Accuracy and the influence of marrow fat on quantitative CT and dual-energy X-ray absorptiometry measurements of the femoral neck in vitro

Abstract Bone mineral measurements with quantitative computed tomography (QCT) and dual-energy X-ray absorptiometry (DXA) were compared with chemical analysis (ChA) to determine (1) the accuracy and (2) the influence of bone marrow fat. Total bone mass of 19 human femoral necks in vitro was determined with QCT and DXA before and after defatting. ChA consisted of defatting and decalcification of the femoral neck samples for determination of bone mineral mass (BmM) and amount of fat. The mean BmM was 4.49 g. Mean fat percentage was 37.2% (23.3%–48.5%). QCT, DXA and ChA before and after defatting were all highly correlated (r>0.96,p<0.0001). Before defatting the QCT values were on average 0.35 g less than BmM and the DXA values were on average 0.65 g less than BmM. After defatting, all bone mass values increased; QCT values were on average 0.30 g more than BmM and DXA values were 0.29 g less than BmM. It is concluded that bone mineral measurements of the femoral neck with QCT and DXA are highly correlated with the chemically determined bone mineral mass and that both techniques are influenced by the femoral fat content

Vertebral deformities and functional impairment in men and women

Abstract The objective of this study was to assess the prevalence and health effects of vertebral deformities i

The pre-event stimulus ensemble: an analysis of the stimulus-response relation for complex stimuli applied to auditory neurons

Contains fulltext : mmubn000001_184714842.pdf (publisher's version ) (Open Access)Promotor : A. Vendrik162 p

Evaluation of postprocessing dual-energy methods in quantitative computed tomography. Part 2. Pracital aspects

Three facets of dual-energy quantitative computed tomography are studied: (1) the algorithm for postprocessing data (the methods of Cann, Laval-Jeantet et al, Goodsitt et al [two methods], and Nickoloff et al); (2) the influence of choice of tissue-equivalent materials for calibration; and (3) the difference between central and peripheral calibration. The different tissueequivalent materials include bone mineral-equivalent (K2HPO4 solutions and calcium hydroxyapatite), fat-equivalent (liquid paraffin, polyethylene, and 70% ethanol solution), and red marrow-equivalent (plastic). Deviation from the manufacturer's quoted content is least with central positioning of the calibration materials. The accuracy of estimates is best when the same tissueequivalent materials are used for calibration that are being measured. The deviations produced by the use of different tissueequivalent materials indicate the importance of using materials that mimic the components of bone most closely. The two methods of Goodsitt et al and the method of Nickoloff et al produced the best results

Determinação de zinco da sola do casco de bovinos leiteiros com ou sem lesões podais, suplementados ou não com levedura seca de cana-de-açúcar Evaluation of hoof sole zinc concentration of dairy cow with and without foot lesions, suplemented or not with drought yeast from sugarcane

Com o objetivo de estudar as concentrações de zinco da sola do casco de bovinos com e sem lesões podais, suplementados ou não com levedura seca, foram selecionadas e examinadas 60 vacas, escolhidas aleatoriamente, de um rebanho de 150 animais. Formaram-se quatro grupos de 15 animais, sendo o primeiro com animais com lesões podais e suplementados com levedura, o segundo com animais com lesões podais e sem suplementação de levedura, o terceiro com animais sem lesões podais e suplementados com levedura e o quarto com animais sem lesões podais e sem a suplementação de levedura. As concentrações de zinco da sola do casco foram determinadas por espectrometria de absorção atômica com chama (AAS). A comparação estatística das concentrações de zinco nas amostras foram submetidos à análise de variância, seguida pelo teste de Tukey, para comparação de médias. As médias das concentrações de zinco da sola do casco dos animais dos quatro grupos, quando comparadas estatisticamente, apresentaram diferença estatística significativa, somente nos animais com lesões podais e suplementados com levedura.<br>With the goal of studying the hoof sole zinc concentrations of cow with and without foot lesions, suplemented or not with dried yeast from sugarcane; 60 cows were chosen from milking of 150 animals. Four groups of 15 animals were formed being the first one of animals with foot lesions and with supplemental yeast, the second one of animals with lesions and without supplemental yeast, the third group of animals without foot lesions and with supplemental yeast and the fourth one of animals without foot lesions and without supplemental yeast. Hoof sole zinc was determined by the Atomic Absortion Spectrophotometry (AAS). The results were statistically evaluated by analysis of variable, followed by Tukey’s test to compare mean levels. The mean concentration of zinc in the hoof sole of the groups statistically, significant showed differences only in the animals with foot lesions and with yeast supplementation