Development of a MRI-based Technique for Visualizing Ultrasound Field in Biological Tissue

到目前为止，超声场测量仅在水中使用水听器或光学方法进行。生物组织超声场的测量对于提高超声诊断和治疗的准确性具有重要意义，但目前尚无有效的测量方法。因此，本研究开发了一种基于mri的生物组织超声场可视化技术。为了使超声场可视化，利用磁共振成像仪测量了以安全超声强度施加声辐射力所引起的介质中的微小位移。为了获得清晰的超声场图像，研究了获取磁共振图像的脉冲序列和磁共振信号的信号处理方法。数值模拟和模拟实验结果表明，在采集和处理后的磁共振图像上，介质中的超声场可以被可视化。

So far, ultrasound field measurements have been conducted by using a hydrophone or optical method in only water. Although the measurement of ultrasound field in a biological tissue is important for improving accuracy in the ultrasound diagnosis and therapy, there was no effective method for such measurement technique. Therefore, a MRI-based technique for visualizing the ultrasound field in the biological tissue was developed in this study. In order to visualize the ultrasound field, minute displacements in a medium, which is induced by applying the acoustic radiation force with safety ultrasound intensity, were measured by using a MR imager. In order to obtain clear images of ultrasound field, pulse sequence for acquiring MR images and signal processing method of MR signals were investigated. Results of numerical simulation and phantom experiment revealed that the ultrasound field in the medium can be visualized on the acquired and processed MR images.