstrated better trend results than the other measurement tools. The sonographic

methods employed were modeled after the work published by Hamagawa et al. All measurements were taken five

times, and only the middle three were retained for mean data points. The data are compared and contrasted with a

paucity of international studies using sonography to measure visceral adiposity. It is important to determine whether

sonography could serve as a non-ionizing imaging technique for the assessment of body composition and a screening

technique for cardiovascular disease prediction.

Keywords

visceral adiposity, ultrasonography, BMI, circumferences, metabolic syndrome, intra-abdominal fat, body composition

92 Journal of Diagnostic Medical Sonography 34(2)

and cardiovascular disease.13 The gold standard for quantitative

assessments of intra-abdominal adiposity is computed

tomography (CT) and magnetic resonance imaging

(MRI), but widespread utilization remains limited secondary

to accessibility and cost.14

Researchers have attempted to use diagnostic medical

sonography (DMS) to measure visceral fat layers;

however, most have documented limitations that were

related to low-frequency transducers and inconsistent

scanning protocols.15–17 A promising study, conducted

by Bazzocchi et al.,17 compared DMS measures to CT at

similar anatomical slices. If DMS were to be used to

measure intra-abdominal adiposity, the next step would

be to compare results with dual energy x-ray absorptiometry

(DXA). A DXA is a low-dose ionizing radiation

diagnostic scan that can be used as a measurement tool

for body fat.14,15 Comparing DXA to DMS for measuring

intra-abdominal adiposity would provide additional

validation as to the proper diagnostic tool that should be

used. The added value of using a non-ionizing technique

to screen for intra-abdominal adiposity and associated

cardiovascular disease risk could be important in translating

this diagnostic technique for patient assessment.

The American College of Radiology’s (ACR’s)

Appropriateness Criteria is an evidence-based tool that is

widely used to guide physicians and practitioners in making

appropriate recommendations for diagnostic testing. The

ACR recommendation for assessing risk in an asymptomatic

patient, at low risk for cardiovascular disease, is CT calcium

scoring; however, the rating is usually not appropriate.18

With a patient of intermediate risk, the rating for CT

increases to a rating of usually appropriate.18 The risk for

progressive metabolic disease is categorized differently, and

the ACR recommends a screening cardiac MRI with stress

and intravenous contrast.18 It would appear that less invasive

and reduced levels of ionizing radiation could be used to

screen patients at risk for progressive metabolic and cardiovascular

disease. The significance of providing a nonionizing

imaging technique for measuring abdominal visceral fat

has the potential to assist physicians and patients in making

proactive treatment decisions.

The utilization of DMS to measure abdominal visceral

fat would require more scientific evidence to raise the

ranking of this nonionizing technique and accelerate its

recommendation for screening high-risk patients. Given

the increasing rate of childhood obesity, it would also

seem important to promote a nonionizing imaging technique

for pediatric patients at risk for early development

of cardiovascular disease.

Literature Review

A Brazilian study was conducted with a cohort of 100

women who consented to an anthropometric evaluation

including bioelectrical impedance, DXA, DMS, and a CT

scan.19 In this research, the technique, descripted by

Bazzocchi et al.,17 was used to take abdominal visceral fat

measurements with modern DMS equipment. Multiple

measurements were taken, and an average was retained

across the data set. The CT evaluation of abdominal visceral

fat was selected as the gold standard, and all measurements

were compared for a possible non-ionizing

match. This study found that waist circumference, waistto-

hip ratio, and DMS measures of visceral fat were the

best correlated matches with values of visceral fat

detected by CT.19 In fact, a value of 6.90 cm of visceral

fat measured from a DMS image was deemed as an indicator

of visceral obesity and had a specificity of 82.8%, a

sensitivity of 69.2%, and correlated with CT at 74%.21

Given that this study was conducted on adult women with

a mean age of 50 years and limited range of obesity, a

larger group of subjects would provide more robust

evidence.

In previous studies, the same group of researchers

recruited a sample of 101 women who consented to DMS

for the purpose of assessing their abdominal visceral fat

and also with a CT scan.20 In this sample, clinical blood

biomarkers of cardiovascular risk were also obtained.

Again, the DMS image measurements of abdominal visceral

fat matched the CT images; however, they also were

moderately correlated with fasting insulin (r = 50.29 and

r = 50.27, P < .01) and plasma glucose 2 hours after oral

glucose load (r = 50.22 and r = 50.34, P < .05).18 The fasting

insulin was a clinical tool used to identify patients

with prediabetes. This study underscored the ability of

DMS image measurements to approach not only CT measurements

of abdominal visceral fat but also the predictive

ability that these measures could have compared to

CVD-specific biomarkers. Of note, one limitation was

the lack of specificity as to the DMS measure site. The

authors only described taking the measures “above the

umbilical knot.” For reproducibility, the measurements

taken from all imaging studies need specific landmarks.

Like the other study, this group of women had a mean age

of 50 years and were relatively homogeneous in terms of

anthropometry.18

In a large Chinese study, 4301 hypertensive inpatients

were recruited for a study using mixed assessments to

detect cardiovascular disease and visceral fat measures.21

The results documented that waist circumference was the

best predictor of a diagnosis of cardiovascular disease

followed by BMI, waist-to-hip ratio, bioelectrical impedance,

then intra-abdominal fat distance measured from

DMS, compared with CT.21 Because this study was published

in Chinese, the precise methods were difficult to

discern. Of interest is the cutoff values that they published

for both men and women based on their work. Since this

study was likely based on data from a convenient sample

Woldemariam et al. 93

of patients, it hampers the generalizability of the

findings.

To detect visceral adiposity and early stages of metabolic

and possible cardiovascular disease, a pilot study

was designed to determine whether the scanning and

sonographic measures stratifying subcutaneous and visceral

fat is relatively low cost, nonionizing, and

replicable.

Materials and Methods

A pilot study was completed in 2016 with a group of five

volunteers of mixed gender, age, weight, and adiposity.

For this study, a convenience sample of participants was

recruited from a university setting, via email. Prior to participation,

a short orientation was given to provide information

about the testing procedures and to obtain a verbal

consent. Data collected included a DMS scan, abdominal

skinfold, body weight, and height measurements.

Sonography

DMS uses high-frequency sound waves that penetrate the

skin surface and travel into body tissues, recording the

reflected signal.22 The GE Healthcare Logiq i (Milwaukee,

WI) ultrasound was used for this pilot. The transducer

selected as a 12-MHz linear that was upshifted to 16.0 MHz

and adjusted to an output power of 100% (MI: 0.13).

Acoustic gel was applied to the transducer, to reduce the loss

of acoustic power at the air-tissue interface. The transducer

was then placed perpendicular to the tissue interfaces.22

Participants were scanned using the protocol, described

by Hamagawa el al.23; however, this technique was

enhanced by using a cine loop of the sagittal area,

obtained from the xiphoid process to the umbilicus. Using

a cine loop, a scan in the sagittal plane facilitated the

measurement to be taken using the “run-stop” function,

retrospectively. An electronic caliper was used to measure

the subcutaneous fat thickness from skin (cutaneous

boundary) to the linea alba, and the visceral fat thickness

was measured from the peritoneum boundary to the linea

alba (Figure 1). Measurements were recorded and coded

as S min, referring to the subcutaneous fat measurement

taken at the narrowest point. V max was used to indicate

the visceral fat measured at two locations, close to the

xiphoid, and visceral fat was measured at the widest point

(Figure 2). The Hamagawa technique was used as a guide

in scanning, measuring, and recording data from the

sonographic images (Figure 1).

Abdominal Skinfold Measurement

Abdominal skinfold caliper measurements were taken on

the right side of the abdomen by a trained interventionist

using calibrated Lange calipers, about 1-inch lateral from

and 0.5 inches below the umbilicus. Each measurement

was taken five times, with the recorded score being the

median value of the five scores.24

BMI

A calibrated scale and a wall-mounted stadiometer were

used to take measurements of weight and height, respectively.

Weight (in pounds) was divided by height (in

inches) squared and multiplied by 703: BMI = (weight/

height)Ç) Å~ 703.

Results

DMS, BMI, and skinfold caliper measures of fat adipose

tissue were compared across the convenient sample of

three men and two women, ages 25 to 58 years. The data

collected were plotted such that the DMS measurement

Figure 1. The sonographic image documents the amount

of abdominal adipose tissue. Sonographic measurements of

thickened visceral fat are compared with subcutaneous fat.

Figure 2. The methodology of Hamagawa et al.23 for

capturing the sonographic image longitudinally and also

the anatomical landmarks for making the measurements.

Reproduced with permission from the author.

94 Journal of Diagnostic Medical Sonography 34(2)

of visceral body fat was compared with the other variables.

DMS measures of visceral fat and BMI tended to

trend more comparably than the skinfold measurements

(Table 1). DMS images are provided from the selected

subjects to demonstrate the data collected (Figures 1, 3,

and 4).

Graph 1 depicts the trending of the data as a result of

the data points collected.

Discussion

Because of increasing obesity and risk for cardiovascular

disease, this pilot points to the feasibility of DMS to measure

abdominal fat in a laboratory setting. Given that the

volunteers were a mix of men and women of varied age,

a study of a similar age range could help to fill in the

trend graph. Berker et al.25 recruited 104 participants, 19

to 58 years of age (men and women) as part of their study.

All subjects consented to anthropometric evaluation, bioelectrical

impedance analysis, DMS, and CT on the same

day. In this much larger study, they determined that the

most effective method for matching visceral fat on CT

was the visceral thickness measured with DMS, among

the male participants.25 In contrast, the best match for

Table 1. Comparison Between Measurements of Subcutaneous Fat, Visceral Fat, Body Mass Index (BMI), and Skinfold of Five

Participants.

Participant Gender Subfat Viscera Fat BMI BMI Category Skinfold

1 M 7.7 13.7 21.5 21.5 kg/m2 (18-25 normal) 37 mm

2 F 10.4 17.6 28.9 28.9 kg/m2 (25-29.9 overweight) 25.4 mm

3 M 9.7 16.5 25.3 25.3 kg/m2 (18-25 normal) 45 mm

4 F 3.9 10.3 17.4 17.4 kg/m2 (<18 underweight) 30 mm

5 M 5.8 11.5 21.2 21.2 kg/m2 (18-25 normal) 33 mm

Figure 3. Abdominal adipose tissue is imaged with both diagnostic medical sonography (DMS) (A) and computed tomography

(CT) (B). Measurement of DMS and CT adipose layers were imaged at comparable anatomical locations. Measurements were

taken at approximately the same level.

Figure 4. Transverse sonographic view of the upper

abdominal wall and the linea alba line, which compares

subcutaneous and visceral fat layers.

Woldemariam et al. 95

measurements of visceral fat in women was a combination

of measures with DMS, BMI, and waist circumference.

22 This would suggest that DMS could be used as a

nonionizing imaging technique for detecting visceral fat,

but due to the variety of anthropometrics among women,

it might be important to use mixed measurements.

The prevalence of childhood obesity is increasing at

an alarming rate. More than one-third of children are

overweight or obese.4,5 To provide screening of children

with a propensity for obesity and early cardiovascular

disease, a nonionizing imaging technique would be

important. It would also allow for quantifying visceral

obesity in pediatric patients given that BMI and skinfold

measurements are unreliable and CT imparts radiation

exposure. In a study of 73 pediatric patients, ages 7 to

13 years, biomarkers and visceral fat measurements

were obtained. Results of this study demonstrated a

strong positive correlation between DMS measures of

visceral fat and categories of obesity. DMS measures of

visceral fat were moderately correlated with a homeostasis

model assessment for insulin resistance score (r =

0.403, P < .001).26

This pilot is innovative as it applied high-frequency

transducers to obtain the highest level of resolution and

additionally demonstrates feasibility that this measurement

technique can be further tested for both accuracy

and reliability. As mentioned earlier, clinicians are

encouraged to use BMI and waist circumference for

assessing obesity in adults and children.11,12 This pilot

study would suggest that DMS measures could be a possible

tool that would provide more global data to that

assessment.

In addition, as a nonionizing imaging technique, this is

a tool that could be expanded to address the United States

Department of Agriculture’s childhood obesity prevention

strategies as a safe and accessible tool for quantifying

visceral adiposity and predicting risk of obesity-related

disease.27 Sonographic techniques have tremendous

potential as a screening tool; however, prospective studies

that adopt this sonographic technique should adhere to

the current evidence promoting inclusion of a battery of

biomarkers to ensure maximum effectiveness. In summary,

these early findings support the feasibility of DMS

to measure abdominal fat in a clinical or community setting,

particularly in pediatric populations.

Acknowledgments

The research team would like to thank The Ohio State

University’s Clinical Research Center staff. The dedicated staff

and graduate students make this ongoing research possible as

well as provide valuable assistance to these patients.

Declaration of Conflicting Interests

The authors declared no potential conflicts of interest with

respect to the research, authorship, and/or publication of this

article.

Funding

The authors received no financial support for the research,

authorship, and/or publication of this article.

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