Seven breast cancer specimens were examined with diffraction-enhanced imaging at 18 keV with a silicon crystal with use of the silicon 333 reflection in Bragg mode. Images were compared with digital radiographs of the specimen, and regions of increased detail were identified. Six of the seven cases (86%) showed enhanced visibility of surface spiculation that correlated with histopathologic information, including extension of tumor into surrounding tissue.

Samples of in-vitro canine liver tissue have been subjected to mechanical testing in order to determine their viscoelastic properties, namely, the frequency-dependent complex modulus. Samples include normal tissue, as well as thermal lesions prepared by radio frequency ablation at various temperatures and cook times. Results are fit according to the Kelvin-Voigt and Kelvin-Voigt Fractional Derivative models. The data agrees much better with the Kelvin-Voigt Fractional Derivative model, suggesting that this model may better represent the viscoelastic properties of some soft tissues. Results are then used in introducing the concept of the complex modulus contrast, whose applications to elastography are discussed.

Mechanical properties of biological tissues are of interest for assessing the performance of elastographic methods that evaluate the stiffness characteristics of tissue. The mechanical properties of interest include the frequency-dependent complex moduli, storage and loss moduli of tissues. Determination of the mechanical properties of biological tissues is often limited by proper geometry of the sample, as well as homogeneity of the stress-strain relationship. Measurements were performed on in vitro canine liver tissue specimens, over a frequency range from 0.1 to 400 Hz. Tests were conducted using an EnduraTEC ELF 3200, a dynamic testing system for determining the mechanical properties of materials. Both normal tissues and thermal lesions prepared by radio frequency ablation were tested. Experiments were conducted by uniaxially compressing tissue samples using Plexiglas platens larger than the specimens and measuring the load response. The resulting moduli spectra were then fit to a modified Kelvin-Voigt model, called the Kelvin-Voigt fractional derivative model. The data agree well with the model and in comparing the results from the normal tissue with that of the thermal lesions, the concept of a complex modulus contrast is introduced and its applications to elastography are discussed.

No abstract

No abstract