Subcutaneous Adipose Tissue Measured by B-Mode Ultrasound to Assess and Monitor Obesity and Cardio-Metabolic Risk in Children and Adolescents.

Monitoring of children at heightened risk of cardio-metabolic diseases raises the need for accurate assessment of obesity. A standardized approach for measuring subcutaneous adipose tissue (SAT) by bright-mode ultrasound was evaluated in relation to body indices and anthropometry in a cross-sectional sample of 76 South African children (7-10 years) and 86 adolescents (13-17 years) to assess cardio-metabolic risk. SAT was higher in girls as compared to boys (children: 50.0 ± 21.7 mm > 34.42 ± 15.8 mm, adolescents: 140.9 ± 59.4 mm > 79.5 ± 75.6 mm, p < 0.001) and up to four times higher in adolescents than in children. In children, measures of relative body weight showed only a poor correlation to SAT (BMI: r = 0.607, p < 0.001), while in adolescents, BMI correlated high with SAT (r = 0.906, p < 0.001) based on high rates of overweight and obesity (41.8%). Children with identical BMIs may have large differences (>2-3-fold) in their amount of SAT. The moderate association to systolic (r = 0.534, r = 0.550, p < 0.001) and diastolic blood pressure (r = 0.402, r = 0.262, p < 0.001) further substantiates that SAT measured by ultrasound provides an accurate, safe and easy applicable approach for monitoring in children and adolescents at cardio-metabolic risk.

Hypercarotenemia in Anorexia Nervosa Patients May Influence Weight Balance: Results of a Clinical Cross-Sectional Cohort Study.

Introduction: Anorexia nervosa (AN) can co-occur with hypercarotenemia, a clinical condition characterized by elevated ß-carotene in plasma and skin tissue. Carotenoids have known anti-obesogenic effects in adipocyte biology. Thus, carotenoids may potentially play a retarding role in weight gain during the recovery of AN patients. This study evaluated the plasma carotenoid profile and subcutaneous adipose tissue (SAT) in a cohort of AN patients and normal weight (NW) controls. Methods: Plasma concentrations of α-carotene, ß-carotene, ß-cryptoxanthin, and lycopene were determined by HPLC analysis. SAT thicknesses were measured by a highly accurate and reliable ultrasound technique. Information on dietary intakes were collected by repeated 24-h recalls. Results: Sixty-two females (AN: n = 18, NW: n = 44) were included. The concentrations of ß-cryptoxanthin (p = 0.045) and lycopene (p = 0.004) were significantly lower in AN patients. ß-carotene levels were higher in AN patients (n.s.) and α-carotene did not differ significantly. SAT thickness was significantly lower in AN patients compared to controls (p < 0.001). ß-carotene was significantly negative (r s = -0.471) and lycopene significantly positive (r s = 0.366) correlated with SAT. The correlation of ß-carotene and SAT was even higher in the AN group alone (r s = -0.742). Also, ß- cryptoxanthin and the sum of provitamin A carotenoids were correlated to SAT (r s = -0.647 and r s = -0.746, respectively) in AN patients. Fruits and vegetable intake did not differ significantly between AN and NW but adjusted for SAT, AN patients consumed relatively higher amounts (p = 0.006). Conclusion: Higher plasma ß-carotene concentrations were associated with reduced SAT levels, most probably due to a reduced ability of the remaining adipose tissue to store carotenoids. Thus, the antiobesity effects of carotenoids might impact the treatment success of undernutrition and AN. A systemic carotenoid overload may contribute to changes in adipogenesis and metabolic capacities for energy storage. Therefore, high plasma ß-carotene may be a marker of delay in weight recovery in AN patients. Interventional studies should consider including carotenoid-status in AN treatment.

Competitive Performance of Kenyan Runners Compared to their Relative Body Weight and Fat.

Body fat values obtained with various measurement methods deviate substantially in many cases. The standardised brightness-mode ultrasound method was used in 32 Kenyan elite long-distance runners to measure subcutaneous adipose tissue thicknesses at an accuracy and reliability level not reached by any other method. Subcutaneous adipose tissue forms the dominating part of body fat. Additionally, body mass (m), height (h), sitting height (s), leg length, and the mass index MI1 =0.53m/(hs) were determined. MI1 considers leg length, which the body mass index ignores. MI1 values of all participants were higher than their body mass indices. Both indices for relative body weight were within narrow ranges, although thickness sums of subcutaneous adipose tissue deviated strongly (women: 20-82 mm; men: 3-36 mm). Men had 2.1 times more embedded fasciae in the subcutaneous adipose tissue. In the subgroup with personal best times below world record time plus 10%, no correlation between performance and body mass index was found, and there was also no correlation with sums of subcutaneous adipose tissue thicknesses. Within the data ranges found here, extremely low relative body weight or low body fat were no criteria for the level of performance, therefore, pressure towards too low values may be disadvantageous.

Relative Body Weight and Standardised Brightness-Mode Ultrasound Measurement of Subcutaneous Fat in Athletes: An International Multicentre Reliability Study, Under the Auspices of the IOC Medical Commission.

INTRODUCTION: Fat is a metabolic fuel, but excess body fat is ballast mass, and therefore, many elite athletes reduce body fat to dangerously low levels. Uncompressed subcutaneous adipose tissue (SAT) thickness measured by brightness-mode ultrasound (US) provides an estimate of body fat content. METHODS: The accuracy for determining tissue borders is about 0.1-0.2 mm and reliability (experienced measurers) was within ± 1.4 mm (95% limit of agreement, LOA). We present here inter- and intra-measurer scores of three experienced US measurers from each of the centres C1 and C2, and of three novice measurers from each of the centres C3-C5. Each of the five centres measured 16 competitive adult athletes of national or international level, except for one centre where the number was 12. The following sports were included: artistic gymnastics, judo, pentathlon, power lifting, rowing, kayak, soccer, tennis, rugby, basketball, field hockey, water polo, volleyball, American football, triathlon, swimming, cycling, long-distance running, mid-distance running, hurdles, cross-country skiing, snowboarding, and ice hockey. SAT contour was detected semi-automatically: typically, 100 thicknesses of SAT at a given site (i.e., in a given image), with and without fibrous structures, were measured. RESULTS: At SAT thickness sums DI (of eight standardised sites) between 6.0 and 70.0 mm, the LOA of experienced measurers was 1.2 mm, and the intra-class correlation coefficient ICC was 0.998; novice measurers: 3.1 mm and 0.988. Intra-measurer differences were similar. The median DI value of all 39 female participants was 51 mm (11% fibrous structures) compared to 17 mm (18%) in the 37 male participants. DISCUSSION: DI measurement accuracy and precision enables detection of fat mass changes of approximately 0.2 kg. Such reliability has not been reached with any other method. Although females' median body mass index and mass index were lower than those of males, females' median DI was three times higher, and their percentage of fibrous structures was lower. The standardised US method provides a highly accurate and reliable tool for measuring SAT and thus changes in body fat, but training of measurers is important.

Novel approaches for the assessment of relative body weight and body fat in diagnosis and treatment of anorexia nervosa: A cross-sectional study.

BACKGROUND & AIMS: Anorexia nervosa (AN) is a severe psychosomatic disease that seriously affects nutritional status. Therapeutic approaches primarily aim for rapid weight restoration by high caloric diets and activity restriction. This often promotes abdominal body fat gain, which potentially negatively influences the patient's compliance and increases the risk of relapse. This study focused on the evaluation of body weight and subcutaneous adipose tissue (SAT) in AN patients by novel approaches. METHODS: The SAT of AN patients (n = 18, body mass index (BMI) 15.3 ± 1.3 kg/m2) was determined by a highly accurate and reliable ultrasound method. The sum of SAT thicknesses of eight sites (DINCL) was calculated. Individual metabolic profiles were analyzed. The mass index (MI), which considers body proportions, was used in addition to BMI. Additional to the standard laboratory diagnostics, dermal carotenoids measured by resonance Raman spectroscopy, leptin, and oxidative stress indicators were determined. RESULTS: The mean MI was 15.7 ± 1.4 kg/m2. The DINCL considerably differed between individuals with the same BMI. Half of the patients (Group 1) had low DINCL: 1.3-28.4 mm, and Group 2 showed values up to 58.2 mm (corresponding to approximately 6 kg SAT mass). The two group means differed by more than 300% (P < 0.001). Accordingly, leptin levels significantly differed (P < 0.001). Mean SAT thicknesses were significantly higher in Group 2 at all eight sites. The groups also significantly differed in two oxidative stress parameters: total antioxidative capacity, malondialdehyde-modified low density lipoprotein immunoglobulin M (MDA-LDL IgM), and in the carotenoid level. CONCLUSION: Half of the patients had sufficiently high fat mass, despite very low BMI. Consequently, their muscle (and other organ) masses must have been extremely low. Diagnostic criteria and treatment protocols for AN should consider each patient's body composition. In addition to dietary treatments, muscle training at low energy turnover rates may be essential for avoiding unnecessary body fat gain, better treatment results, and long-term recovery.

Measurement of mean subcutaneous fat thickness: eight standardised ultrasound sites compared to 216 randomly selected sites.

Ultrasound (US) provides the most accurate technique for thickness measurements of subcutaneous adipose tissue (SAT) layers. This US method was recently standardised using eight sites to capture SAT patterning and allows distinguishing between fat and embedded fibrous structures. These eight sites chosen for fat patterning studies do not represent the mean SAT thickness measured all over the body that is necessary for determining subcutaneous fat mass. This was obtained by SAT measurements at 216 sites distributed randomly all over the body. Ten participants with BMI below 28.5kgm-2 and SAT means (from eight sites) ranging from 3 mm to 10 mm were selected. The means from eight sites overestimated the means obtained from 216 sites (i.e. 2160 US measurements in the ten participants); the calibration factor of 0.65 corrects this; standard deviation (SD) was 0.05, i.e. 8%. The SD of the calibration factor transforms linearly when estimating the error range of the whole body's SAT volume (body surface area times the calibrated mean SAT thickness). The SAT masses ranged from 3.2 to 12.4 kg in this group. The standard deviations resulting from solely the calibration factor uncertainty were ±0.3 and ±1.0 kg, respectively. For these examples, the SAT percentages were 4.9(±0.4)% and 13.3(±1.0)%.

Standardized Ultrasound Measurement of Subcutaneous Fat Patterning: High Reliability and Accuracy in Groups Ranging from Lean to Obese.

A recently standardized ultrasound technique for measuring subcutaneous adipose tissue (SAT) was applied to normal-weight, overweight and obese persons. Eight measurement sites were used: upper abdomen, lower abdomen, erector spinae, distal triceps, brachioradialis, lateral thigh, front thigh and medial calf. Fat compression was avoided. Fat patterning in 38 participants (body mass index: 18.6-40.3 kgm-2; SAT thickness sums from eight sites: 12-245 mm) was evaluated using a software specifically designed for semi-automatic multiple thickness measurements in SAT (sound speed: 1450 m/s) that also quantifies embedded fibrous structures. With respect to ultrasound intra-observer results, the correlation coefficient ρ = 0.999 (p < 0.01), standard error of the estimate = 1.1 mm and 95% of measurements were within ±2.2 mm. For the normal-weight subgroup, the median measurement deviation was 0.43 mm (1.1% of mean thickness), and for the obese/overweight subgroup it was 0.89 mm (0.5%). The eight sites used here are suggested to represent inter-individual differences in SAT patterning. High measurement accuracy and reliability can be obtained in all groups, from lean to overweight and obese, provided that measurers are trained appropriately.

Subcutaneous fat patterning in athletes: selection of appropriate sites and standardisation of a novel ultrasound measurement technique: ad hoc working group on body composition, health and performance, under the auspices of the IOC Medical Commission.

BACKGROUND: Precise and accurate field methods for body composition analyses in athletes are needed urgently. AIM: Standardisation of a novel ultrasound (US) technique for accurate and reliable measurement of subcutaneous adipose tissue (SAT). METHODS: Three observers captured US images of uncompressed SAT in 12 athletes and applied a semiautomatic evaluation algorithm for multiple SAT measurements. RESULTS: Eight new sites are recommended: upper abdomen, lower abdomen, erector spinae, distal triceps, brachioradialis, lateral thigh, front thigh, medial calf. Obtainable accuracy was 0.2 mm (18 MHz probe; speed of sound: 1450 m/s). Reliability of SAT thickness sums (N=36): R(2)=0.998, SEE=0.55 mm, ICC (95% CI) 0.998 (0.994 to 0.999); observer differences from their mean: 95% of the SAT thickness sums were within ± 1 mm (sums of SAT thicknesses ranged from 10 to 50 mm). Embedded fibrous tissues were also measured. CONCLUSIONS: A minimum of eight sites is suggested to accommodate inter-individual differences in SAT patterning. All sites overlie muscle with a clearly visible fascia, which eases the acquisition of clear images and the marking of these sites takes only a few minutes. This US method reaches the fundamental accuracy and precision limits for SAT measurements given by tissue plasticity and furrowed borders, provided the measurers are trained appropriately.

Body composition in sport: a comparison of a novel ultrasound imaging technique to measure subcutaneous fat tissue compared with skinfold measurement.

BACKGROUND: Extremely low weight and rapid changes in weight and body composition have become major concerns in many sports, but sufficiently accurate field methods for body composition assessment in athletes are missing. This study aimed to explore the use of ultrasound methods for assessment of body fat content in athletes. METHODS: 19 female athletes (stature: 1.67(± 0.06) m, weight: 59.6(± 7.6) kg; age: 19.5(± 3.3) years) were investigated by three observers using a novel ultrasound method for thickness measurement of uncompressed subcutaneous adipose tissue and of embedded structures. Two observers also measured skinfold thickness at eight International Society for the Advancement of Kinanthrometry (ISAK) sites; mean skinfold values were compared to mean subcutaneous adipose tissue thicknesses measured by ultrasound. Interobserver reliability of imaging and evaluation obtained by this ultrasound technique: intraclass correlation coefficient ICC=0.968 (95% CI 0.957 to 0.977); evaluation of given images: ICC=0.997 (0.993 to 0.999). RESULTS: Skinfold compared to ultrasound thickness showed that compressibility of subcutaneous adipose tissue depends largely on the site and the person: regression slopes ranged from 0.61 (biceps) to 1.59 (thigh) and CIs were large. Limits of agreement ranged from 2.6 to 8.6 mm. Regression lines did not intercept the skinfold axis at zero because of the skin thickness being included in the skinfold. The four ISAK trunk sites caused ultrasound imaging problems in 13 of 152 sites (8 ISAK sites, 19 athletes). CONCLUSIONS: The ultrasound method allows measurement of uncompressed subcutaneous adipose tissue thickness with an accuracy of 0.1-0.5 mm, depending on the probe frequency. Compressibility of the skinfold depends on the anatomical site, and skin thickness varies by a factor of two. This inevitably limits the skinfold methods for body fat estimation. Ultrasound accuracy for subcutaneous adipose tissue measurement is limited by the plasticity of fat and furrowed tissue borders. Comparative US measurements show that skinfold measurements do not allow accurate assessment of subcutaneous adipose tissue thickness.

Body composition in sport: interobserver reliability of a novel ultrasound measure of subcutaneous fat tissue.

BACKGROUND: Very low body mass, extreme mass changes, and extremely low per cent body fat are becoming increasingly common in many sports, but sufficiently reliable and accurate field methods for body composition assessment in athletes are missing. METHODS: Nineteen female athletes were investigated (mean (SD) age: 19.5 (± 3.3) years; body mass: 59.6 (± 7.6) kg; height: 1.674 (± 0.056) m; BMI: 21.3 (± 2.3) kg/m(2)). Three observers applied diagnostic B-mode-ultrasound (US) combined with the evaluation software for subcutaneous adipose tissue measurements at eight ISAK sites (International Society for the Advancement of Kinanthrometry). Regression and reliability analyses are presented. RESULTS: US measurements and evaluation of subcutaneous adipose tissue (SAT) thicknesses (including fibrous structures: D(included); n=378) resulted in an SE of estimate SEE=0.60 mm, R(2)=0.98 (p<0.001), limit of agreement LOA=1.18, ICC=0.968 (0.957-0.977). Similar values were found for D(excluded): SEE=0.68 mm, R(2)=0.97 (p<0.001). D(included) at individual ISAK sites: at biceps, R(2)=0.87 and intraclass-correlation coefficient ICC=0.811 were lowest and SEE=0.79 mm was highest. Values at all other sites ranged from R(2): 0.94-0.99, SEE: 0.42-0.65 mm, and ICC: 0.917-0.985. Interobserver coefficients ranged from 0.92 to 0.99, except for biceps (0.74, 0.83 and 0.87). Evaluations of 20 randomly selected US images by three observers (D(included)) resulted in: SEE=0.15 mm, R(2)=0.998(p<0.001), ICC=0.997 (0.993, 0999). CONCLUSIONS: Subject to optimal choice of sites and certain standardisations, US can offer a highly reliable field method for measurement of uncompressed thickness of the SAT. High accuracy and high reliability of measurement, as obtained with this US approach, are essential for protection of the athlete's health and also for optimising performance.