Federico Ponti

Accuracy, reproducibility and repeatability of ultrasonography in the assessment of abdominal adiposity.

RATIONALE AND OBJECTIVES Despite improvements in the methods used in body composition analysis, some goals remain far from clinical practice. Among them, the most important is the quantification of intra-abdominal adipose tissue. Fat distribution is a key point in the assessment of cardiovascular and metabolic risk status. The aim of this study was to define the accuracy, reproducibility, and repeatability of ultrasonography in the evaluation of abdominal adiposity. MATERIALS AND METHODS Twenty-six nonobese patients (group A) who underwent computed tomographic (CT) abdominal imaging and 29 obese patients (group B) were enrolled. Patients from both groups were independently evaluated using ultrasound by three radiologists; computed tomography-like conditions were reproduced, and six main parameters of subcutaneous and internal adiposity were measured (as well as three derived indexes) with both linear and convex probes. In group A, the same measurements were also obtained on CT images. Time spent for every ultrasound session was recorded. Results were analyzed using Lins concordance correlation (ρ), intraclass correlation, and linear regression analysis (and analysis of variance). RESULTS Three patients were excluded from group A after CT scans because of technical problems. Mesenteric fat thickness did not show significant correlations and reliability. Strong correlations between ultrasound and CT measurements were observed for all other visceral and subcutaneous parameters (ρ = 0.85-0.96). Intraobserver and interobserver agreement was excellent in both groups (repeatability: ρ = 0.83-0.99 for group A, ρ = 0.90-0.99 for group B; reproducibility: intraclass correlation coefficient = 0.90-0.99 for groups A and B). The mean time spent was 95 ± 21 seconds for group A (mean body mass index, 27.4 ± 2.4 kg/m(2)) and 129 ± 33 seconds for group B (mean body mass index, 37.3 ± 11.9 kg/m(2)). CONCLUSIONS Ultrasound is accurate, reproducible, and fast in the analysis of abdominal adiposity. It offers a regional, easy, and close-at-hand evaluation of subcutaneous and visceral fat compartments. This should be taken into consideration when clinical routine examinations are performed or to evaluate patients with specific metabolic diseases before and after treatment.

Effects of Three Different Testosterone Formulations in Female-to-Male Transsexual Persons

INTRODUCTION Gender dysphoria is characterized by a strong discomfort with the gender assigned at birth and the urge to live as a member of the opposite gender. The acquisition of phenotypic features of the desired gender requires the use of cross-sex hormones. Female-to-male (FtM) transsexual persons are treated with testosterone to induce virilization. AIM The aim of the study was to assess the effects of three different testosterone formulations on body weight and composition and metabolic and bone parameters. METHODS Forty-five FtM transsexuals were randomly assigned to receive testoviron depot (i.m.: 100 mg/10 days; n = 15), testosterone gel (50 mg/die; n = 15), and testosterone undecanoate (i.m.: 1,000 mg every 6 weeks for the first 6 weeks and then every 12 weeks, n = 15). FtM individuals were studied before, at week 30, and at week 54 of testosterone treatment. MAIN OUTCOME MEASURES Anthropometric, metabolic, bone, hematological, and biochemical parameters were evaluated at baseline and after 12 months of treatment. RESULTS Lean body mass significantly increased and fat mass decreased in all groups. No modifications were reported in fasting insulin and insulin sensitivity index. High-density plasma lipoprotein levels declined significantly and low-density lipoprotein concentrations increased significantly in the three groups. The activated partial thromboplastin time and factor I did not change while prothrombin time significantly increased in all groups. At week 54, all subjects were amenorrheic and time to amenorrhea did not differ between the three groups. Current general life satisfaction was increased in all subjects after 1 year of treatment. CONCLUSIONS One-year testosterone administration in FtM transsexuals appears to be very safe with no differences among the testosterone formulations used. Our study is preliminary, and the detection of subtle or long-term differences in the effects of the three formulations may require further larger and longer term studies in this and other populations.

Health and ageing: A cross-sectional study of body composition

BACKGROUND & AIMS The aim of this work was to provide a complete profile of body composition (BC) in healthy subjects and to investigate age and gender-related differences by dual-energy X-ray absorptiometry (DXA) and its latest developments. METHODS Italian volunteers among blood donors were enrolled in 5 different age bands (from 18 to 70 years old) to reach the threshold of 25 males and 25 females per single band (total: 250 subjects). All non-obese subjects who satisfied selective inclusion criteria were measured for weight and height and submitted to DXA, to determine fat mass (FM), non-bone lean mass (LM), bone mineral content and density, at regional and whole-body level. Moreover, the assessment of android visceral FM was performed by a new software. RESULTS A decrease in LM and increase in FM was observed with ageing, although the phenomenon was proved to be attenuated in women. The central and visceral redistribution of FM was also shown along lifetime, but women were not affected as men by this change. CONCLUSIONS This paper is a report on the status of healthy Italian subjects in their adulthood, to be used as a reference for future investigations on physiology, pathological human conditions, and differences between countries.

DXA: Technical aspects and application.

The key role of dual-energy X-ray absorptiometry (DXA) in the management of metabolic bone diseases is well known. The role of DXA in the study of body composition and in the clinical evaluation of disorders which directly or indirectly involve the whole metabolism as they may induce changes in body mass and fat percentage is less known or less understood. DXA has a range of clinical applications in this field, from assessing associations between adipose or lean mass and the risk of disease to understanding and measuring the effects of pathophysiological processes or therapeutic interventions, in both adult and paediatric human populations as well as in pre-clinical settings. DXA analyses body composition at the molecular level that is basically translated into a clinical model made up of fat mass, non-bone lean mass, and bone mineral content. DXA allows total and regional assessment of the three above-mentioned compartments, usually by a whole-body scan. Since body composition is a hot topic today, manufacturers have steered the development of DXA technology and methodology towards this. New DXA machines have been designed to accommodate heavier and larger patients and to scan wider areas. New strategies, such as half-body assessment, permit accurate body scan and analysis of individuals exceeding scan field limits. Although DXA is a projective imaging technique, new solutions have recently allowed the differential estimate of subcutaneous and intra-abdominal visceral fat. The transition to narrow fan-beam densitometers has led to faster scan times and better resolution; however, inter- or intra-device variation exists depending on several factors. The purposes of this review are: (1) to appreciate the role of DXA in the study of body composition; (2) to understand potential limitations and pitfalls of DXA in the analysis of body composition; (3) to learn about technical elements and methods, and to become familiar with biomarkers in DXA.

A 360-degree overview of body composition in healthy people: Relationships among anthropometry, ultrasonography, and dual-energy x-ray absorptiometry

OBJECTIVE The aim of this study was to test the relationship between anthropometry, ultrasonography, and dual-energy x-ray absorptiometry (DXA) for the assessment of body composition in clinical practice. METHODS The study was carried out in Italian blood donor volunteers belonging to five different age groups (18-70 y old; 25 men and 25 women per group; N = 250 participants; n = 125 men, n = 125 women). A complete history was collected and routine blood analyses were performed to confirm healthy status. All participants were submitted to whole-body DXA (tricompartmental analysis, regional, and total body), ultrasonography (abdominal adiposity evaluation), and anthropometric measurements. DXA was used as gold standard and its biomarkers were taken as reference for fat-lean mass balance, central-peripheral fat distribution, central or visceral fat, and subcutaneous fat. RESULTS Anthropometric and ultrasound parameters were closely associated with most of DXA parameters. Composite markers representative of central and abdominal visceral fat compartments were significantly correlated with waist circumference, waist-to-hip ratio, and intra-abdominal fat thickness by ultrasound, in both men and women (P < 0.025). As expected, subcutaneous depots were significantly correlated with maximum subcutaneous fat thickness measured by ultrasonography (P < 0.025). CONCLUSIONS Both anthropometry and ultrasonography provide a reliable estimate of visceral adipose tissue in a non-obese population compared with DXA, whereas anthropometry prediction of subcutaneous adiposity is weak. Physicians should be aware of the limits of these techniques for the assessment of body composition.

The role of DXA in sarcopenia

Abstract Sarcopenia is a condition characterized by progressive and generalized reduction in skeletal muscle mass and muscle strength, associated with an increased risk of adverse outcomes (disability, hospitalization, death). The growing attention in the last years, aiming to establish a consensus definition and treatment, reflects the interest of the scientific community toward this complex condition, which has many implications in clinical practice and public health. Dual-energy X-ray absorptiometry (DXA) is the gold-standard technique in the analysis of body composition at molecular level, providing assessment and quantification of fat mass, lean mass and bone mineral content, both in a single body region of interest and at whole-body level. In particular, through the assessment of non-bone lean mass parameters, such as appendicular lean mass adjusted for BMI or height (ALM/BMI and ALM/ht2, respectively), it is possible to discriminate subjects with “physiological” loss of muscle mass from those with “pathological” impoverishment of this compartment, referring to specific cutoff values validated in the literature, but keeping in mind the lack of standardization of DXA measures. In addition, it is useful in treatment planning, estimating resting energy expenditure, and in follow-up, because it allows quantifying with high reproducibility the modifications in BC, distinguishing when the change is biological (deterioration due to a progression of the disease or improvement due to treatment). Due to DXA favorability in terms of accuracy, simplicity, availability, low cost and low radiation exposure, its role in sarcopenia diagnosis is becoming increasingly important, emerging as reference assessment technique in muscle mass evaluation.

Abdominal adiposity by ultrasonography: A "pocket" database for reference standard in Italian people

AIMS To provide a reference standard database of ultrasonographic parameters of abdominal adiposity in healthy people. METHODS Italian non-obese volunteers among blood donors were enrolled in 5 age bands (from 18 to 70 year-old) to reach the threshold of 25 males and 25 females per single band (total: 250). All subjects were measured for weight, height and waist circumference and underwent ultrasonography (US) by an expert radiologist for the assessment of several abdominal fat thicknesses (minimum and maximum subcutaneous fat thickness, maximum preperitoneal fat thickness, intrabdominal fat thickness, aorto-mesenteric thickness, and mesenteric fat thickness). In addition, US data were normalized per waist circumference. RESULTS From 30s to 50s no statistically significant differences were achieved between males and females for the adiposity markers of visceral fat, while a relevant divergence was proved from 60s to 70s. During ageing a marked increase of the visceral fat compartment was observed in males, while only the preperitoneal circumference was significantly modified in females. CONCLUSIONS This paper reports on US parameters of abdominal adiposity of healthy Italian adults, to be used as a reference for daily clinical practice. Data could be also considered as control group for future investigations on physiology, pathological conditions, and differences between countries.

Imaging of diabetic bone

Diabetes is an important concern in terms of medical and socioeconomic costs; a high risk for low-trauma fractures has been reported in patients with both type 1 and type 2 diabetes. The mechanism involved in the increased fracture risk from diabetes is highly complex and still not entirely understood; obesity could play an important role: recent evidence suggests that the influence of fat on bone is mainly dependent on the pattern of regional fat deposition and that an increased amount of visceral adipose tissue negatively affects skeletal health.Correct and timely individuation of people with high fracture risk is critical for both prevention and treatment: Dual-energy X-ray Absorptiometry (currently the “gold standard” for diagnosis of osteoporosis) underestimates fracture risk in diabetic patients and therefore is not sufficient by itself to investigate bone status. This paper is focused on imaging, covering different modalities involved in the evaluation of skeletal deterioration in diabetes, discussing the limitations of conventional methods and exploring the potential of new tools and recent high-resolution techniques, with the intent to provide interesting insight into pathophysiology and fracture risk.

Correlation between DXA and laboratory parameters in normal weight, overweight and obese patients

OBJECTIVE The aim of this study was to review the existence and types of correlations between body composition densitometric parameters and laboratory values associated to cardiometabolic risk. METHODS We retrospectively analyzed data from 316 individuals in the weight range from normality to super-obesity, submitted to total body dual-energy x-ray absorptiometry (DXA) scans and routine biochemistry at S.Orsola-Malpighi Hospital from June 2010 to March 2014. The study included 182 women, 45.8 ± 13.4 y of age, with a body mass index (BMI) of 31.5 (± 11) kg/m2 (group F) and 134 men, 45.4 ± 13.6 y of age, with a BMI of 27.6 (± 7.8) kg/m2 (group M). All patients underwent whole-body scan (Lunar iDXA, GE Healthcare, Madison, WI, USA) and laboratory analysis (blood fasting glucose, total cholesterol, high-density lipoprotein cholesterol, tricylglycerides [TGs], aspartate aminotransferase, and alanine aminotransferase). Correlation between laboratory values and total body and regional fat mass (including visceral adipose tissue [VAT] and subcutaneous adipose tissue in the android region), and lean mass parameters were analyzed with linear and stepwise regressions analysis (significance limit, P < 0.05). Receiver operating characteristic curves were performed to assess the accuracy of the best-fit DXA parameter (VAT) to identify at least one laboratory risk factor. RESULTS In both groups, BMI and densitometric parameters showed a linear correlation with fasting blood glucose and TG levels and an inverse correlation with high-density lipoprotein cholesterol (P < 0.05), whereas no correlation was observed with total cholesterol levels. The only densitometric parameter retained in the final model of stepwise multiple regression was VAT for fasting blood glucose (group F: β = 0.4627, P < 0.0001; group M: β = 0.6221, P < 0.0001) and TG levels (group F: β = 0.4931, P < 0.0001; group M: β = 0.1990, P < 0.0261) independently of BMI. The optimal cutoff points of VAT to identify the presence of at least one laboratory risk factor were >1395 g and >1479 cm3 for men and >1281 g and >1357 cm3 for women. CONCLUSIONS DXA analysis of VAT is associated with selected laboratory parameters used for the evaluation of cardiometabolic risk and could be per se a helpful parameter in the assessment of clinical risk.

Bone mineral densitometry pitfalls

Osteoporosis is a widespread disease and represents a significant cause of morbidity and mortality in the elderly, especially in developed countries. The burden of osteoporosis is extremely high, both in terms of morbidity and in socioeconomic costs associated with the disease and its complications. Dual-energy X-ray absorptiometry (DXA) represents the gold standard for diagnosis and monitoring osteoporosis and low bone mass conditions. Over the past few years, there has been an impressive increase in the use of bone densitometry. The latest generation of scanners provides images of enhanced resolution with the important advantage of a very low radiation dose received by patients (approximately between 1 and 10 μSv). Despite all of this, DXA is often little understood among radiologists. To correctly perform and report a DXA examination, a deep knowledge of the appropriate clinical indications, scan acquisition modalities, images analysis, and potential pitfalls is required. Both the technologists who perform the test and the physicians who interpretate the results must have sufficient expertise in identifying common sources of mistakes (which can occur in every step of the examination, from patient preparation to data analysis) in order to avoid them.