Correlations between trabecular bone score, measured using anteroposterior dual-energy x-ray absorptiometry acquisition, and 3-dimensional parameters of bone microarchitecture: an experimental study on human cadaver vertebrae.

Developing a novel technique for the efficient, noninvasive clinical evaluation of bone microarchitecture remains both crucial and challenging. The trabecular bone score (TBS) is a new gray-level texture measurement that is applicable to dual-energy X-ray absorptiometry (DXA) images. Significant correlations between TBS and standard 3-dimensional (3D) parameters of bone microarchitecture have been obtained using a numerical simulation approach. The main objective of this study was to empirically evaluate such correlations in anteroposterior spine DXA images. Thirty dried human cadaver vertebrae were evaluated. Micro-computed tomography acquisitions of the bone pieces were obtained at an isotropic resolution of 93μm. Standard parameters of bone microarchitecture were evaluated in a defined region within the vertebral body, excluding cortical bone. The bone pieces were measured on a Prodigy DXA system (GE Medical-Lunar, Madison, WI), using a custom-made positioning device and experimental setup. Significant correlations were detected between TBS and 3D parameters of bone microarchitecture, mostly independent of any correlation between TBS and bone mineral density (BMD). The greatest correlation was between TBS and connectivity density, with TBS explaining roughly 67.2% of the variance. Based on multivariate linear regression modeling, we have established a model to allow for the interpretation of the relationship between TBS and 3D bone microarchitecture parameters. This model indicates that TBS adds greater value and power of differentiation between samples with similar BMDs but different bone microarchitectures. It has been shown that it is possible to estimate bone microarchitecture status derived from DXA imaging using TBS.

Management of fragility fractures in Switzerland: results of a nationwide survey.

A nationwide survey was conducted in Switzerland to assess the quality level of osteoporosis management in patients aged 50 years or older presenting with a fragility fracture to the emergency ward of the participating hospitals. Eight centres recruited 4966 consecutive patients who presented with one or more fractures between 2004 and 2006. Of these, 3667 (2797 women, 73.8 years old and 870 men, 73.0 years old in average) were considered as having a fragility fracture and included in the survey. Included patients presented with a fracture of the upper limbs (30.7%), lower limbs (26.4%), axial skeleton (19.5%) or another localisation, including malleolar fractures (23.4%). Thirty-two percent reported one or more previous fractures during adulthood. Of the 2941 (80.2%) hospitalised women and men, only half returned home after discharge. During diagnostic workup, dual x-ray absorptiometry (DXA) measurement was performed in 31.4% of the patients only. Of those 46.0% had a T-score < or =-2.5 SD and 81.1% < or =-1.0 SD. Osteoporosis treatment rate increased from 26.3% before fracture to 46.9% after fracture in women and from 13.0% to 30.3% in men. However, only 24.0% of the women and 13.8% of the men were finally adequately treated with a bone active substance, generally an oral bisphosphonate, with or without calcium / vitamin D supplements. A positive history of previous fracture vs none increased the likelihood of getting treatment with a bone active substance (36.6 vs 17.9%, ? 18.7%, 95% CI 15.1 to 22.3, and 22.6 vs 9.9%, ? 12.7%, CI 7.3 to 18.5, in women and men, respectively). In Switzerland, osteoporosis remains underdiagnosed and undertreated in patients aged 50 years and older presenting with a fragility fracture.

A gated single-photon avalanche diode array fabricated in a conventional CMOS process for triggered systems

A bidimensional array based on single-photon avalanche diodes for triggered imaging systems is presented. The diodes are operated in the gated mode of acquisition to reduce the probability to detect noise counts interfering with photon arrival events. In addition, low reverse bias overvoltages are used to lessen the dark count rate. Experimental results demonstrate that the prototype fabricated with a standard HV-CMOS process gets rid of afterpulses and offers a reduced dark count probability by applying the proposed modes of operation. The detector exhibits a dynamic range of 15 bits with short gated"on" periods of 10ns and a reverse bias overvoltage of 1.0V.

Gated Geiger mode avalanche photodiode pixels with integrated readout electronics for low noise photon detection

Avalanche photodiodes operated in the Geiger mode offer a high intrinsic gain as well as an excellent timing accuracy. These qualities make the sensor specially suitable for those applications where detectors with high sensitivity and low timing uncertainty are required. Moreover, they are compatible with standard CMOS technologies, allowing sensor and front-end electronics integration within the pixel cell. However, the sensor suffers from high levels of intrinsic noise, which may lead to erroneous results and limit the range of detectable signals. They also increase the amount of data that has to be stored. In this work, we present a pixel based on a Geiger-mode avalanche photodiode operated in the gated mode to reduce the probability to detect noise counts interfering with photon arrival events. The readout circuit is based on a two grounds scheme to enable low reverse bias overvoltages and consequently lessen the dark count rate. Experimental characterization of the fabricated pixel with the HV-AMS 0.35µm standard technology is also presented in this article.

MR-IMPACT II: Magnetic Resonance Imaging for Myocardial Perfusion Assessment in Coronary artery disease Trial: perfusion-cardiac magnetic resonance vs. single-photon emission computed tomography for the detection of coronary artery disease: a comparative multicentre, multivendor trial.

Aims Perfusion-cardiac magnetic resonance (CMR) has emerged as a potential alternative to single-photon emission computed tomography (SPECT) to assess myocardial ischaemia non-invasively. The goal was to compare the diagnostic performance of perfusion-CMR and SPECT for the detection of coronary artery disease (CAD) using conventional X-ray coronary angiography (CXA) as the reference standard. Methods and results In this multivendor trial, 533 patients, eligible for CXA or SPECT, were enrolled in 33 centres (USA and Europe) with 515 patients receiving MR contrast medium. Single-photon emission computed tomography and CXA were performed within 4 weeks before or after CMR in all patients. The prevalence of CAD in the sample was 49%. Drop-out rates for CMR and SPECT were 5.6 and 3.7%, respectively (P = 0.21). The primary endpoint was non-inferiority of CMR vs. SPECT for both sensitivity and specificity for the detection of CAD. Readers were blinded vs. clinical data, CXA, and imaging results. As a secondary endpoint, the safety profile of the CMR examination was evaluated. For CMR and SPECT, the sensitivity scores were 0.67 and 0.59, respectively, with the lower confidence level for the difference of +0.02, indicating superiority of CMR over SPECT. The specificity scores for CMR and SPECT were 0.61 and 0.72, respectively (lower confidence level for the difference: -0.17), indicating inferiority of CMR vs. SPECT. No severe adverse events occurred in the 515 patients. Conclusion In this large multicentre, multivendor study, the sensitivity of perfusion-CMR to detect CAD was superior to SPECT, while its specificity was inferior to SPECT. Cardiac magnetic resonance is a safe alternative to SPECT to detect perfusion deficits in CAD.

Two and three nucleon induced photon absorption

We have investigated the mechanisms leading to two and three body photon absorption in nuclei. At photon energies around the pion production threshold we obtain a fraction of three body absorption of less than 10% of the total, contradicting previous theoretical claims that it dominates the absorption process. The strength of the three body channel grows smoothly with the photon energy reaching a maximum of about 60% of the total direct absorption at energies of the photon around 400 MeV.

Effect of once-yearly zoledronic acid on the spine and hip as measured by quantitative computed tomography: results of the HORIZON Pivotal Fracture Trial.

Changes in bone mineral density and bone strength following treatment with zoledronic acid (ZOL) were measured by quantitative computed analysis (QCT) or dual-energy X-ray absorptiometry (DXA). ZOL treatment increased spine and hip BMD vs placebo, assessed by QCT and DXA. Changes in trabecular bone resulted in increased bone strength. INTRODUCTION: To investigate bone mineral density (BMD) changes in trabecular and cortical bone, estimated by quantitative computed analysis (QCT) or dual-energy X-ray absorptiometry (DXA), and whether zoledronic acid 5 mg (ZOL) affects bone strength. METHODS: In 233 women from a randomized, controlled trial of once-yearly ZOL, lumbar spine, total hip, femoral neck, and trochanter were assessed by DXA and QCT (baseline, Month 36). Mean percentage changes from baseline and between-treatment differences (ZOL vs placebo, t-test) were evaluated. RESULTS: Mean between-treatment differences for lumbar spine BMD were significant by DXA (7.0%, p < 0.01) and QCT (5.7%, p < 0.0001). Between-treatment differences were significant for trabecular spine (p = 0.0017) [non-parametric test], trabecular trochanter (10.7%, p < 0.0001), total hip (10.8%, p < 0.0001), and compressive strength indices at femoral neck (8.6%, p = 0.0001), and trochanter (14.1%, p < 0.0001). CONCLUSIONS: Once-yearly ZOL increased hip and spine BMD vs placebo, assessed by QCT vs DXA. Changes in trabecular bone resulted in increased indices of compressive strength.

Photon spectrum produced by the late decay of a cosmic neutrino background

We obtain the photon spectrum induced by a cosmic background of unstable neutrinos. We study the spectrum in a variety of cosmological scenarios and also we allow for the neutrinos having a momentum distribution (only a critical matter-dominated universe and neutrinos at rest have been considered until now). Our results can be helpful when extracting bounds on neutrino electric and magnetic moments from cosmic photon background observations.

Body composition using bio-impedance analysis in pediatric patients with inflammatory bowel disease. Corcordance with dual energy X-ray absorptiometry and comparison with healthy controls

Introduction: Growth is a central process in paediatrics. Weight and height evaluation are therefore routine exams for every child but in some situation, particularly inflammatory bowel disease (IBD), a wider evaluation of nutritional status needs to be performed. Objectives: To assess the accuracy of bio-impedance analysis (BIA) compared to the gold standard dual energy X-ray absorptiometry (DEXA) in estimating percentage body fat (fat mass; FM) and lean body mass (fat free mass; FFM) in children with inflammatory bowel disease (IBD). To compare FM and FFM levels between patients with IBD and healthy controls. Methods: Twenty-nine healthy controls (12 females; mean age: 12.7 ± 1.9 years) and 21 patients (11 females; 14.3 ± 1.3 years) were recruited from August 2011 to October 2012 at our institution. BIA was performed in all children and DEXA in patients only. Concordance between BIA and DEXA was assessed using Lin's concordance correlation and the Bland-Altman method. Between-group comparisons were made using analysis of variance adjusting for age. Results: BIA-derived FM% showed a good concordance with DEXA-derived values, while BIA-derived FFM% tended to be slightly higher than DEXA-derived values (table). No differences were found between patients and controls regarding body mass index (mean ± SD: 19.3 ± 3.3 vs. 20.1 ± 2.8 kg/m2, respectively; age-adjusted P = 0.08) and FM% (boys: 25.3 ± 10.2 vs. 22.6 ± 7.1%, for patients and controls, respectively; P = 0.20; girls: 28.2 ± 5.7 vs. 26.4 ± 7.7%; P = 0.91). Also, no differences were found regarding FFM% in boys (74.9 ± 10.2 vs. 77.4 ± 7.1%; P = 0.22) and girls (71.8 ± 5.6 vs. 73.5 ± 7.7%; P = 0.85). Conclusion: BIA adequately assesses body composition (FM%) in children with IBD and could advantageously replace DEXA, which is more expensive and less available. No differences in body composition were found between children with IBD and healthy controls.

Recommendations for raloxifene use in daily clinical practice in the Swiss setting.

BACKGROUND/AIM: Raloxifene is the first selective estrogen receptor modulator that has been approved for the treatment and prevention of osteoporosis in postmenopausal women in Europe and in the US. Although raloxifene reduces the risk of invasive breast cancer in postmenopausal women with osteoporosis and in postmenopausal women at high risk for invasive breast cancer, it is approved in that indication in the US but not in the EU. The aim was to characterize the clinical profiles of postmenopausal women expected to benefit most from therapy with raloxifene based on published scientific evidence to date. METHODS: Key individual patient characteristics relevant to the prescription of raloxifene in daily practice were defined by a board of Swiss experts in the fields of menopause and metabolic bone diseases and linked to published scientific evidence. Consensus was reached about translating these insights into daily practice. RESULTS: Through estrogen agonistic effects on bone, raloxifene reduces biochemical markers of bone turnover to premenopausal levels, increases bone mineral density (BMD) at the lumbar spine, proximal femur, and total body, and reduces vertebral fracture risk in women with osteopenia or osteoporosis with and without prevalent vertebral fracture. Through estrogen antagonistic effects on breast tissue, raloxifene reduces the risk of invasive estrogen-receptor positive breast cancer in postmenopausal women with osteoporosis and in postmenopausal women at high risk for invasive breast cancer. Finally, raloxifene increases the incidence of hot flushes, the risk of venous thromboembolic events, and the risk of fatal stroke in postmenopausal women at increased risk for coronary heart disease. Postmenopausal women in whom the use of raloxifene is considered can be categorized in a 2 × 2 matrix reflecting their bone status (osteopenic or osteoporotic based on their BMD T-score by dual energy X-ray absorptiometry) and their breast cancer risk (low or high based on the modified Gail model). Women at high risk of breast cancer should be considered for treatment with raloxifene. CONCLUSION: Postmenopausal women between 50 and 70 years of age without climacteric symptoms with either osteopenia or osteoporosis should be evaluated with regard to their breast cancer risk and considered for treatment with raloxifene within the framework of its contraindications and precautions.

Official Positions for FRAX® clinical regarding smoking from Joint Official Positions Development Conference of the International Society for Clinical Densitometry and International Osteoporosis Foundation on FRAX®.

The worldwide prevalence of smoking has been estimated at about 50% in men, and 10% in women, with larger variations among different populations studied. Smoking has been shown to affect many organ systems resulting in severe morbidity and increased mortality. In addition, smoking has been identified as a predictor of ten-year fracture risk in men and women, largely independent of an individual's bone mineral density. This finding has eventually lead to incorporation of this risk factor into FRAX®, an algorithm that has been developed to calculate an individual's ten-year fracture risk. However, only little, or conflicting data is available on a possible association between smoking dose, duration, length of time after cessation, type of tobacco and fracture risk, limiting this risk factor's applicability in the context of FRAX®.