针对微波消融技术应用中的无创监测组织温度难题,通过B超原始射频信号重建B超图像,排除B超仪器的相关性,探讨了利用B超图像纹理特征实现热疗温度监测的可行性.通过水浴加热猪肝实验,采集不同温度下的猪肝B超射频信号,在此基础上重建B超图像并分析图像纹理特征参数(灰度直方图、灰度共生矩阵与灰度梯度共生矩阵)与温度的相关性.实验结果表明:组织B超图像纹理参数随着温度变化而变化,在20~60℃范围内灰度直方图中的灰度均值,灰度共生矩阵中的熵以及灰度梯度共生矩阵中的混合熵、逆差距、相关等5个参数与组织温度间具有较高的线性相关性,利用这5个参数可实现肿瘤微波消融治疗中组织温度的无创检测.
The noninvasive estimation of tissue temperature is a key problem in hyperthermia. The original ultrasonic RF signal was used to reconstruct B-mode images, eliminating device-dependent variances to explore the use of B-mode image texture parameters in monitoring temperature and coagulation zones in hyperthermia. The water bath heating experiments were carried out on in-vitro porcine liver samples, and the ultrasound RF signal at different temperatures was collected. Then the B- mode ultrasonic images were reconstructed, and the texture features (gray level histogram, gray level co- occurrence matrices, and gray level-gradient co-occurrence matrix) were extracted. The correlations between temperature and texture parameters of B-mode images were analyzed. Results indicate that some texture parameters are linearly correlated with the temperature in the heated tissue at a temperature from 20 ~C to 60 ~C. Five parameters with large correlations with temperatures include mean gray scale of gray level histogram, entropy of gray level co-occurrence matrix, and hybrid entropy, inverse difference and correlation of gray level-gradient co-occurrence matrix. These five texture features with large correlations with temperatures can be used for tissue temperature estimation in clinical microwave tumor ablation.