Anisotropy of the apparent frequency dependence of backscatter in formalin fixed human myocardium
Anisotropy of the apparent frequency dependence of backscatter in formalin fixed human myocardium
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DOI：
10.1121/1.418119
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发表时间：
1997-01-01
影响因子：
2.4
通讯作者：
Miller, JG
中科院分区：
文献类型：
--
作者：
Hall, CS;Verdonk, ED;Miller, JG
测量的频率依赖性的超声背向散射提出了特定角度的声穿透区域的梗死和非梗死的人类心肌。用5 MHz换能器对6例因缺血性心肌病而经福尔马林固定的人心脏左室游离壁7个非梗塞区和12个梗塞区的圆柱形心芯进行声穿透。表观（未补偿衍射效应和衰减）后向散射对频率的依赖关系近似为幂律依赖关系，\B（f）\（2）= af（n）。在无损耗介质中的理想条件下，不补偿衍射和衰减效应的效果导致瑞利散射体的n值为2.0，而完全补偿后向散射系数的频率依赖性为f（4）。在3-7 MHz的频率范围内测定n值。非梗死和梗死心肌表现出各向异性的背向散射的频率依赖性，最大值发生在垂直于主要肌纤维方向和最小值时，平行于纤维的角度。周向超声辐照对非梗死心肌的结果为1.8 ± 0.1，对梗死心肌的结果为1.2 ± 0.1，而平行超声辐照对非梗死心肌的结果为0.4 ± 0.1，对梗死心肌的结果为0.0 ± 0.1。非梗死和梗死心肌的角度依赖性背向散射的功能形式是相似的，虽然频率依赖性是明显不同的两种组织状态的所有角度的声穿透。这项研究的结果表明，各向异性的频率依赖性的背向散射可能发挥了重要的作用，在超声成像，是一个重要的考虑超声组织定征在心肌。(C)1997年美国声学学会。
Measurements of the frequency dependence of ultrasonic backscatter are presented for specific angles of insonification for regions of infarcted and noninfarcted human myocardium. A 5-MHz transducer was used to insonify cylindrical cores taken from 7 noninfarcted regions and 12 infarcted regions of the left ventricular free wall of 6 formalin-fixed human hearts explanted because of ischemic cardiomyopathy. The dependence of apparent (uncompensated for diffraction effects and attenuation) backscatter on frequency was approximated by a power-law dependence, \B(f)\(2) = af(n). Under ideal conditions in a lossless medium, the effect of not compensating for the effects of diffraction and attenuation leads to the value of n to be 2.0 for Rayleigh scatterers while the frequency dependence of the fully compensated backscatter coefficient would be f(4). The value of n was determined over the frequency range, 3-7 MHz. Both noninfarcted and infarcted myocardium exhibited anisotropy of the frequency dependence of backscatter, with maxima occurring at angles that were perpendicular to the predominant myofiber direction and minima when parallel to the fibers. Perpendicular insonification yielded results for it of 1.8+/-0.1 for noninfarcted myocardium and 1.2+/-0.1 for infarcted myocardium while parallel insonification yielded results of 0.4+/-0.1 for noninfarcted and 0.0+/-0.1 for infarcted myocardium. The functional form of the angle-dependent backscatter is similar for both noninfarcted and infarcted myocardium, although the frequency dependence is clearly different for both tissue states for all angles of insonification. The results of this study indicate that the anisotropy of the frequency dependence of backscatter may play a significant role in ultrasonic imaging and is an important consideration for ultrasonic tissue characterization in myocardium. (C) 1997 Acoustical Society of America.