经颅彩色双功能超声成像是检测脑血管疾病的重要手段，但由于颅骨对超声波的显著衰减，限制了系统的穿透力，降低了检测的成功率和准确性。而且这种非线性衰减会使回波增益补偿很难处理。同时超声波在颅骨与脑组织内传播的速度差异会影响声束合成的处理，并直接影响系统的距离分辨力。 本项目将针对颅内的特殊成像环境，重点解决经颅彩色双功能超声成像穿透力不足的关键科学问题。秉承时间换能量的研究思路，将编码扩谱方法引入经颅彩色双功能超声的研究中，在保证距离分辨力的前提下，作为提高穿透力的主要研究手段。同时对颅骨的存在所造成的回波增益补偿困难和声束合成影响，提出相应的、有效的自适应算法。为了使研究结果更具实用性，实验中采用由真实颅骨制作的颅内血流成像仿体。 通过本项目的研究，期望提高超声系统的信噪比或分辨力等指标，进而提高脑血管疾病的检测水平。同时为医学超声系统中微弱信号检测提供研究思路与方法。

Transcranial color-coded duplex sonography is an important means to detect cerebrovascular disease. But the skull makes ultrasonic generating significant attenuation, which limits the penetration of the system and reduces the success rate and accuracy of the detection. And the nonlinear attenuation make echo gain compensation difficult to deal with. Ultrasonic propagation speed difference within the skull and brain tissue will affect the beamforming, and directly affect the range resolution of the system. For intracranial special imaging environment, the project will address the lack of penetration of transcranial color-coded duplex sonography as a research focus. Adhering to the time-for-energy research ideas, coded spread spectrum method is introduced in the study of transcranial color-coded duplex sonography. Under the premise that the range resolution is not reduced, the method is proposed as the primary research means to improve penetration. The corresponding effective adaptive algorithms is provided to solve the echo gain compensation problem and beamforming error due to the existence of the skull. Finally, in order to make the results more practical, intracranial blood flow imaging phantom used in the experiment is made by real skull. The project is expected to improve the signal-to-noise ratio or resolution of the ultrasound system, thereby increasing the level of detection of cerebrovascular disease. At the same time the project is expected to provide ideas and methods for the foundation of weak signal detection of medical ultrasound systems.