Oelze Michael L, Zachary James F, O'Brien William D
Department of Electrical and Computer Engineering, University of Illinois, Urbana 61801, USA.
J Acoust Soc Am. 2002 Sep;112(3 Pt 1):1202-11. doi: 10.1121/1.1501278.
Characterization of tissue microstructure through ultrasonic backscatter is hypothesized to aid in detection and classification of diseased tissues. Radio frequency signals backscattered from tissues can be modeled according to the assumed shape, size, and distribution of scatterers in tissues. Power spectra of rf backscattered signals describe the frequency dependence of scatterers. Experimental measurements of ultrasonic backscatter from spontaneous mammary tumors in rats are obtained over the frequency range of 4 to 12 MHz. The power spectra measured from rat tumors are compared to theoretical power spectra derived from a 3D spatial autocorrelation function assuming a Gaussian distribution. Independent values of average scatterer diameter and acoustic concentration are obtained by approximating the measured power spectrum with a best-fit line. Enhanced B-mode images are made of the rat tumors and surrounding tissues with superimposed regions of interest quantified by estimated average scatterer sizes and acoustic concentrations. Scattering properties estimated inside the tumors and in surrounding tissues are shown to be distinct. Overall, estimates showed a 44.8% increase of average scatterer diameter inside the tumor as compared to tissues outside the tumor. With the exception of one rat, all estimates of the scatterers' average acoustic concentration inside the tumor were less than outside the tumors.
通过超声背向散射对组织微观结构进行表征，据推测有助于患病组织的检测和分类。从组织背向散射的射频信号可以根据组织中散射体的假定形状、大小和分布进行建模。射频背向散射信号的功率谱描述了散射体的频率依赖性。在4至12MHz的频率范围内获得了大鼠自发性乳腺肿瘤超声背向散射的实验测量结果。将从大鼠肿瘤测量得到的功率谱与从假设高斯分布的三维空间自相关函数导出的理论功率谱进行比较。通过用最佳拟合线逼近测量的功率谱，获得平均散射体直径和声浓度的独立值。用估计的平均散射体大小和声浓度对感兴趣区域进行量化，生成大鼠肿瘤和周围组织的增强型B模式图像。结果表明，肿瘤内部和周围组织的散射特性明显不同。总体而言，与肿瘤外组织相比，肿瘤内平均散射体直径估计增加了44.8%。除一只大鼠外，肿瘤内散射体平均声浓度的所有估计值均低于肿瘤外。
