血管内光声图像的时间反演重建方法

Time-reversal based reconstruction of intravascular photoacoustic images

目的将光声成像与医学内窥技术相结合的血管内光声(IVPA)成像技术可为心血管内易损斑块的检测以及指导介入治疗提供可靠的参考。针对采用单阵元探测器进行圆周扫描的IVPA成像系统,提出基于时间反演(TR)算法的重建IVPA横截面灰阶图像的方法。方法通过建立超声传播模型,对光声信号的反向传播过程进行模拟,反演得到血管横截面的2维初始光声压分布图像。针对测量位置稀疏和有限角度测量都会造成光声数据不完备,进而导致重建图像质量下降的问题,通过对探测器采集到的光声信号进行样条插值达到提高成像质量以及消除伪影的目的。结果仿真实验结果表明,与相同测量位置下利用滤波反投影(FBP)算法重建出的图像相比,采用本文算法重建出的图像的结构相似性指标(SSIM)值可提高约65%。结论该方法能有效地提高IVPA重建图像的质量,为后续图像重建算法的优化提供有益参考。

Objective Intravascular photoacoustic （IVPA） imaging combines photoacoustic imaging and medical endoscopic technique. It provides reliable information on cardiac vessels and atherosclerotic plaques for the detection of vulnerable plaques and interventional treatment of cardiac diseases. A method of reconstructing cross-sectional gray-scale images based on the time-reversal algorithm is proposed for the IVPA imaging system equipped with a single ultrasonic detector with cir- cular scanning. Method The back-propagation of photoacoustic waves generated by the vascular tissues is modeled and nu- merically simulated to obtain 2D images of photoacoustic pressure distribution. The photoacoustic signals collected by the ultrasonic detector are interpolated to solve the problem of incomplete photoacoustic data caused by sparse measuring posi- tions and limited-view measurement. Result The results of computer-simulated experiments suggest that the structural simi- larity of the reconstructed images is at least 65% higher than that of images obtained with the filtered back-projection algo- rithm. Conclusion The proposed method can effectively improve the quality of the reconstructed image for IVPA imaging and can serve as a useful reference for subsequent optimization of image reconstruction algorithms.