RESUMO
The mechanical behavior of fetal dura mater was investigated by means of a biaxial tension test designed to simulate the constraints imposed on the membrane by the cranial bones. The experimental results are compared with the theoretical results obtained by using two published strain energy functions: one defined by Mooney and Rivlin (MR) and the other by Skalak, Tozeren, Zarda and Chien (STZC). The latter constitutive relations fit the experimental results consistently well. The STZC stiffness values from this series of tests are compared with those from membrane inflation tests performed previously and reported elsewhere by the authors.
Assuntos
Dano Encefálico Crônico/fisiopatologia , Dura-Máter/fisiopatologia , Complicações do Trabalho de Parto/fisiopatologia , Fenômenos Biomecânicos , Traumatismos do Nascimento/fisiopatologia , Lesões Encefálicas/fisiopatologia , Feminino , Idade Gestacional , Humanos , Recém-Nascido , Masculino , GravidezRESUMO
The authors present two methods of reducing refraction artifacts in ultrasonic computed tomography of the breast. Measuring the time of flight of sonic pulses by cross-correlation instead of leading-edge detection significantly reduces distortion and improves resolution in speed-of-sound images. Phase-insensitive reception of pulse energy across a large aperture array is shown to be superior to a conventional single-element transducer for attenuation imaging.
Assuntos
Doenças Mamárias/diagnóstico , Aumento da Imagem/métodos , Ultrassonografia , Feminino , Filtração/métodos , Humanos , Modelos EstruturaisRESUMO
The nonlinear mechanical behavior of fetal dura mater was tested experimentally and compared to two published nonlinear material strain energy functions, the Mooney-Rivlin and the Skalak, Tozeren, Zarda, and Chien (STZC). The STZC constitutive relations best fit the behavior of the dura mater and were used to describe quantitatively its stiffness. Runge-Kutta numerical procedures were used to fit the theoretical data to the experimental results. The material's stiffness was positively correlated with fetal weight (r = 0.67, p less than 0.05). These results are discussed and directions for future research indicated.
