Techavipoo Udomchai, Chen Quan, Varghese Tomy, Zagzebski James A, Madsen Ernest L
University of Wisconsin-Madison, Madison, WI 53706, USA.
IEEE Trans Ultrason Ferroelectr Freq Control. 2004 May;51(5):510-20.
Ultrasound elastography has developed into an imaging modality suitable for detection and diagnosis of cancers in the breast, prostate, and thyroid and for monitoring ablative therapies in the liver, kidneys, and other sites. In this article, a new approach is described that enables the reduction of noise artifacts in elastography without a significant reduction in either the contrast or spatial resolution. The technique uses angular-weighted compounding of local angular strains estimated from echo signals scanned at different insonification angles. Strain estimated along angular insonification directions can be separated into strain tensor components along the axial (direction of compression) and lateral directions. The mechanical stimulus is applied only along one direction. Angular-weighting factors are derived from the relationship between the axial and lateral strains under the assumption of tissue incompressibility. Experimental results using a uniformly elastic, tissue-mimicking phantom demonstrate the improvement in the signal-to-noise ratio obtained with angular-weighted compounding. Variation in the signal-to-noise ratio obtained using different angular increments also is investigated. Elastograms obtained from an inclusion phantom also demonstrate the improvement in contrast detail resolution obtained using spatial-angular compounding.
超声弹性成像已发展成为一种适用于检测和诊断乳腺、前列腺和甲状腺癌症以及监测肝脏、肾脏和其他部位消融治疗的成像方式。在本文中，描述了一种新方法，该方法能够减少弹性成像中的噪声伪像，而不会显著降低对比度或空间分辨率。该技术使用从不同声束入射角度扫描的回波信号估计的局部角应变的角度加权合成。沿角向声束入射方向估计的应变可分为沿轴向（压缩方向）和横向的应变张量分量。机械刺激仅沿一个方向施加。在组织不可压缩的假设下，根据轴向应变和横向应变之间的关系导出角度加权因子。使用均匀弹性的组织模拟体模进行的实验结果表明，角度加权合成可提高信噪比。还研究了使用不同角度增量获得的信噪比变化。从含杂质体模获得的弹性图也证明了使用空间角度合成可提高对比度细节分辨率。
