Ultrasound measurement of total body fat in obese adolescents

To compare body fat (BF) measurements obtained with a new ultrasound method with those assessed by dual-energy X-ray absorptiometry (DEXA) in obese adolescents.

In 94 adolescents (57 females and 37 males) aged 12-19 years and body mass index (BMI) exceeding 30 kg.m(-2), the z-score BMI for age was 6.7 (adolescent girls) and 6.6 (adolescent boys) >97th percentile. BF was measured using DEXA and a method based on ultrasound measurements, body weight, height, abdominal circumference and mid-thigh circumference.

Obesity class I was noted in 39%, II in 28% and III in 33% of the patients. BF by ultrasound correlated closely with BF by DEXA, in both females (r = 0.958) and males (r = 0.981), with standard errors of the estimates (SEE) being 2.9 and 2.5 kg, respectively. The ultrasound method was more accurate than the skinfold technique (n = 24; SEE: 2.2 vs. 6.5 kg, respectively). In 13 adolescents who had marked weight loss after 6 months of treatment, the decrease in DEXA-measured BF correlated closely with the decrease in ultrasound-measured BF (r = 0.95).

Our innovative portable ultrasound technique has advantages in terms of reliability, reproducibility, accuracy and costs for screening and monitoring obese adolescents. A patent application has been submitted. Our method should prove valuable for epidemiological studies.