Temperature dependence of ultrasonic backscattered energy in motion-compensated images
Temperature dependence of ultrasonic backscattered energy in motion-compensated images
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DOI：
10.1109/tuffc.2005.1561620
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发表时间：
2005-10-01
影响因子：
3.6
通讯作者：
Moros, EG
中科院分区：
文献类型：
--
作者：
Arthur, RM;Trobaugh, JW;Moros, EG
非侵入性温度成像将增强在治疗水平上均匀加热肿瘤的能力。超声是用于此目的的有吸引力的模态。以前，我们预测的单调变化的背散射能量（CBE）的超声与温度的某些亚波长散射体。我们还测量了CBE值类似于我们的预测在牛肝，火鸡胸脯肉，猪肉在一个维度（1-D）。这些测量值被手动校正为回波信号的轴向位置随温度的变化。为了研究温度对二维CBE的影响，我们在水浴加热过程中对1厘米厚的牛肝、火鸡胸和猪肉样本进行成像。通过具有7 MHz线性探针的相控阵成像仪形成图像。使用射频（RF）信号允许使用互相关作为一个相似性的措施，自动跟踪功能位移作为温度的函数。整个样本的特征位移是不均匀的，轴向和侧向的典型总位移为0.5 mm。从37 ℃到50 ℃，以0.5 ℃的步长跟踪每个样本中8个图像区域的明显运动。找到运动补偿图像区域的包络，然后在每个像素处形成反向散射能量之前用3 X 3运行平均滤波器进行平滑。我们对CBE的测量比较了背散射能量（BE）图像中的正变化和负变化。CBE是单调的，并且在50 ℃时与其在37 ℃时的值相差约4dB。小于1 cm（3）的组织体积的相对无噪声CBE曲线支持使用CBE进行温度估计。
Noninvasive temperature imaging would enhance the ability to uniformly heat tumors at therapeutic levels. Ultrasound is an attractive modality for this purpose. Previously, we predicted monotonic changes in backscattered energy (CBE) of ultrasound with temperature for certain subwavelength scatterers. We also measured CBE values similar to our predictions in bovine liver, turkey breast, and pork muscle in one dimension (1-D). Those measurements were corrected manually for changes in the axial position of echo signals with temperature. To investigate the effect of temperature on CBE in 2-D, we imaged 1-cm thick samples of bovine liver, turkey breast, and pork muscle during heating in a water bath. Images were formed by a phased-array imager with a 7 MHz linear probe. Using radio frequency (RF) signals permitted the use of cross correlation as a similarity measure for automatic tracking of feature displacement as a function of temperature. Feature displacement across the specimen was nonuniform with typical total displacements of 0.5 mm in both axial and lateral directions. Apparent movement in eight image regions in each specimen was tracked from 37 to 50 degrees C in 0.5 degrees C steps. Envelopes of motion-compensated image regions were found then smoothed with a 3 x 3 running average filter before forming the backscattered energy at each pixel. Our measure of CBE compared means of both the positive and negative changes in the backscattered energy (BE) images. CBE was monotonic and differed by about 4 dB at 50 degrees C from its value at 37 degrees C. Relatively noise-free CBE curves from tissue volumes of less than 1 cm(3) supports the use of CBE for temperature estimation.