Jonathan Tresignie

Assessment of regional adipose tissue depots: A DXA and CT comparison in cadavers of elderly persons

OBJECTIVE Since dual energy X-ray absorptiometry (DXA) cannot distinguish between different adipose tissue (AT) deposits, it remains unclear how DXA-derived body composition variables relate to anatomical tissue (sub)compartments. The aim of the present study was to compare and relate regional DXA variables with absolute tissue masses obtained by computer tomography (CT) scanning of the lower limbs in elderly persons. METHODS Eleven well-preserved white Caucasian adults (seven male and four female cadavers) with a median age of 79.0 years (ranging from 68 to 96 years) were fully scanned with DXA and CT. Separate densities of skin tissue, AT, muscle tissue and bone were obtained by hydrostatic weighing. RESULTS The leg DXA-variables were significantly related (rho-values between 0.60 and 0.98, P < 0.01) to CT-derived tissue counterparts, but showed significant systematic differences except for subcutaneous AT mass (P = 0.773). After controlling for other AT depots, fat as measured by DXA (fat(DXA)) related only to intermuscular AT (rho = 0.82, P < 0.01) in males and to subcutaneous AT (rho = 0.84, P < 0.05) in females. CONCLUSION Although significantly interrelated, DXA and CT variables should not be used interchangeably since they have different quantitative and physiological significance. Our results suggest that fat(DXA) represents different parts of AT depots in elderly men and women. Since DXA is not appropriate for assessing tissue variability cautious clinical interpretation is warranted.

Prediction of segmental lean mass using anthropometric variables in young adults

Abstract The aim of the present study was to develop and cross-validate anthropometrical prediction equations for segmental lean tissue mass (SLM). One hundred and seventeen young healthy Caucasians (67 men and 50 women; mean age: 31.9 ± 10.0 years; Body Mass Index: 24.3 ± 3.2 kg · m−2) were included. Body mass (BM), stretch stature (SS), 14 circumferences (CC), 13 skinfolds (SF) and 4 bone breadths (BB) were used as anthropometric measurements. Segmental lean mass of both arms, trunk and both legs were measured by dual energy X-ray absorptiometry as the criterion method. Three prediction equations for SLM were developed as follows: arms = 40.394(BM) + 169.836(CCarm-tensed) + 399.162(CCwrist) – 85.414(SFtriceps) – 39.790(SFbiceps) – 7289.190, where Adj.R 2 = 0.97, P < 0.001, and standard error of estimate (SEE) = 355 g;trunk = 181.530(BM) + 155.037(SS) + 534.818(CCneck) + 175.638(CCchest) − 88.359(SFchest) − 147.232(SFsupraspinale) − 46522.165, where Adj.R 2 = 0.97, P < 0.001, and SEE = 1077g; and legs = 55.838(BM) + 88.356(SS) + 235.579(CCmid-thigh) + 278.595(CCcalf) + 288.984(CCankle) − 84.954(SFfront-thigh) − 53.009(SFmedial calf) − 28522.241, where Adj.R 2 = 0.96, P < 0.001, and SEE = 724 g. Cross-validation statistics showed no significant differences (P < 0.05) between observed and predicted SLM. Root mean squared errors were smallest for arms (362 g), followed by legs (820 g) and trunk (1477 g). These new prediction equations allow an accurate estimation of segmental lean mass in groups of young adults, but estimation errors of 8 to 14% can occur in certain individuals.

Reproducibility, accuracy and concordance of Accutrend® Plus for measuring circulating lipid concentration in adults

Introduction The determination of lipid biomarkers by capillary sampling may be useful in the screening, diagnosis and/or personal management of hyperlipidemia and cardiovascular risk. It remains unclear whether the use of the Accutrend® Plus system is appropriate. This study aimed to assess its reproducibility, accuracy and concordance for blood lipid profiling in adults. Materials and methods: Fasting capillary total cholesterol (TC) and triglyceride (TG) concentration on Accutrend® Plus were compared with their venous analogues obtained by a laboratory reference method in sixty-one adults (27 men and 34 women, aged 33.0 years). Supplementary capillary sampling was performed at two consecutive days taking into account macro-nutrient intake. Results: The day-to-day reproducibility of the Accutrend® Plus system proved to be high for TC (ICC = 0.85, P < 0.001), but moderate for TG (ICC = 0.68, P < 0.001). Strong correlations (r ≥ 0.80, P < 0.001) with the reference method were found for TC and TG. Mean difference (limits of agreement) were: 0.26 mmol/L (−0.95, 1.47) for TC, and −0.16 mmol/L (−1.29, 0.98) for TG. The concordance for subject classification according to the National Cholesterol Education Program (NCEP) guidelines was significant (P < 0.001), with substantial agreement for TC (κw = 0.67), and moderate agreement for TG (κw = 0.50). Conclusions: Day-to-day reproducibility of the Accutrend® Plus device for TC and TG is not optimal and lacks accuracy when compared to the reference laboratory method. The concordance between both methods for classifying subjects according to the NCEP is inadequate. Accutrend® Plus device should not be interchangeably used as a substitution for the standard laboratory methods in the diagnosis of hyperlipidemia.

Whole Body Composition by Hologic QDR 4500/A DXA: System Reliability versus User Accuracy and Precision

Accurate and precise measurement of human tissue composition is both important and imperative in individual health assessment. Although body composition (BC) data acquisition and analysis are both popular and important, selecting an appropriate method or technique for accurate and/or precise assessment of individuals and/or groups remains a challenging task within various sectors of public health. Since 1950s and 1960s, with the pioneer work of Keys & Brozek (1953), Forbes et al. (1956), Siri (1956), Brozek et al. (1963), Behnke (1963), Durnin & Rahaman (1967), BC almost became a scientific discipline profiling itself with the development of many methods, techniques, and equipments. Popular approaches have been criticized over the years because they are subject to measurement errors and/or violation of basic assumptions underlying their use such as hydrodensitometry (Clarys et al., 2010c; Clasey et al., 1999; Elowsson et al., 1998; Heyward, 1996; Johansson et al., 1993; Prior et al., 1997) or anthropometry, e.g., skinfolds (Beddoe, 1998; Clarys et al., 1987, 2005, 2010a; Martin et al., 1985, 1992; Scafoglieri et al., 2010a) and the universally accepted new method of choice, the dual energy X-ray absorptiometry (DXA) (Bolotin, 1998, 2007; Bolotin & Sievanen, 2001; Bolotin et al., 2001; Clarys et al., 2010b; Provyn et al., 2008; Scafoglieri et al., 2010c).

Accuracy and concordance of anthropometry for measuring regional fat distribution in adults aged 20–55 years

Objectives: This study aimed to assess the accuracy and concordance of anthropometrically derived prediction equations for the estimation of regional fat mass (FM) distribution.

Cross‐sectional content analysis of clinically applied circumferences

Eur J Clin Invest 2012; 42 (9): 961–966

Self-perceived fatigue in adolescents in relation to body composition and physical outcomes

BackgroundIncreased self-perceived fatigue (SpF) has already been identified in chronic conditions such as obesity, but it is also a growing problem in school-attending adolescents (±25%). This study tried to link body composition to SpF and physical activity/performance. Additionally, indicators for fatigue were determined.MethodsA total of 452 adolescents were recruited. Body composition was measured and physical activity, physical performance, and SpF were assessed. Based on the total SpF (Multidimensional Fatigue Inventory) outcomes, three groups were created: low fatigue (LF) medium fatigue (MF) and high fatigue (HF).ResultsFat was significantly lower in the LF group compared with MF (P<0,05) and HF (P<0.01). Grip endurance was increased in LF (P<0.05) and MF (P<0.01) compared with HF; similar results were found with the Cooper test. Sport Index was increased in LF compared with MF and HF (P<0.01). Fat and physical activity were related to fatigue (P<0.01). Decreased fatigue resistance, Sport Index and higher fat percentage increased the chance of being extremely fatigued.ConclusionThis study emphasizes the importance of using fat mass and fat percentage instead of body mass index when screening adolescents. To prevent increased SpF, it is necessary to stimulate youngsters to be physically active and to promote healthy behaviors.

Medical equipment (DXA) reliability and the management of its quality control by the clinical user

Dual energy X-ray absorptiometry (DXA) equipment is designed for human and animal research and clinical diagnoses. Controversial impression concerning its use is dictated by various critical appraisals and clinical reports. This study will cross-validate and compare DXA fan beam scannings with direct dissection and computed tomography (CT) scanning data. Twelve porcine carcasses, were measured with DXA and CT before dissection into its major components. Tissue samples were chemical and hydration analysed. The complete skeleton was ashed. This users-quality evaluation confirms that part of the existing problem results from erroneous terminology suggested by the manufacturer. The predictive values of DXA are good. The precision capacity of DXA variables resulted into significant differences indicating that clinical precision for the individual patient is at risk in particular for bone data.