平面波经颅超声成像相位校正及散斑跟踪

Phase correction and speckle tracking in plane wave transcranial ultrasound imaging

准确的脑血流成像对脑功能监测和脑疾病的快速诊断具有重要意义,然而颅骨对超声传播的影响会导致成像质量下降、速度或位移估计不准确等问题。论文采用平面波相干复合结合散斑跟踪方法进行颅内散射目标成像和速度估计,以实现脑血流速度矢量检测;针对颅骨存在导致的超声相位畸变,利用数值仿真和体模实验研究了其对成像及散斑跟踪效果的影响,并采用近似射线声学理论方法进行校正。数值结果表明颅骨的存在造成目标运动速度估计的相对误差达到55%左右,校正后误差降至约12%;体模实验中对目标位移大小和角度估计的平均误差在校正前分别约为16%和28%,校正后均降至1%左右。该研究结果可为超声颅脑疾病诊疗设备的研制提供理论指导和技术支持。

Accurate cerebral blood flow imaging is of great significance for the monitoring of brain function and the rapid diagnosis of brain diseases.However,the influence of skull on ultrasonic transmission may lead to problems such as imaging quality decline,inaccurate estimation of velocity or displacement,etc.In this paper,imaging and velocity estimation of intracranial scattering targets were carried out by combining the coherent planewave compounding method with the speckle tracking method,thus to realize the detection of cerebral blood flow velocity vector.In view of the ultrasonic phase distortion caused by the presence of skull,the influence of the phase distortion on imaging and speckle tracking was studied by numerical simulation and phantom experiment,and an approximate phase compensating method based on acoustic ray theory was used.The numerical results show that the relative error of target velocity estimation is about 55%due to the presence of skull,and the error is reduced to about 12%after phase correction.In the phantom experiment,the average errors of target displacement size and angle estimation are about 16%and 28%respectively before correction,and both are reduced to about 1%after correction.The research results can provide theoretical guidance and technical support for the development of ultrasonic diagnosis and treatment equipment for craniocerebral diseases.