医学超声谐波成像技术研究进展

对目前所采用的谐波成像技术作了简要的叙述，并探讨了应用前景。由于在组织和造影剂成像中利用了谐波频率，明显地改善了超声图像质量。超声中的谐波是由组织和造影剂产生。造影谐波来源于所注入的造影剂对超声的反射，与组织的反射无关。当不使用造影剂时，谐波是由非线性传播产生的。组织和造影剂的谐波成像在图像分辨力和对比度之间的折衷使得非线性信号大打折扣。

The technical progress of medical ultrasonic harmonic imaging

Medical ultrasound scanners are widely used in hospitals all over the world for diagnostic purposes.While many technological improvements have been achieved over the years that resulted in better images,a large number of patients are still difficult to image due to inhomogeneous skin layers and limited penetration.In recent years,harmonic frenquency is adopted in tissue imaging and contrast agents imaging,which improves the image quality.Harmonics in ultrasound are generated by tissue or by contrast agents.Contrast-agent harmonics are generated by reflections from the injected contrast agent and not from reflections from tissue.When no contrast is employed,harmonics are generated by tissue itself as a result of nonlinear propagation.Harmonic imaging of tissues or contrast agent forces an inherent compromise between image resolution and contrast that limits its sensitivity to nonlinear signals.This paper describes the technical progress of harmonic imaging briefly.Its clinical application prospect has been discussed also.