Abstract: In view of inherent speckle noise in medical images,a de-speckling method was proposed based on an expectation maximization(EM) framework.Firstly,the real part was extracted from the Inphase/Quadrature(I/Q) ultrasound image.Then,the point spread function was blindly estimated from the real image.Lastly,based on the EM framework,an iterative algorithm alternating between Wiener filtering and anisotropic diffusion was exploited to produce de-speckled images.The comparison experiment was carried out on both simulated and in vitro ultrasound images using the proposed method and exited ones,respectively.It was shown that the proposed method averagely improved the speckle-signal-to-noise Ratio(S-SNR) and the edge preservation index(β) of I/Q images by the factor of 1.94 and 7.52.Meanwhile,it averagely reduced the normalized mean-squared error(NMSE) by the factor of 3.95.The simulation and in vitro results indicated that the proposed method had a better overall performance than exited ones.