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<p> An accurate estimation of Body Segment Parameters (BSPs) is needed to understand human movement. These include segment mass, centre of mass, and moment of inertia about the centre of mass. Bone density scanners, such as DPX, can measure BSPs, but are limited to only two dimensions. MRI produces images in three dimensions, but cannot directly measure mass. For this study, MRI was used in conjunction with a DPX scan of the human body. The result was the development of a method to estimate mass, and subsequently, centre of mass, and moment of inertia from MRI images. Next, ellipses were created from the dimensions of transverse plane slices (produced from MRI). Three different density profiles were applied to the ellipses, and mass, centre of mass and moment of inertia about the centre of mass of each slice was calculated. It was found that constant density transverse plane ellipses could be used to estimate BSPs for most regions of the body. Photogrammetry can also be used to generate the dimensions of ellipses that represent transverse plane slices. Therefore, the suitability of photogrammetry to estimate slice BSPs was tested. It was found that depending on the density profile used, photogrammetry is an effective method for estimating BSPs. An exception to this estimation was in the chest, where ellipses may not be representative of the body. </p> / Thesis / Master of Science (MSc)

<p>Uvod: Osteoporoza je sistemsko oboljenje skeleta koje se karakteri&scaron;e smanjenjem mase kosti i promenama u ko&scaron;tanoj strukturi, &scaron;to sve ima za posledicu povećanu sklonost ko&scaron;tanog tkiva ka prelomima. Prema preporuci Svetske zdravstvene organizacije, dijagnoza osteoporoze postavlja se ukoliko je T-score -2,5 SD i ispod te vrednosti, a normalan nalaz ako je vrednost T-score -1,0 SD i iznad te vrednosti. Danas se smatra da je zlatni standard u dijagnostici osteoporoze primena dvostruke X apsorpcione denzitometrije lumbalne kičme i kuka putem koje se dobiju vrednosti ko&scaron;tane mase Bone mineral density i T-score. Međutim, poznato je da postoje faktori rizika koji utiču na redukciju mase kosti na taj način &scaron;to smanjuju maksimum mase kosti koji se stiče do 35. godine života i / ili ubrzavaju inače normalan proces postepenog i blagog smanjenja mase kosti koji počinje posle 35. godine života i na taj način povećavaju rizik za frakture. Takođe, poznato je da neki od faktora rizika i njihova udruženost može dovesti do povećanog rizika za frakture i nezavisno od ko&scaron;tane mase i T-score. Ciljevi istraživanja : 1. Utvrditi ko&scaron;tanu masu u postmenopauznih žena primenom dvostruke X apsorpcione denzitometrije. 2. Analizirati distribuciju faktora rizika u pacijentkinja sa T-score ispod -2.5 SD u poređenju sa pacijentkinjama sa T-score iznad -1.0 SD. 3. Utvrditi odnos između statističkog prostora koji čine pojedinačni i udruženi faktori rizika (sa karakteristikama svakih od njih) i mase kosti određene denzitometrijski. Materijal i metode rada: Istraživanje je koncipirano delom kao prospektivna, a delom kao retrospektivna studija koja je sprovedena kod pacijentkinja u postmenopauznom periodu života, životne dobi od 50 do 80 godina. Nakon urađene dvostruke X apsorpcione denzitometrije lumbalne kičme i kuka ispitivane pacijentkinje su same popunjavale upitnik uz pomoć medicinske sestre ili lekara. Nakon dobijenih podataka pacijentkinje su podeljene u dve grupe: sa osteoporozom i bez osteoporoze. U grupi sa osteoporozom je bilo 270 pacijentkinja, a u grupi bez osteoporoze 250 pacijentkinja. Potom je sprovedena statistička obrada podataka. Nakon sveobuhvatne analize dobijenih rezultata istraživanja izvedeni su sledeći zaključci: 1.Ustanovljeno je da 60% postmenopauznih žena prosečne životne dobi od 67.0 &plusmn; 7.0 godina ima osteoporozu odnosno vrednost T-score &le; -2.5 SD. 2. Postoji statistička značajna povezanost između ko&scaron;tane mase i sledećih faktora rizika: pozitivna porodična anamneza na osteoporozu i frakture, telesna težina, telesna visina, ranije frakture, česti padovi i smanjenje u visini vi&scaron;e od 3 cm. 3. Analizom faktora rizika se dobijaju karakteristike osoba sa osteoporozom: pozitivna porodična anamneza na osteoporozu i frakture, manja telesna težina i telesna visina, smanjenje u visini vi&scaron;e od 3 cm, česti padovi i ranije frakture. 4. Hipertireoidizam i hiperparatireoidizam, reumatoidni artritis, primena kortikosteroidne terapije su faktori rizika koji su vi&scaron;e zastupljeni kod ispitivanih pacijentkinja sa osteoporozom. 5. Pu&scaron;enje, rana menopauza, alergija na mleko bez adekvatne supstitucije sa kalcijumom i nedovoljan boravak na suncu bez adekvatne supstitucije sa vitaminom D su faktori rizika koji su vi&scaron;e zastupljeni kod ispitivanih pacijentkinja sa osteoporozom. 6. Najveći doprinos celini daje pozitivna porodična anamneza na osteoporozu i frakture (20.99%), zatim slede telesna težina, telesna visina, Index telesne mase (19.03%), ranije frakture, česti padovi, smanjenje u visini vi&scaron;e od 3 cm (18.41%), pu&scaron;enje i nedovoljna fizička aktivnost (12.75%), alergija na mleko i nedovoljan boravak na suncu (12.14%), rana menopauza (8.72%), hipertireoidizam, hiperparatireoidizam, reumatoidni artritis (7.93%). 7. Analizom tri grupe obeležja koja daju najveći doprinos celini ustanovljeno je da pozitivna porodična anamneza na frakture (37.7%) i telesna težina (31.3%) predstavljaju major faktore rizika za osteoporozu. 8. Matematičkom obradom dolazi se do formule pomoću koje bi sa verovatnoćom od 64.0 % mogla predvideti osteoporoza, a sa verovatnoćom 73.2 % odsustvo osteoporoze, čime se između ostalog u na&scaron;em istraživanju donekle relativizuje neophodnost određivanja ko&scaron;tane mase u proceni rizika za prelome i u proceni potrebe za uvođenje antiosteoporotične terapije. Formula je +.214 O +.562 F +.202 R +.223 P +.335 S +.493 T +.057 V +.020 9. Potrebno je testirati dobijenu formulu na ispitivanim pacijentkinjama i nastaviti istraživanje na većem uzorku na faktore rizika koji nisu pokazali statističku značajnost.</p> / <p>Introduction: Osteoporosis is a systematic disease of skeleton characterized by the reduction of bone mass and changes in bone structure which result in the increased aptitude of bone tissue to fractures. According to the suggestion of the World Health Organization, the diagnosis for osteoporosis is set if the T-score is -2.5 SD and below it and the normal report if the value of T-score is -1.0 SD and above it. Nowadays, it is considered that the golden standard in osteoporosis diagnostic is the use of double X absorption densitometry of lumbal spine and hipe which provides the values of bone mass Bone mineral density as well as T-score. However, it has been known that there are risk factors whish influence the reduction of bone mass by reducing maximum bone mass gained by the age of 35 and/or by quckening, the normal process of gradual and mild reduction of bone mass starting after 35 and in that way increase the risk toward fractures. It mas also been known that some of the risk factors and their correlation may cause the increasement of the risk factor toward fractures not having the connection with the bone mass and T-score. Researchment aims: 1. Determine bone mass in postmenopausal women using double X absorption densitometry. 2. Analyse distribution of risk factors in patients whith the T-score below -2.5 SD comparing to the patients with T-score above -1.0SD. 3. Determine the relation between statistical space made by individual and associated risk factors (with the characteristics of each of them) and the bone mass specified by densitometry. Material and methods of working: Researchment is outlined partly as prospective and partly as retrospective study which was carried out in patients in postmenopausal life period, aged 50-80. After applying double X absorption densitometry of lumbal spine and hip the examined patients did the questionnaire by themselves whith the help of nurses and doctors. After obtaining the data, patients were divided into two groups: with and without osteoporosis. There were 270 patients in the group with osteoporosis and 250 of them without it. Thereafter, the statistic data processing was carried out. After the overall analysis of obtained results of researchment, following conclusions were conducted: 1. It has been determined that 60 % of postmenopausal women of average age 67.0&plusmn;7.0 have osteoporosis, in other words, their T-score is &le; -2.5 SD. 2. There is statistically important relationship between the bone mass and following risk factors: positive family anamnesis to osteoporosis and fractures, body weight, height, previos fractures, frequent falls and reduction of height for more than 3 cm. 3. Analysing the risk factors, characteristics of persons with osteoporosis have been obtained: positive family anamnesis to osteoporosis and fractures, smaller body weight and height, the reduction in height for more than 3 cm, frequent falls and previous fractures. 4. Hyperthyroidism and hyperparathyroidism, rheumatoid arthritis and the usage of corticosteroid therapy are the risk factors more incident in the examined patients with osteoporosis. 5. Smoking, early menopause, allergy to milk with no adequate substitution of calcium and insufficient exposition to sun rays with no adequate substitution of vitamine D are the risk factors more incident in patients with osteoporosis. 6. The largest contribution to the total makes positive family anamnesis to osteoporosis and fractures (20.99%), followed by body weight, height, Body mass index (19.03%), previos fractures, frequent falls and reduction in height for more than 3 cm (18.41%), smoking and insufficient physical activity (12.75%), allergy to milk and insufficient exposition to the sun (12.14%), early menopause (8.72%), hyperthyroidism and hyperparathyroidism, rheumatoid arthritis (7.93%). 7. By the analysis of all three goups of features giving the largest cintribution to the total, it has been determined that positive family anamnesis to fractures (37.7%), and body weight (31.3%), present the major risk factors for osteoporosis. 8. By mathematical processing we obtain the formula which can with the probability of 64.0% predict osteoporosis, and with the probability of 73.2% the absence of osteoporosis, which can, among other things in our research to some extent, require relative necessity for introduction of antiosteoporotic therapy. The formula is +.214 O +.562 F +.202 R +.223 P +.335 S +.493 T +.057 V +.020. 9. It is necessary to test the formula obtained in examined patients and continue the reseachment, on larger sample, of risk factors which have not shown statistic importance.</p>

Over the past 30 years, obesity has been primarily identified by the body mass index (BMI). Due to its ease of calculation, the BMI has become the most widely used diagnostic tool to identify weight problems. This study examined the association between hypertension and BMI in White, Black, and Hispanics in the United States. The study’s hypothesis was that this relationship was weaker in Blacks than in the other groups. Data for the study came from the 2007-2008 and 2009-2010 National Health and Nutrition Examination Surveys. The association was weaker in Black men than in Whites or Hispanics on a univariate basis, and at most BMI levels on a multivariate basis. For females, it was also weaker in Blacks at most BMI levels on a univariate basis. However, multivariate logistic regression analysis did not indicate that the hypothesis held for Black women when adding covariates to the models.

The purpose of this thesis project was to determine the precision error of dual-energy x-ray absorptiometry (DXA) derived bone mineral density (BMD) at regions of interest (ROI) that are clinically relevant to persons with spinal cord injury (SCI), and secondarily to compare the precision error between a group of persons who are able-bodied and a group of persons with chronic SCI. Over 2 visits, four DXA scans at sites of the distal femur, proximal tibia, and calcaneus were completed in 10 persons who are able-bodied and 10 persons with chronic SCI. Using forearm sub region analysis, we measured the BMD and calculated the precision error for a total of 7 ROI at these sites. Despite a lower BMD at every ROI in the group of persons with chronic SCI compared to the group of persons who are able-bodied (range, 33 – 56%), the relative precision error was similar between groups. However, there was a trend for greater precision error in persons with SCI at a whole bone ROI of the distal femur (RMS-CV of 8.40% vs. 5.63%) and a ROI of the posterior calcaneus body (RMS-CV of 3.52% vs. 1.78%) when compared to persons who are able-bodied. Further, the ROI of the posterior calcaneus body appeared to have a lower precision error in persons who are able-bodied (RMS-CV, 1.78%) than the distal femur and proximal tibia (RMS-CV range 3.26 – 5.63%). The results from this study suggest that the precision error of DXA derived BMD is similar between persons with SCI and persons who are able-bodied, and that the posterior calcaneus body may be a more precise site than the distal femur and proximal tibia.

Dual energy x-ray absorptiometry (DXA) provides accurate measurements of percent body fat (%BF) and lean body mass (LBM), however no reference standards currently exist using DXA-derived data. This study’s purpose was to develop reference data sets for DXA-derived %BF and LBM, and to characterize the agreement of obesity classifications between BMI (≥30 kg/m2) and %BF (≥25% for men and ≥30% for women). 2,761 subjects were scanned from 2003-2013 using either the GE Medical Systems Lunar Prodigy or Lunar iDXA. Normative reference tables displaying mean values and select percentiles were created for %BF and LBM across defined age groups for both genders. Mean %BF and LBM closely reflected data from the National Health and Nutrition Examination Survey across age groups in both genders. Agreements between BMI and %BF were 97% when identified as obese and 33% when identified as non-obese. Future research should consider creating a national registry for DXA-derived measurements. / School of Physical Education, Sport, and Exercise Science

Orientador: Gil Guerra Júnior / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-19T19:08:43Z (GMT). No. of bitstreams: 1 Goncalves_EzequielMoreira_D.pdf: 5365817 bytes, checksum: 7f7c98bf013498181e9a1d0f32614cfc (MD5) Previous issue date: 2012 / Resumo: Objetivos: a) Validar equações com base nas espessuras de dobras cutâneas (EDC) para estimar o percentual de massa gorda (%MG) e na impedância bioelétrica (BIA) para a massa isenta de gordura (MIG) em pacientes com hiperplasia adrenal congênita por deficiência da enzima 21-hidroxilase (HAC-D21OH); b) desenvolver equações específicas para estes pacientes para estimar o %MG e MIG, utilizando os valores determinados pela absorciometria por dupla emissão de raio X (DXA) como referência; e c) avaliar a relação entre os parâmetros da massa óssea (MO) determinados pela ultrassonometria quantitativa (QUS) das falanges proximais e sua capacidade de diagnosticar a baixa MO para a idade cronológica em comparação ao DXA em pacientes com HAC-D21OH. Casuística: Foram avaliados 71 pacientes de ambos os sexos, com idades entre seis e 27 anos. Métodos: Foram realizadas medidas antropométricas, de BIA, de DXA e de QUS em um mesmo dia. Foram testadas quatro equações (Eq. 1, 2, 3 e 4), previamente publicadas para a estimativa do %MG e quatro equações (Eq. 5, 6, 7, e 8) para a estimativa da MIG em kg, todas específicas para o sexo e faixa etária. Foram utilizados o teste t de Student, os parâmetros da regressão linear simples e a concordância entre os métodos para testar a validade das equações, regressão linear múltipla para desenvolver os novos modelos e a análise dos parâmetros da curva ROC para avaliar a capacidade diagnóstica do QUS. Resultados: Eq. 1, 2, 3, e 4, apresentaram alta correlação (R>0,80), porém subestimaram significativamente (p<0,01) os valores de %MG em comparação ao DXA. Com relação à MIG, apesar de todas as equações apresentarem R> 0,95, no geral apenas uma apresentou validade considerada aceitável (Eq. 6, grupo masculino). Foram desenvolvidas e validadas quatro equações propostas no presente estudo específicas para a estimativa do %MG e uma para a estimativa da MIG em pacientes HAC-D21OH. Os parâmetros do QUS apresentaram valores variando entre: 0,57-0,74 (R), 62,5-100% (sensibilidade) e 21-64,4% (especificidade) em relação ao DXA. Conclusão: As equações específicas para indivíduos com HAC-D21OH demonstraram maior validade para estimar a MIG e principalmente o %MG, comparadas as equações previamente publicadas e desenvolvidas a partir de amostras com pessoas saudáveis. O QUS apresentou relação significativa, porém moderada e baixa capacidade de diagnosticar a baixa MO para a idade cronológica quando comparado ao DXA nestes pacientes / Abstract: Objectives: a) To evaluate the accuracy of skinfold-based models, to estimate the percentage of fat mass (%FM) and the bioelectrical impedance analysis (BIA) to estimate fat-free mass (FFM) in patients with congenital adrenal hyperplasia due to 21-hydroxylase deficiency (CAH-21OHD); b) to develop specific equations for these patients to estimate the % MG and MIG using dual-energy X-ray absorptiometry (DXA) as the reference method; and c) to evaluate the relationship between the parameters of bone mass (BM) determined by quantitative ultrasound of proximal phalanges (QUS) and the ability to diagnose low bone mass for chronological age in comparison to DXA in patients with CAH-21OHD. Patients: Seventy one patients of both genders, with age ranged from six and 27 years were inclued. Methods: Anthropometric measurements, BIA, DXA and to QUS were evaluated in the same day. Four equations (Eq. 1, 2, 3 and 4) previously published to estimate the %FM, and four equations (Eq. 5, 6, 7, and 8) to estimated the FFM, all specific for sex and age, the Student t test, the parameters of simple linear regression and the agreement between methods were used to test the validity of the equations, multiple linear regression to develop the new model and the parameters of the ROC curve to evaluate the diagnostic ability of QUS. Results: The four equations (Eq. 1, 2, 3, and 4) were highly correlated (R>0.80), but the %FM values were significantly underestimated (p<0.01) when compared to DXA. With respect to MIG, despite all the equations presented R>0.95, only one had acceptable validity (Eq. 6 for males). Four new specific equations to estimated %FM and one FFM were developed and validate in patients with CAH-21OHD. QUS parameters showed values ranging from 0.57 to 0.74 (R), 62.5 to 100% (sensitivity) and 21 to 64.4% (specificity) compared to DXA. Conclusion: The new specific equations for patients with CAH-21OHD showed greater validity to estimate FFM and mainly the %FM compared to previously equations published and developed with samples from healthy pearsons. The QUS showed a significant relationship, but moderate and low ability to diagnose low bone mass for chronological age when compared to DXA in these patients / Doutorado / Saude da Criança e do Adolescente / Doutor em Saude da Criança e do Adolescente

Made available in DSpace on 2014-06-12T23:02:48Z (GMT). No. of bitstreams: 2 arquivo8577_1.pdf: 1277931 bytes, checksum: 3fa83084d4bb4f85991aa2e7f000febd (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2006 / A obesidade é uma excessiva acumulação de energia sob a forma de gordura corporal com prejuízos à saúde. O aumento da prevalência de obesidade em diferentes populações leva a acreditar que esta condição clínica caminha para ser a mais importante causa de doença crônica no mundo. O objetivo deste trabalho foi o de avaliar a importância da obesidade em especial a central e seus fatores de risco à saúde em homens adultos jovens por meio de revisão da literatura, bem como, realizar um estudo comparativo entre duas técnicas de avalição da composição corporal: a Antropometria e o Dual Energy X-ray absorptiometry (DXA). O delineamento do estudo foi do tipo transversal com seleção aleatória. Participaram 45 indivíduos com idades entre 20 e 30 anos, distribuídos em três grupos segundo o Índice de Massa Corporal (IMC), nas categorias peso normal, pré-obeso e obeso I. O referido estudo originou uma nova equação de predição para a gordura centralizada utilizando o perímetro abdominal (Pab) e a gordura do tronco medida pelo DXA em homens adultos jovens, permitindo ainda classificar os referidos indivíduos em risco à saúde de acordo com o Z-score usando a quantidade de gordura estimada pela referida equação

We quantified confidence intervals (CIs) for T-scores for the lumbar spine and hip and determined the practical effect (impact on diagnosis) of variability around the T-score cutpoint of -2.5. Using precision data from the literature for GE Lunar Prodigy dual-energy X-ray absorptiometry (DXA) systems, the 95% CI for the T-score was ±0.23 at the lumbar spine (L1-L4), ± 0.20 at the total hip, and ±0.41 at the femoral neck. Thus, T-score variations of ±0.23 or less at the spine, ±0.20 at the total hip, and ±0.41 at the femoral neck are not statistically significant. When diagnosing osteoporosis, T-scores in the interval -2.3 to -2.7 for spine or total hip (after rounding to conform to guidelines from the International Society for Clinical Densitometry) and -2.1 to -2.9 for femoral neck are not statistically different from -2.5. Better precision values resulted in smaller 95% CIs. This concept was applied to actual clinical data using Hologic DXA systems. The study cohort comprised 2388 white women with either normal or osteopenic spines in whom the densitometric diagnosis of osteoporosis would be determined by hip T-scores. When evaluating actual patient T-scores in the range -2.5 ± 95% CI, we found that the diagnosis was indeterminate in approximately 12% of women when T-scores for femoral neck were used and in 4% of women when T-scores for total hip were used, with uncertainty as to whether the classification was osteopenia or osteoporosis. We conclude that precision influences the variability around T-scores and that this variability affects the reliability of diagnostic classification.

Introduction: We determined the prevalence of left-right differences in hip bone mineral density (BMD) by dual-energy x-ray absorptiometry (DXA) and the resultant consequence, namely: the frequency at which patients would be classified differently if lumbar spine and only one hip (rather than both hips) were measured. Methods: This was a retrospective DXA scan reanalysis of 3012 white women ≥50 yrs who had scans of both hips using Hologic DXA systems. The difference between left and right hips was considered significant if it exceeded the least significant change (LSC) for any of three hip subregions (total hip, femoral neck, trochanter). The number of women with osteoporosis in both hips, the left hip only, or the right hip only was determined by lowest T-score from total hip, femoral neck, or trochanter. Results: Despite high left-right correlations of subregion BMD, significant left-right differences in BMD were common: the difference exceeded the LSC for 47% of women at total hip, 31% at femoral neck, and 56% at trochanter. Left-right differences in BMD that exceeded the LSC affected the percent agreement of left-right hip classification: for all women irrespective of spine status, there was 77% classification (diagnostic) agreement in hip pairs in which the left-right hip BMD difference exceeded the LSC versus 87% agreement in which LSC was not exceeded (significant difference in proportions, P<0.0001). The greatest risk of different classification would occur in women with normal spines as the diagnosis might be determined by hip T-scores. Using L1-4 lumbar spine T-scores, 1229 women were normal at the spine. Twenty-four (2%) were osteoporotic at both hips. However, 12 women (1%) were osteoporotic only in the left hip (significantly different from zero, P<0.001) and 11 (1%) only in the right hip (P<0.001); of these 23 women, the difference in BMD between the osteoporotic hip and the contralateral hip exceeded the LSC in 16 (70% of those with osteoporosis in only one hip). Using L1-4 lumbar spine T-scores, 1159 women were osteopenic at the spine. Of these, 126 (11%) were osteoporotic at both hips, 54 (5%) only in the left hip (P<0.001), and 42 (4%) only in the right hip (P<0.001); of these 96 women, the difference in BMD between the osteoporotic hip and the contralateral hip exceeded the LSC in 56 (58% of those with osteoporosis in only one hip). Conclusions: A statistically significant number of women with osteoporosis are potentially classified differently when scanning only one hip as a result of the high prevalence of left-right differences in BMD. Although the percentages are low, the total number of women affected may be large. From a public health perspective, the practice of scanning both hips could potentially identify more women with osteoporosis and may help prevent future hip fractures. © 2006 International Osteoporosis Foundation and National Osteoporosis Foundation.