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1.
Radiology ; 267(3): 830-6, 2013 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-23440323

RESUMO

PURPOSE: To determine the accuracy and precision of thoracic phantomless bone mineral density (BMD) measurements obtained on coronary artery calcium (CAC) computed tomography (CT) scans by using a variety of commercially available CT scanners. MATERIALS AND METHODS: The institutional review board approved this Health Insurance Portability and Accountability Act-compliant study. A total of 4126 asymptomatic subjects (2022 [49%] men, 2104 [51%] women; mean age, 63.7 years ± 11.8 [standard deviation]) underwent CAC CT with the use of a quantitative CT calibration phantom for evaluation of subclinical atherosclerosis. Two hundred eighty subjects also underwent CT of the chest, abdomen, and pelvis (C7 through L5). Mean BMD of three consecutive thoracic vertebrae (in the T7-T10 range) was measured in all 4126 subjects. Individual calibration factors for each phantom insert and a general calibration factor for the spine were determined for each CT scanner model. The study population was then divided into three subgroups: All calibration factors were generated from group 1 (n = 1536) and were applied and tested in group 2 (n = 1587), and effects of various image acquisition parameters were assessed in group 3 (n = 1003). Accuracy (bias) and precision of thoracic phantomless BMD measurements across 14 CT scanner models from five manufacturers were determined. RESULTS: Phantomless BMD values correlated highly with standard phantom-based quantitative CT BMD values (r = 0.987, P < .001). Bias was 3.9% ± 1.4 for phantomless BMD measurements, and the mean coefficient of variation for the general calibration factor was 4.9% ± 2.4. CONCLUSION: Phantomless BMD can be measured accurately on CAC CT scans acquired with a variety of CT scanners without additional radiation exposure.


Assuntos
Densidade Óssea , Angiografia Coronária/métodos , Vértebras Torácicas/diagnóstico por imagem , Tomografia Computadorizada por Raios X/métodos , Idoso , Análise de Variância , Calibragem , Angiografia Coronária/instrumentação , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Imagens de Fantasmas , Doses de Radiação , Interpretação de Imagem Radiográfica Assistida por Computador , Tomografia Computadorizada por Raios X/instrumentação
2.
Radiology ; 257(2): 434-40, 2010 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-20807844

RESUMO

PURPOSE: To create standard thoracic bone mineral density (BMD) values for patients undergoing cardiac computed tomography (CT) by using thoracic quantitative CT and to compare these BMDs (in a subpopulation) with those obtained by using lumbar spine quantitative CT. MATERIALS AND METHODS: The institutional review board approved this HIPAA-compliant study. A total of 9585 asymptomatic subjects (mean age, 56 years; age range, 30-90 years) who underwent coronary artery calcium scanning, including 4131 women, were examined. Patients with vertebral deformities or fractures were excluded. Six hundred forty-four subjects (322 of whom were female) also underwent lumbar quantitative CT. The mean thoracic vertebral BMDs for both sexes were reported separately in a subgroup of subjects aged 30 years and in 29 age-based subgroups in 2-year intervals from ages 30 to 90 years. The formulas used to calculate the female T score (T(f)) and the male T score (T(m)) on the basis of thoracic quantitative CT measurements were as follows: T(f) = (BMD(im) - 222)/36, and T(m) = (BMD(im) - 215)/33, where BMD(im) is the individual mean BMD. Comparisons between thoracic quantitative CT and lumbar quantitative CT measurements, as well as analyses of intraobserver, interobserver, and interscan variability, were performed. RESULTS: The young-subgroup mean BMD was 221.9 mg/mL ± 36.2 (standard deviation) for the female subjects and 215.2 mg/mL ± 33.2 for the male subjects. The mean thoracic BMDs for the female and male subjects were found to be 20.7% higher and 17.0% higher, respectively, than the values measured with lumbar quantitative CT (P < .001 for both comparisons). A significant positive association between the thoracic and lumbar quantitative CT measurements (r > 0.85, P < .001) was found. Intraobserver, interobserver, and interscan variabilities in thoracic quantitative CT measurements were 2.5%, 2.6%, and 2.8%, respectively. CONCLUSION: There was a significant association between the mean thoracic and lumbar BMDs. Therefore, standard derived measurements (young-subgroup BMD ± standard deviation) based on these data can be used with thoracic CT images to estimate the bone mineral status.


Assuntos
Densidade Óssea , Osteoporose/diagnóstico por imagem , Vértebras Torácicas/diagnóstico por imagem , Tomografia Computadorizada por Raios X/métodos , Adulto , Idoso , Idoso de 80 Anos ou mais , Eletrocardiografia , Feminino , Humanos , Vértebras Lombares/diagnóstico por imagem , Masculino , Pessoa de Meia-Idade , Imagens de Fantasmas , Reprodutibilidade dos Testes
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