子阵列差分系数加权的超声成像算法

传统的自适应加权系数可以有效改善超声图像的分辨率和对比度,但会影响背景图像的散斑特性,因此提出子阵列差分加权系数(SDF)以提升图像质量。该系数适用于传统线扫描超声成像,首先对阵列接收到的回波信号采用子阵列平滑的方式计算均值,得到信号中高相干性成份的强度,再用差分的方式反映相邻阵元回波信号之间的差异性,最后对延时叠加(DAS)成像结果进行加权成像。仿真和实验结果表明SDF (L=8)加权算法相对于传统的DAS成像算法,可以有效改善分辨率和对比度,其中仿真数据的对比度提高了62.9%,体模实验数据的对比度提高了74.7%。相对于相干系数(CF)、广义相干系数(GCF)和信号均值标准差系数(SMSF),SDF可以改善背景组织的成像质量,其中仿真图像的散斑信噪比(SSNR)分别提高了36.8%,5.7%和26.2%,体模实验图像的SSNR分别提高了48.6%,17.0%和20.9%。可见SDF系数可以有效改善超声成像的质量。

Ultrasound imaging weighted by subarray differential factor

Traditional adaptive weighting factor can improve the resolution and contrast of ultrasound images,but speckle pattern of background image is broken.Therefore,Subarray Difference Factor(SDF) was proposed to improve the image quality.The factor is used for conventional line-scan ultrasound imaging.It applies the subarray smoothing on the echo signals received by the transducer array to obtain mean values which can represent the intensity of high coherence components.Then,the difference is used to get the differences of the echo signals received by adjacent elements.Finally,SDF is used to weight the Delay And Sum(DAS) output.Simulation and phantom experimental results indicate that SDF(L=8) can improve resolution and yield improvements of 62.9% and 74.7% in contrast ratio,respectively,compared with the DAS beamformer.In comparison with Coherence Factor(CF),Generalized Coherence Factor(GCF),and signal mean-to-standard-deviation factor(SMSF),SDF generates a better background speckle quality with Speckle Signal-to-Noise Ratio(SSNR) improvements of 36.8%,5.7%,26.2% in simulation,and 48.6%,17.0%,20.9% in phantom experiment,respectively.This indicates the effectiveness of the SDF to improve ultrasound image quality.