Krouskop T A, Wheeler T M, Kallel F, Garra B S, Hall T
Department of Physical Medicine and Rehabilitation, Baylor College of Medicine, Houston, TX 77030, USA.
Ultrason Imaging. 1998 Oct;20(4):260-74. doi: 10.1177/016173469802000403.
To evaluate the dynamic range of tissue imaged by elastography, the mechanical behavior of breast and prostate tissue samples subject to compression loading has been investigated. A model for the loading was validated and used to guide the experimental design for data collection. The model allowed the use of small samples that could be considered homogeneous; this assumption was confirmed by histological analysis. The samples were tested at three strain rates to evaluate the viscoelastic nature of the material and determine the validity of modeling the tissue as an elastic material for the strain rates of interest. For loading frequencies above 1 Hz, the storage modulus accounted for over 93 percent of the complex modulus. The data show that breast fat tissue has a constant modulus over the strain range tested while the other tissues have a modulus that is dependent on the strain level. The fibrous tissue samples from the breast were found to be 1 to 2 orders of magnitude stiffer than fat tissue. Normal glandular breast tissue was found to have an elastic modulus similar to that of fat at low strain levels, but the modulus of the glandular tissue increased by an order of magnitude above fat at high strain levels. Carcinomas from the breast were stiffer than the other tissues at the higher strain level; intraductal in situ carcinomas were like fat at the low strain level and much stiffer than glandular tissue at the high strain level. Infiltrating ductal carcinomas were much stiffer than any of the other breast tissues. Normal prostate tissue has a modulus that is lower than the modulus of the prostate cancers tested. Tissue from prostate with benign prostatic hyperplasia (BPH) had modulus values significantly lower than normal tissue. There was a constant but not significant difference in the modulus of tissues taken from the anterior and posterior portions of the gland.
为评估弹性成像所成像组织的动态范围，已对乳腺和前列腺组织样本在压缩载荷下的力学行为进行了研究。对加载模型进行了验证，并用于指导数据收集的实验设计。该模型允许使用可视为均匀的小样本；组织学分析证实了这一假设。在三种应变速率下对样本进行测试，以评估材料的粘弹性，并确定将组织建模为感兴趣应变速率下的弹性材料的有效性。对于高于1Hz的加载频率，储能模量占复模量的93%以上。数据表明，在所测试的应变范围内，乳腺脂肪组织具有恒定的模量，而其他组织的模量取决于应变水平。发现来自乳腺的纤维组织样本比脂肪组织硬1至2个数量级。正常乳腺腺组织在低应变水平下的弹性模量与脂肪相似，但在高应变水平下，腺组织的模量比脂肪增加了一个数量级。乳腺肿瘤在较高应变水平下比其他组织更硬；导管原位癌在低应变水平下类似脂肪，在高应变水平下比腺组织硬得多。浸润性导管癌比任何其他乳腺组织都硬得多。正常前列腺组织的模量低于所测试的前列腺癌的模量。患有良性前列腺增生（BPH）的前列腺组织的模量值明显低于正常组织。从腺体前部和后部获取的组织的模量存在恒定但不显著的差异。
