Hip fractures in older adults have severe effects on patients’ morbidity as well as mortality, so it is crucial to avoid this injury through the early identification of patients at high risk. Currently, the diagnosis of osteoporosis and consequently hip fracture risk is done through the measurement of bone mineral density by a dual-energy X-ray absorptiometry (DXA) scan. However, studies show that this method is not accurate enough, and a high percentage of patients who sustain a hip fracture had non-osteoporotic DXA scans less than a year before the incidence. In this research, to enhance the hip fracture risk prediction, the effect of a femur’s geometry and bone mineral density distribution was considered in the hip fracture risk estimation. This was done through 2D and 3D statistical shape and appearance modeling of the proximal femur using standard clinical DXA scans. To assess the proposed techniques, destructive mechanical tests were performed on 16 isolated cadaveric femurs. Also, through collaboration with the Canadian Osteoporosis Study (CaMos), the proposed statistical techniques to predict the hip fracture risk were evaluated in a clinical population as well. The results of this study showed that new techniques can enhance hip fracture risk estimation; in the clinical study, 2D and 3D statistical modeling were able to improve identifying patients at high risk by 40% and 44% over the clinical standard method. Also, the percentage of correct predictions using 2D statistical models did not differ significantly from the 3D predictions. Therefore, by applying these techniques in clinical practice it could be possible to identify patients at high risk of sustaining a hip fracture more accurately and eventually reduce the incidence of hip fractures and the pain and social and economic burden that comes with it. / Thesis / Doctor of Philosophy (PhD) / Diagnosis of osteoporosis and consequently hip fracture risk is based on the measurement of bone mineral density in clinical imaging called DXA scanning. However, studies have shown that this method is not sufficient in identifying all patients at high risk of sustaining a hip fracture. The purpose of this work was to incorporate the geometry and bone mineral density distribution of the proximal femur in hip fracture risk prediction through image processing of DXA scans. Two algorithms of 2D and 3D statistical shape and appearance modeling were implemented and evaluated in a cadaveric study (comparing the predicted fracture load to measured ones) as well as a clinical study (comparing the fracture predictions to the fracture history of patients). The results indicated that new techniques can enhance hip fracture risk estimation compared to the clinical standard method, and hence the devastating injury can be prevented through applying protective measures.

Low energy availability (LEA) has been identified as the underlying etiology of the Female Athlete Triad and Relative Energy Deficiency in Sport (REDs) syndrome. The term energy availability (EA) describes the amount of dietary energy intake (EI) that is remaining to support physiological function after accounting for the energy cost of exercise. Exposure to LEA stimulates metabolic adaptations that may disrupt certain biological systems, such as endocrine function, and impair sports performance. Controlled laboratory research has shown suppression of bone formation biomarkers with accelerated rates of bone resorption after only three to five days of LEA in active females. Correcting LEA by increasing EI or decreasing exercise energy expenditure (EEE) may not be feasible for all athletes and additional approaches for protecting bone health during LEA require further investigation. Recent evidence suggests that brief bouts of high-impact exercise attenuate the increased rate of bone resorption in females with diet-induced LEA. However, it is unknown whether similar exercises have a protective effect on bone health when LEA is induced through a combination of dietary restriction and exercise. A gap also remains in the understanding of how EA fluctuates throughout the athletic season and what potential effect that has on body composition and performance outcomes. To address these gaps, we conducted two studies to investigate the interactions of EA, bone health, and body composition. The first investigation employed a randomized crossover design in which female runners underwent two, five-day experimental conditions of LEA consisting of dietary restriction and daily running (EA = 15 kcal·kg FFM-1·day-1). During one of the experimental conditions, participants also completed a bout of 50 jumping exercises daily. Serum markers of bone resorption (C-terminal cross-linking telopeptide of type 1 collagen [CTX-I]), bone formation (N-terminal propeptide of type 1 procollagen [PINP]), and hormonal profiles were compared between baseline and post-intervention using linear mixed effects modeling. We hypothesized that daily high-impact exercise would have a positive effect on bone by attenuating the rise in bone resorption. In contrast to our hypothesis, bone resorption marker CTX-I increased following both LEA conditions (+12%, P=0.004) with no difference in the response between the jumping and non-jumping conditions. Bone formation was not suppressed following either LEA condition. Concentrations of free triiodothyronine (T3), insulin-like growth factor-1, leptin, and insulin decreased in response to five days of LEA independent of condition (P<0.05); however, when taking into account condition, the decrease in free T3 was only statistically significant following the LEA condition without jumping (-27%, P=0.022, Cohen's d=0.87). Our findings suggest that high-impact jumping exercises are not an effective countermeasure to protect bone health during short-term LEA in female runners who continue to run routinely. In a second study, we conducted a longitudinal, observational study in collegiate male soccer players to investigate seasonal changes in EA and body composition. Measurements of EA, body composition, and sports performance were assessed at the start and end of the non-championship Spring athletic season. We hypothesized that EA would be positively associated with changes in body composition at the end of the three-month season. Despite most athletes reporting desires to gain total and/or lean body mass, no changes in EA or body composition were detected at the end of the season compared to the start. Furthermore, sports performance and bone density improved across the season regardless of individual changes in EA. These results indicate EA of collegiate male soccer players during the Spring season is sufficient to maintain current body composition and improve sports performance, but insufficient to support total and/or lean body mass gains. / Doctor of Philosophy / Adequate energy intake (EI) is essential for fueling athletic performance and supporting general health. Low energy availability (LEA) occurs when EI is insufficient to meet the energy demands of both exercise and basic health functions. Athletes with LEA may experience various repercussions such as suppressed metabolism, hormonal changes, and impaired bone health. Training adaptations may also be impaired by LEA, thereby affecting athletic performance. Daily high-impact jumping exercises have been shown to have a positive effect on bone health in women, even during periods of LEA caused by dietary restriction. However, this type of exercise intervention has not been tested in combination with other forms of daily exercise in women exposed to a controlled period of LEA. The purpose of these studies was to examine how exercise and EA affect bone health and body composition in recreational and competitive athletes. The first study investigated the effects of daily jumping exercises on markers of bone formation and breakdown during five days of LEA in female runners. The completion of 50 jumping exercises each day along with running on a treadmill was not shown to provide additional bone-protective benefits during LEA compared to running alone, as shown by similar rates of bone breakdown observed under both conditions. The second study investigated whether changes occur in EA or body composition in male collegiate soccer players over an athletic season. Despite most of the athletes reporting desires to gain weight or muscle during the season, there were no differences in body composition or EA at the end of the season compared to the start. However, there were significant improvements in aerobic fitness, relative strength, and bone density throughout the season.

The objectives of this research were to evaluate non-invasive measures of bone mineral content (BMC) and bone mineral density (BMD) as rapid, on-farm tools to assess phosphorus (P) status in dairy cows. In addition, the effects of parity and stage of lactation on measures of BMC of the fused 3rd and 4th metacarpal bone and of caudal vertebrae 14 and 15 were assessed. The caudal vertebrae and right front metacarpal (sample pairs) were excised from 107 Holstein cull cows following slaughter. Parity, age, and days in milk (DIM) of the donor animal were obtained for 43 pairs of samples. Samples were grouped by parity (1, 2, 3, and >4) and stage of lactation (Stage 1 = < 90 DIM, Stage 2 = > 90 and < 150 DIM, Stage 3 = >150 and < 250 DIM and Stage 4 = > 250 DIM). Samples were analyzed for BMC and BMD with dual energy X-ray absorptiometry (DXA), BMC with radiographic photometry (RP), breaking strength with mechanical methods, and mineral content with chemical procedures. Estimates of BMC obtained with RP and DXA were poorly related to chemical measures of actual BMC and to measures of breaking strength. In caudal vertebrae 14 and 15, increasing stage of lactation decreased energy to peak load with the lowest values observed in late lactation. Stage of lactation had no effect on BMC measured chemically in the caudal vertebrae or metacarpal. Parity did not affect breaking strength of the metacarpal or caudal vertebrae or total ash or P content of any bone. Results indicated that imaging techniques are not useful measures of BMC in mature dairy cattle. / Master of Science

Este estudo transversal teve por objetivo avaliar e relacionar entre si densidade mineral óssea (DMO), composição corporal e doença periodontal em 22 pacientes do gênero masculino, de 22 a 48 anos, portadores de obesidade, com IMC40kg/m2, candidatos à cirurgia bariátrica, atendidos no Hospital Amaral Carvalho (HAC) pelo Sistema Único de Saúde (SUS). Foram realizadas as avaliações antropométrica, do DXA e da condição periodontal. As variáveis qualitativas e quantitativas foram analisadas por meio da correlação linear pelo índice de correlação de Pearson, considerando o intervalo de confiança de 95% e nível de significância de 5% (p<0,05). O peso médio foi de 148kg (122-198); IMC médio de 48,8 (40,5-62,5); CMO, em média, de 3,31kg (2,7-4,1); DMO de corpo total média de 1,3 g/cm2 (1,1-1,5); e Z-score médio de 1,2 (0,0-2,9). A média de gordura corporal total foi de 43,3% (37,4-52,1), e a porcentagem de massa livre de gordura total foi de 56,6 (47,9-82,3). O IMG (Índice de massa gorda) médio foi de 20,6 (14,4-27,0), relação A/G de 1,2 (1.0-1,6) e o peso de tronco médio, 85,8kg (68,3-116,2). Dos pacientes, 29% apresentaram doença periodontal severa. Na casuística, ocorreu uma diferença a menor de 4,5kg (1,0 a 7,8) no peso de DXA comparado ao peso antropométrico, o que corresponde a uma diferença média de 3,06% (0,05-5,27). Na análise de correlação da avaliação odontológica vs resultado DXA, obteve-se apenas correlação significativa entre o índice de sangramento gengival e o IMG (p=0,031, R= -0,525). Pode-se concluir que o índice de massa corporal esteve inversamente relacionado ao sangramento gengival. Estudos futuros deverão ser conduzidos para esclarecer melhor estes achados. / The present cross-sectional study was aimed at evaluating and establishing the relation between bone mineral density (BMD), body composition and periodontal disease in 22 male patients, aged 22-48 years, with obesity (BMI of 40kg / m2), eligible for bariatric surgery, at Hospital Amaral Carvalho Hospital (HAC) by the Brazilian Unified Health System (SUS). Patients underwent anthropometric evaluations, whole-body DXA and periodontal assessment. Qualitative and quantitative variables were analyzed by means of linear correlation analyzes using the Pearsons correlation coefficient with 95% confidence interval and significance level of 5% (p <0.05). The data analyzes were performed with the aid of the SPSS v.22 program. Mean patients weight was 148kg (122-198); mean BMI, 48.8 (40.5-62.5); mean BMC, 3.31kg (2.7-4.1); mean whole-body BMD, 1.3 g / cm2 (1.1-1.5); and mean Z-score, 1.2 (0.0-2.9). Mean total body fat was 43.3% (37.4-52.1), and the percentage of total lean mass was 56.6 (47.9-82.3). Mean FMI (fat mass index) was 20.6 (14.4- 27.0); A/G ratio 1.2 (1.0-1.6) and mean trunk weight, 85.8 kg (68.3-116, 2). In the present study, 29% of the patients presented with severe periodontal disease. In the sample, there was a shortfall of 4.5 kg (1.0 to 7.8) in the DXA weight compared to anthropometric weight, which corresponds to an average difference of 3.06% (0.05- 5.27). In the correlation analysis between Dentistry assessment and DXA score, only a significant correlation was found between gingival bleeding index and FMI (p = 0.031, R = -0.525). It could be concluded that the body mass index was inversely related to de gingival bleeding. Future studies are needed to better clarify these findings.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A series of studies have been developed to evaluate and calibrate a bone densitometry device (Dual-energy X-ray Absorptiometry DXA) as an indirect method for body, carcass, and pork evaluation. Thus, the technology was tested for its precision in repeatability and reproducibility conditions. The effect of the sample edge, temperature, and thickness of the sample, and the effect of modifying the composition of the sample by the addition of tissue were also tested. In addition, software packages were evaluated. Finally, a protocol was developed to calibrate the method estimating the chemical composition of entire body and half carcass; and the dissected tissue composition of half carcass and primary cuts. The repeatability and reproducibility of the equipment were in general satisfactory; however, some regions of interest should be avoided, such as the trunk. The reduction of the edge perimeter did not change the results provided by the device. The temperature had a slight effect on the results; however, a wide variation in temperature is necessary to generate a small change in DXA results. The thickness variation of a sample with constant composition was one of the factors that most influenced the DXA measurements. For this reason, the techniques for standardization considering this factor are crucial to enable this device utilization. The evaluated software were Total body and Small Animal, each one with its three configurations totaling six studies. Both software could be used to estimate the composition of dissected tissues; however, the more extensive was the dissection the lower was the accuracy of the method. Thus, estimating an amount of a particular tissue in a half carcass was more accurate than estimating the same tissues in the primal cuts. The calibration procedure allowed obtaining translation models with good accuracy and precision to estimate the chemical composition and dissected tissues. In addition, measurements took in a condition could be used to estimate the composition in another one. However, when the measurement was more specific then greater was the precision of estimation. Accurate results were achieved after small methodological adjustments. This happened because the factors affecting DXA measurements were quantified and easily corrected with method standardization. The DXA is an important tool for animal evaluation. Thus, DXA should be considered in future studies. / Uma série de estudos foram desenvolvidos para avaliar e calibrar um equipamento de densitometria óssea (Dual-energy X-ray Absorptiomentry DXA) como método indireto para avaliação corporal, de carcaça e de cortes cárneos suínos. Assim, a tecnologia foi testada quanta à sua precisão em condições de repetibilidade e reprodutibilidade; além dos efeitos de borda da amostra, temperatura e espessura da amostra; e do efeito da modificação da composição da amostra pela adição de tecidos. Os pacotes de softwares também foram avaliados quanto às suas configurações. Por fim, um protocolo foi desenvolvido para calibrar o método para estimação da composição química corporal e de meia carcaça suína, além da composição de tecidos dissecados de meia carcaça e cortes primários. A repetibilidade e reprodutibilidade do equipamento foram em geral satisfatórias. Porém, algumas regiões de interesse devem ser evitadas, como a do tronco. A redução do perímetro da borda não modificou os resultados fornecidos pelo equipamento. A temperatura apresentou um leve efeito sobre os resultados, no entanto é necessária uma grande variação de temperatura para gerar uma pequena variação nos resultados DXA. A variação da espessura de uma amostra com composição constante foi um dos fatores que mais influenciaram as medidas tomadas com o equipamento. Visto isso, a padronização de técnicas considerando esse fator é fundamental para viabilizar a utilização desta tecnologia. Os softwares avaliados foram o Total body e Small animal cada um com suas três configurações totalizando seis estudos. Os dois softwares puderam ser empregados para estimação da composição de tecidos dissecados. No entanto, quanto mais extensiva foi a dissecção menor foi a precisão do método. Assim, a estimação da quantidade de um determinado tecido em uma meia carcaça foi mais precisa do que a estimação da composição de mesmo tecido nos cortes primários. Através da calibração do método, foi possível obter modelos de tradução com boa acurácia e precisão para estimar a composição química e de tecidos dissecados. Além disso, medidas tomadas em uma condição puderam ser utilizadas para estimar a composição em outra. Assim, a digitalização da meia carcaça pode ser utilizada para estimar a quantidade de músculo da paleta, por exemplo. No entanto, quanto mais específica foi a medida maior foi a precisão da estimativa. Resultados precisos foram alcançados depois de pequenos ajustes metodológicos, uma vez que, os fatores de influência sobre os resultados foram quantificados e eram de fácil correção através de padronização dos métodos. A ferramenta DXA mostrou-se um importante instrumento para avaliação animal. Portanto, a DXA deve ser considerada em futuras pesquisas.

Este estudo transversal teve por objetivo avaliar e relacionar entre si densidade mineral óssea (DMO), composição corporal e doença periodontal em 22 pacientes do gênero masculino, de 22 a 48 anos, portadores de obesidade, com IMC40kg/m2, candidatos à cirurgia bariátrica, atendidos no Hospital Amaral Carvalho (HAC) pelo Sistema Único de Saúde (SUS). Foram realizadas as avaliações antropométrica, do DXA e da condição periodontal. As variáveis qualitativas e quantitativas foram analisadas por meio da correlação linear pelo índice de correlação de Pearson, considerando o intervalo de confiança de 95% e nível de significância de 5% (p<0,05). O peso médio foi de 148kg (122-198); IMC médio de 48,8 (40,5-62,5); CMO, em média, de 3,31kg (2,7-4,1); DMO de corpo total média de 1,3 g/cm2 (1,1-1,5); e Z-score médio de 1,2 (0,0-2,9). A média de gordura corporal total foi de 43,3% (37,4-52,1), e a porcentagem de massa livre de gordura total foi de 56,6 (47,9-82,3). O IMG (Índice de massa gorda) médio foi de 20,6 (14,4-27,0), relação A/G de 1,2 (1.0-1,6) e o peso de tronco médio, 85,8kg (68,3-116,2). Dos pacientes, 29% apresentaram doença periodontal severa. Na casuística, ocorreu uma diferença a menor de 4,5kg (1,0 a 7,8) no peso de DXA comparado ao peso antropométrico, o que corresponde a uma diferença média de 3,06% (0,05-5,27). Na análise de correlação da avaliação odontológica vs resultado DXA, obteve-se apenas correlação significativa entre o índice de sangramento gengival e o IMG (p=0,031, R= -0,525). Pode-se concluir que o índice de massa corporal esteve inversamente relacionado ao sangramento gengival. Estudos futuros deverão ser conduzidos para esclarecer melhor estes achados. / The present cross-sectional study was aimed at evaluating and establishing the relation between bone mineral density (BMD), body composition and periodontal disease in 22 male patients, aged 22-48 years, with obesity (BMI of 40kg / m2), eligible for bariatric surgery, at Hospital Amaral Carvalho Hospital (HAC) by the Brazilian Unified Health System (SUS). Patients underwent anthropometric evaluations, whole-body DXA and periodontal assessment. Qualitative and quantitative variables were analyzed by means of linear correlation analyzes using the Pearsons correlation coefficient with 95% confidence interval and significance level of 5% (p <0.05). The data analyzes were performed with the aid of the SPSS v.22 program. Mean patients weight was 148kg (122-198); mean BMI, 48.8 (40.5-62.5); mean BMC, 3.31kg (2.7-4.1); mean whole-body BMD, 1.3 g / cm2 (1.1-1.5); and mean Z-score, 1.2 (0.0-2.9). Mean total body fat was 43.3% (37.4-52.1), and the percentage of total lean mass was 56.6 (47.9-82.3). Mean FMI (fat mass index) was 20.6 (14.4- 27.0); A/G ratio 1.2 (1.0-1.6) and mean trunk weight, 85.8 kg (68.3-116, 2). In the present study, 29% of the patients presented with severe periodontal disease. In the sample, there was a shortfall of 4.5 kg (1.0 to 7.8) in the DXA weight compared to anthropometric weight, which corresponds to an average difference of 3.06% (0.05- 5.27). In the correlation analysis between Dentistry assessment and DXA score, only a significant correlation was found between gingival bleeding index and FMI (p = 0.031, R = -0.525). It could be concluded that the body mass index was inversely related to de gingival bleeding. Future studies are needed to better clarify these findings.

Orientador: Guilherme de Paula Nogueira / Banca: Yuri Tani Utsunomiya / Banca: Marco Antonio Rodrigues Fernandes / Resumo: O objetivo desse estudo foi inferir a Densidade Mineral óssea (DMO) a partir da imagem radiográfica (Raios-X) usando como referência a DMO de uma escada de alumínio mensurada por Absorciometria por de Duas-Energias (DXA). Para isso foram utilizadas 30 amostras de tecido ósseo cortical e 30 amostras de tecido ósseo trabecular de osso bovino "in vitro". Foram mensurados neste estudo a Densidade Mineral Óssea (DMO), o Conteúdo Mineral Ósseo (CMO) ambos obtidos pelo densitômetro LUNAR®-DPX ALPHA; a Quantidade Mineral Óssea (QMO) massa das cinzas após a calcinação das amostras; a densidade real das amostras (dReal=massa/volume). Foram feitas 10 tomadas de RX com as 60 amostras, entremeadas pela escada de alumínio (referencial densitométrico). A correlação entre as técnicas (DR-tons de cinza e DXA g/cm2) gerou equações de regressão para cada uma das dez radiografias e permitiu inferir a densidade mineral óssea (DMODR), obtida através da conversão dos tons de cinza em densidade radiográfica pelo software ImageJ® para cada uma das 10 tomadas radiográficas; calculou-se então a média da densidade mineral óssea calculada pela densitometria radiográfica (XDMODR) de todas as dez radiografias. Foi observado que a média da densidade real das amostras foi de 2,2±0,23g/cm2 e 1,05±0,09g/cm2 enquanto que a média da densidade mensurada pelo DXA foi de 0,73±0,11g/cm2 e 0,22±0,11g/cm2, observou que a media da DMODR ficou em 0,93±0,11g/cm2 e 0,34±0,14 g/cm2 para o osso cortical e trabecular respect... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The aim of this study was to infer the bone mineral density (BMD) from the radiographic image (X-X) with reference to the BMD of an aluminum step wedge measured by absorptiometry Dual-energy (DXA). For this we used 30 samples of cortical bone 30 and cancellous bone tissue samples of bovine bone "in vitro". Were measured in this study Bone Mineral Density (BMD), bone mineral content (BMC) both obtained by densitometer LUNAR® DPX-ALPHA; Volume Bone Mineral (QMO) mass of ash after calcination of the samples; the real density of the samples (dReal = mass / volume). 10 taken RX were made with the samples 60, interspersed by aluminum step wedge (densitometric reference). The correlation between the techniques (gray DR-tones and DXA g / cm 2) generated regression equations for each of the ten X-rays and allowed to infer bone mineral density (DMODR) obtained by converting grayscale radiographic density by ImageJ® for each of the 10 radiographic taken. It was then calculated average bone mineral density calculated by X-ray densitometry (XDMODR) radiographs of all ten. Was observed that the average true density of the samples was 2.2±0.23g/cm2 and 1.05±0.09g/cm2 while the average density measured by DXA was 0.73±0.11g/cm2 and 0.22±0.11g/cm2 interesting that the average DMODR was 0.93±0.11g/cm2 and 0.34±0.14g/cm2 for cortical and cancellous bone respectively. The average of the BMC was 0.19±0.08g and 0.9±0.02g, and the average QMO 0.14±0.04g and 0.05±0 03g for cortical and cancellous bo... (Complete abstract click electronic access below) / Mestre

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No. of bitstreams: 1 fernandes_ra_me_araca_int.pdf: 2718642 bytes, checksum: 4dea3e0dc607519bbdbdb41a172e9277 (MD5) Previous issue date: 2019-01-18 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O objetivo desse estudo foi inferir a Densidade Mineral óssea (DMO) a partir da imagem radiográfica (Raios-X) usando como referência a DMO de uma escada de alumínio mensurada por Absorciometria por de Duas-Energias (DXA). Para isso foram utilizadas 30 amostras de tecido ósseo cortical e 30 amostras de tecido ósseo trabecular de osso bovino “in vitro”. Foram mensurados neste estudo a Densidade Mineral Óssea (DMO), o Conteúdo Mineral Ósseo (CMO) ambos obtidos pelo densitômetro LUNAR®–DPX ALPHA; a Quantidade Mineral Óssea (QMO) massa das cinzas após a calcinação das amostras; a densidade real das amostras (dReal=massa/volume). Foram feitas 10 tomadas de RX com as 60 amostras, entremeadas pela escada de alumínio (referencial densitométrico). A correlação entre as técnicas (DR-tons de cinza e DXA g/cm2) gerou equações de regressão para cada uma das dez radiografias e permitiu inferir a densidade mineral óssea (DMODR), obtida através da conversão dos tons de cinza em densidade radiográfica pelo software ImageJ® para cada uma das 10 tomadas radiográficas; calculou-se então a média da densidade mineral óssea calculada pela densitometria radiográfica (XDMODR) de todas as dez radiografias. Foi observado que a média da densidade real das amostras foi de 2,2±0,23g/cm2 e 1,05±0,09g/cm2 enquanto que a média da densidade mensurada pelo DXA foi de 0,73±0,11g/cm2 e 0,22±0,11g/cm2, observou que a media da DMODR ficou em 0,93±0,11g/cm2 e 0,34±0,14 g/cm2 para o osso cortical e trabecular respectivamente. A média da CMO foi de 0,19±0,9g e 0,08±0,02g e a media da QMO 0,14±0,04g e 0,05±0,03g para o osso cortical e trabecular respectivamente. Foi possível obter bons coeficientes de determinação entre todas as variáveis estudadas: CMO e QMO, R2 =0,747; DMO e dReal com R2 = 0,765; dReal e DMODR; DMO e XDMODR, respectivamente 0,764 e 0,856. Para as correlações foram usadas amostras de dois tecidos ósseos cortical e trabecular, o que sugere distinção entre as amostras com as metodologias utilizadas / The aim of this study was to infer the bone mineral density (BMD) from the radiographic image (X-X) with reference to the BMD of an aluminum step wedge measured by absorptiometry Dual-energy (DXA). For this we used 30 samples of cortical bone 30 and cancellous bone tissue samples of bovine bone "in vitro". Were measured in this study Bone Mineral Density (BMD), bone mineral content (BMC) both obtained by densitometer LUNAR® DPX-ALPHA; Volume Bone Mineral (QMO) mass of ash after calcination of the samples; the real density of the samples (dReal = mass / volume). 10 taken RX were made with the samples 60, interspersed by aluminum step wedge (densitometric reference). The correlation between the techniques (gray DR-tones and DXA g / cm 2) generated regression equations for each of the ten X-rays and allowed to infer bone mineral density (DMODR) obtained by converting grayscale radiographic density by ImageJ® for each of the 10 radiographic taken. It was then calculated average bone mineral density calculated by X-ray densitometry (XDMODR) radiographs of all ten. Was observed that the average true density of the samples was 2.2±0.23g/cm2 and 1.05±0.09g/cm2 while the average density measured by DXA was 0.73±0.11g/cm2 and 0.22±0.11g/cm2 interesting that the average DMODR was 0.93±0.11g/cm2 and 0.34±0.14g/cm2 for cortical and cancellous bone respectively. The average of the BMC was 0.19±0.08g and 0.9±0.02g, and the average QMO 0.14±0.04g and 0.05±0 03g for cortical and cancellous bone respectively. It was possible to obtain good determination coefficients between all variables: BMC and QMO, R2 = 0.747; BMD and dReal with R2 = 0.765; dReal and DMODR; BMD and XDMODR respectively 0.764 and 0.856. For correlations were used two samples of cortical and cancellous bone tissues, suggesting a difference between the samples with the methodologies used.

Notre objectif à court terme est d’établir des courbes de référence Française de la densité osseuse (DMO) et de la composition corporelle masculine une fois que nous aurons toutes les données issues de tous les centres. Nous avons donc réalisé deux études préliminaires dans le cadre de ce projet dont les objectifs sont les suivants :A) Etudier les déterminants de la DMO corps entier mais aussi spécifiques de site osseux en lien avec les mesures de composition corporelle, de force musculaire et de l’activité physique chez l’homme jeune B) Cross-calibration in vitro des paramètres de densité osseuse et de composition corporelle mesurés par l’absorptiométrie bi-photonique à rayons X (DXA) afin d’établir les facteurs correctifs à appliquer in vivo dans le cadre de notre projet de courbe de référence chez l’homme jeune.Grâce à la DXA, notre étude a confirmé que la masse maigre était le facteur le plus important associé aux paramètres de la DMO sur tous les sites osseux étudiés et que la masse grasse avait un impact négatif sur la DMO. Aucune association n'a été trouvée entre activité physique et DMO. La force de préhension était significativement mais modérément corrélée avec la DMO. Concernant la cross-calibration, les résultats ont montré que l’oscillation des résultats entre les différents DXA des centres est un sujet de préoccupation pour les études multicentriques et en particulier pour l’évaluation de la composition corporelle. La cross-calibration nous a permis de calculer les facteurs correctifs à appliquer sur les données issues des centres impliqués. Afin de limiter ces variations, il serait souhaitable de mettre au point un fantôme corps entier standard qui serait utilisé pour les études multicentriques. / Our short-term goal is to establish French reference curves of bone mineral density (BMD) and body composition once we have data from all centers. We have therefore carried out two preliminary studies for this project whose objectives are as follows: A) To study the determinants of whole body BMD but also bone site specific in relation to measurements of body composition, muscle strength and physical activity in young men B) Cross-calibration in vitro of bone mineral density and body composition parameters measured by dual energy X-ray absorptiometry (DXA) in order to establish in vivo the correction factors to be used in our baseline project in young men. Using DXA, our study confirmed that lean mass was the most important factor associated with BMD parameters at all bone sites and fat mass had a negative impact on BMD. Grip strength was significantly but moderately correlated with BMD at all sites. No association was found between physical activity and BMD. Regarding cross-calibration, the results showed that the oscillation of the results between the different DXA centers is a problem for multicenter studies and in particular for the evaluation of body composition. Cross-calibration allowed us to calculate the corrective factors to be applied to the data from the centers involved. In order to limit these variations, it would be desirable to develop a standard whole-body phantom that would be used for multicentre studies.

Ένα από τα βασικά χαρακτηριστικά της ομόζυγης β-θαλασσαιμίας είναι η οστεοπάθεια, η οποία αποτελεί μία πολυπαραγοντική διαταραχή, που δεν έχει πλήρως διευκρινισθεί. Μελετήσαμε τους οσφυϊκούς σπονδύλους 48 ασθενών με τις μεθόδους Dual-Energy X-ray Absorptiometry (DXA) και Quantitative Computed Tomography (QCT), και εστιάσαμε στις δομικές οστικές ιδιότητες, όπως προσδιορίζονται από την υψηλής ευκρίνειας Υπολογιστική τομογραφία (HRCT). Οι τιμές της οστικής πυκνότητας (BMD values) εκφράσθηκαν ως Z-scores και τα αποτελέσματα συσχετίσθηκαν. Εκτιμήθηκε η επίδραση της ηλικίας, του φύλου, του τύπου της θαλασσαιμίας και των ορμονικών παραγόντων στις τιμές ΒΜD. Αξιολογήσαμε, με βάση την HRCT, την ακεραιότητα του φλοιού και τον αριθμό και πάχος των δοκίδων της σπογγώδους ουσίας. Με βάση τον αριθμό των δοκίδων ταξινομήσαμε τους ασθενείς σε κλίμακα τριών βαθμίδων. Τα αποτελέσματά μας έδειξαν ότι ο συνολικός επιπολασμός της οστεοπόρωσης με την μέθοδο DXA ήταν 44 % και με την QCT 6 %. Και οι δύο μέθοδοι έδειξαν μία αρνητική συσχέτιση μεταξύ της ηλικίας και της BMD, ενώ οι ορμονικοί παράγοντες παρουσίασαν συσχετίσεις τόσο με τις μετρήσεις της QCT όσο και με τις αντίστοιχες της DXA. Ο συντελεστής συσχέτισης μεταξύ της BMD της DXA και της σπογγώδους BMD της QCT ήταν 0,545 (p<0,001) ενώ η αντίστοιχη τιμή για τα Ζ-scores ήταν 0,491 (p<0,001). Η ομαδοποίηση των ασθενών σε φυσιολογικούς, οστεοπενικούς και οστεοπορωτικούς, με βάση το Ζ της QCT, ήταν σε καλύτερη συμφωνία με την ταξινόμηση με βάση τον αριθμό των δοκίδων (K=0,209, p=0,053), σε σύγκριση με την ομαδοποίηση σύμφωνα με το Ζ της μεθόδου DXA (K=0,145, p=0,120). Η εκτίμηση του φλοιού με την HRCT έδειξε διακοπές στη συνέχειά του σε 15 ασθενείς. Και οι δύο μέθοδοι δείχνουν μία επιδείνωση της οστεοπόρωσης με την πρόοδο της ηλικίας. Η ανεπάρκεια των ορμονών συσχετίζεται με την θαλασσαιμική οστεοπόρωση, ενώ η οτπική εκτίμηση του φλοιώδους οστού δείχνει ότι οι ενδιάμεσου τύπου θαλασσαιμικοί πάσχουν σε μεγαλύτερο βαθμό από τους ασθενείς με μείζονα μορφή θαλασσαιμίας. Με τον αριθμό των δοκίδων ως δείκτη οστεοπόρωσης, φαίνεται ότι η QCT μπορεί να εκτιμήσει την οστεοπάθεια καλύτερα από την DXA. Δεδομένου ότι η QCT έχει την ικανότητα να μετρήσει την οστική πυκνότητα του σπογγώδους και φλοιώδους οστού, ξεχωριστά, μπορεί να παρέχει πρώιμη ένδειξη του ποιο από τα δύο μεταβάλλεται πιο γρήγορα και σε τι βαθμό. - / Osteopathy, as a major feature of homozygous beta-thalassaemia, is a multifactorial disorder, not fully understood. We studied the lumbar vertebrae of 48 patients using Dual-Energy X-ray Absorptiometry (DXA) and Quantitative Computed Tomography (QCT), and we focused on structural properties, assessed by High Resolution Computed Tomography (HRCT). Bone Mineral Density (BMD) values were expressed as Z scores and the results were correlated. The effect of age, sex, type of thalassaemia and hormonal factors on BMD was assessed. We estimated, with HRCT, the cortex integrity and the number and thickness of trabeculae; the latter were classified to a three-grade scale. Our results showed the overall prevalence of osteoporosis to be 44 % with DXA and 6 % with QCT. Both techniques revealed an inverse correlation between age and BMD, whereas hormonal factors demonstrated associations with QCT and DXA measurements. The correlation coefficient between DXA’s BMD and QCT’s trabecular BMD was 0.545 (p<0.001) whereas the corresponding value for Z scores was r=0.491 (p<0.001). The classification of the patients into normal, osteopenic and osteoporotic categories, using QCT’s Z, was in better agreement with the assignment based on trabecular number (K=0.209, p=0.053) than the classification using DXA’s Z (K=0.145, p=0.120). Cortex evaluation by HRCT showed discontinuity in 15 patients. Both methods indicate a progression of osteoporosis with age. Hormonal deficiency is associated with thalassaemic osteoporosis whereas the visual estimation of cortex indicate that TI could be more affected than TM. Using the trabecular number as an indicator of osteoporosis, it seems that QCT may evaluate osteopathy better than DXA. Since the former has the ability to measure trabecular and cortical BMD separately, it could give early indication of which changes more rapidly and to what degree.