Trabecular bone score in healthy ageing

OBJECTIVE

The main aim of this work was to report on trabecular bone score (TBS) by dual-energy X-ray absorptiometry (DXA) of healthy Italian subjects to be used as a reference standard for future study in clinical and research settings. The secondary aim was to investigate the link between TBS and conventional parameters of bone and body composition by DXA.

METHODS

250 individuals of 5 age bands (spanning from 18 to 70 years of age, equally distributed for both age and sex) were prospectively recruited. A lumbar spine (LS) DXA scan (Lunar iDXA™; GE Healthcare, Madison, WI) was acquired for each subject and then analysed with the latest version of TBS iNsight v. 2.1 (Med-Imaps, Pessac, France) software. LS bone mineral density (LS BMD), Z-score, T-score and TBS values were collected. Pearson's test was used to investigate the correlations between TBS and LS BMD and the influence of age, body mass index (BMI) and body composition on these parameters.

RESULTS

A significant decrease of TBS and LS BMD was observed with ageing in both males (TBS mean values from 1.486 to 1.374; LS BMD mean values from 1.219 to 1.187) and females (TBS mean values from 1.464 to 1.306; LS BMD mean values from 1.154 to 1.116). No statistically significant difference was achieved among males and females of the same age group for both TBS and LS BMD, with the exception of the fifth age group. A significant correlation was found between LS BMD and TBS values in both sexes (r  = 0.555-0.655, p < 0.0001). BMI influenced LS BMD but not TBS. TBS values were inversely correlated with some fat mass parameters, in particular with visceral adipose tissue (in males: r = -0.332, p < 0.001; in females: r = -0.348, p < 0.0001). No significant correlation was found between TBS and total lean mass, opposite to LS BMD (in males: r = 0.418; p < 0.0001; in females: r = -0.235; p < 0.001).

CONCLUSION

This report is an attempt to start building a database for healthy Italian people providing age- and sex-specific reference curves for TBS. This could help clinicians to improve patient management in the detection of impaired bone mineral status and to monitor bone changes.

ADVANCES IN KNOWLEDGE

The study reports TBS values of a selectively enrolled Italian healthy population, ranging from younger to older ages and including males as a reference standard. Moreover, links between body composition and TBS are explored.

Liver in the analysis of body composition by dual-energy X-ray absorptiometry

OBJECTIVE

To investigate the predictive value for hepatic steatosis of a new software for the quantification of visceral fat by dual-energy X-ray absorptiometry (DXA) and to design new regions of interest (ROIs).

METHODS

Adult volunteers were prospectively screened for hepatic steatosis by ultrasonography to obtain a well-balanced population according to the presence/absence of the disease. 90 adult patients without steatosis and 90 with steatosis (mild, 53.3%; moderate, 37.7%; and severe, 10.0%) were recruited. On the same day, all subjects were submitted to blood testing and to anthropometric and whole-body DXA for body composition evaluation. A new software for android visceral fat assessment was employed, and six new "liver-suited" ROIs as well as two modified android ROIs were designed. Their association with steatosis grade was tested by correlation analysis.

RESULTS

Fat mass (FM) of the new ROIs showed the highest correlation coefficients with steatosis grade (ρ = 0.610-0.619; p < 0.001), which was also confirmed by multivariate analysis. On the whole population, the new ROIs maintained the highest predictive role for liver steatosis, with areas under the receiver operating characteristic curve up to 0.820 ± 0.032. Inter- and intra-operator agreement for the new ROIs was excellent (k = 0.915-1.000 and k = 0.927-1.000).

CONCLUSION

New ROIs could be designed, standardized and implemented in DXA whole-body scan to provide more specific and predictive values of hepatic lipid content.

ADVANCES IN KNOWLEDGE

This is the first study to investigate the predictive value for hepatic steatosis of visceral and regional FM assessed on the hepatic site by DXA in comparison with ultrasonography, anthropometry and surrogate markers derived by previously validated algorithms (fatty liver index).

Localizer sequences of magnetic resonance imaging accurately identify osteoporotic vertebral fractures

The aim of the present study was to evaluate the performance of sagittal MR localizer (MR-loc), in terms of diagnostic accuracy and intra- and inter-observer agreement in the detection of vertebral fractures (VFs). Three-hundred MR examinations of the thoracic and/or lumbar spine were randomly collected. A semi-quantitative approach was used and morphometric analysis was performed when a VF was suspected. MR-loc images were evaluated blindly by three radiologists in two different sessions. A full diagnostic sagittal T1-weighted fast spin echo MR sequence was used as standard of reference (RS). Degenerative arthritis was also scored on RS. Only vertebral bodies which were assessable by both MR-loc and RS were considered for the analysis. Area under the receiver operating characteristic curve (AUROC), Cohen kappa statistic, and linear-by-linear association were used for statistical analysis. Kappa values were compared by means of the z distribution. A total of 2186 vertebrae were analysed in 300 MRI exams (147 males, 153 females, 59.4±16.4y.o.). Sixty-seven out of 2136 (3.1%) VFs were identified in 23/300 (7.7%) patients submitted to MRI. In the detection of VFs, sensitivity and specificity of MR-loc were both 100% (accuracy AUROC=1.000). Inter-observer agreement was excellent (k=0.938±0.013), while intra-observer agreement was perfect (k=1.000). The diagnostic performance was independent from degenerative arthritis, vertebral level, type and grade of VFs. MR-loc is a simple but accurate tool in the detection of VFs. It should be introduced for systematic evaluation in the detection of VFs in MR examinations performed in daily clinical practice.

Reliability and accuracy of scout CT in the detection of vertebral fractures

OBJECTIVE

The aim of the present study was to evaluate the reliability of scout CT (sCT) lateral radiograph, in terms of diagnostic accuracy and intra- and interobserver agreement in the detection of vertebral fractures (VFs).

METHODS

300 CT examinations of the thoracic and/or lumbar spine were collected and independently analysed by 3 musculoskeletal radiologists in 2 different sessions. A semi-quantitative approach was used for VF assessment on sCT, and morphometric analysis was performed when a VF was suspected. Results of multiplanar sagittal CT reconstructions interpreted by the most expert radiologist were considered as gold standard. Arthrosis was also scored. Only vertebral bodies assessable by both sCT and gold standard were considered for the analysis. Area under the receiver operating characteristic curve (AUROC), Cohen's kappa statistic and linear-by-linear association were used for statistical analysis.

RESULTS

1522 vertebrae were considered (130 males and 170 females; ages, 73.0±2.8 years). 73 of 1522 (4.8%) VFs were identified in 34/300 patients (11.3%). In the detection of VFs, the sensitivity and specificity of sCT were 98.7% and 99.7%, respectively. Accuracy (AUROC=0.992±0.008), as well as interobserver agreement (k=0.968±0.008), was excellent. Intra-observer agreement was perfect (k=1.000). Performance of this method was independent of arthrosis, vertebral level and type and grade of VFs.

CONCLUSION

sCT is a simple but very accurate method for the detection of VFs. It should be introduced as a spine evaluation tool for the detection of VFs in examinations that are performed for other diagnostic purposes.

ADVANCES IN KNOWLEDGE

sCT lateral radiograph is an accurate tool for the detection of VFs. This technique may be used with several advantages in clinical practice.

Relationships between total and regional adiposity and epicardial fat in obese women: how can dual-energy X-ray absorptiometry be associated with echocardiographic epicardial fat measurements?

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

Obesity is an increasingly prevalent metabolic disorder and it is associated with a large number of comorbidities, including cardiovascular diseases. Adipose tissue is an active endocrine organ and its ectopic depots and distribution have different metabolic meanings on risks for health; as a matter of fact, epicardial fat seems to play a specific role in cardiovascular diseases. The use of dual-energy X-ray absorptiometry (DXA) to evaluate and follow-up patients affected by obesity is becoming a very important point in the management of the disease.

WHAT THIS STUDY ADDS

An investigation of the association between epicardial fat and regional adiposity by DXA in female obese patients. The total amount of central (trunk) fat mass is more strongly correlated than android visceral fat mass to epicardial thickness in obese women. In the interpretation of whole-body DXA data, physician should consider trunk fat mass for good and independent predictivity on epicardial fat depots. Our aim was to analyse in a population of obese women the relationship between the amount of epicardial fat as measured by transthoracic echocardiography (US) and the parameters of regional adiposity by dual-energy X-ray absorptiometry (DXA), with particular reference to a new software for visceral fat assessment and to a new 'heart-suited' regions of interests (ROIs). Sixty patients who satisfied technical inclusion criteria underwent whole-body DXA scan and US on the same day. Total and android fat mass (FM) and FM percentage (FM%) were considered as well as visceral fat (VAT) subcompartment in the android region; moreover, six new ROIs were designed on whole-body DXA images for the investigation of adiposity parameters at heart level. US provided epicardial fat thickness (EPI-thickness) and area (EPI-area), as measured following previously validated methods. Body mass index (BMI), gynoid and lower limbs (FM and FM%) were found not statistically correlated with EPI-thickness. The highest correlation was achieved by trunk FM (and FM%, with r = 0.544 and 0.480 respectively, P < 0.001), followed by ROI-1 FM (ROI-1 was drawn following thoroughly the cardiac profile), and android FM. Multivariate analysis including age, weight, BMI, trunk FM and the new ROIs (added one by one), retained in the final model trunk FM. Correlations of DXA with EPI-area were superimposable. In obese women, VAT or other new-designed ROIs are not better correlated than traditional ROIs (i.e. trunk) with epicardial fat amount.