The combined effect of spatial compounding and nonlinear filtering on the speckle reduction in ultrasound images.

Recently, a spatial compounding ultrasound imaging method was presented that utilizes a conventional 64-element phased array transducer with two unfocused pistons, each placed at one of the sides of the phased array transducer. This method is augmented here by inclusion of nonlinear filtering of the compounded images. The combined effects of the specific spatial compounding and nonlinear filtering on speckle reduction in the generated ultrasound images are studied and evaluated in two stages: First, the image quality is studied when nonlinear filtering is used as part of the spatial compounding. The study is performed by simulations using the Field II program, by processing several B-mode images of a kidney. The second stage compares the results obtained by the simulations to those obtained by in vitro laboratory experiments. Five different compounding strategies and two nonlinear filters, Gaussian and anisotropic diffusion, are investigated and evaluated in terms of image quality parameters-contrast and signal-to-noise ratio. It is shown that the combination of "averaging+nonlinear Gaussian filtering" produces the greatest improvement of image quality. When compared to a conventional phased array imaging system, the spatial compounding method that includes the conventional 64-element phased array transducer with two unfocused pistons, and employs the "averaging+nonlinear Gaussian filtering" strategy, obtains improvement in SNR that has reached 334%. Thus, though this method necessitates a somewhat wider probe, it produces significantly improved images.

[1]  Patrick J. Flynn,et al.  Regular ArticlePhase Insensitive Homomorphic Image Processing for Speckle Reduction , 1996 .

[2]  F. T. ten Cate,et al.  Super harmonic imaging: a new imaging technique for improved contrast detection. , 2002, Ultrasound in medicine & biology.

[3]  Partially coherent transducers: the random phase transducer approach. , 1990, Ultrasonic imaging.

[4]  Ian T. Young,et al.  Fundamentals of Image Processing , 1998 .

[5]  S.W. Smith,et al.  Speckle Pattern Correlation with Lateral Aperture Translation: Experimental Results and Implications for Spatial Compounding , 1986, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[6]  Chunhui Zhao,et al.  Noise attenuation characteristics of generalized morphological filters , 1998, Other Conferences.

[7]  R. F. Wagner,et al.  Properties of Acoustical Speckle in the Presence of Phase Aberration Part II: Correlation Lengths , 1988, Ultrasonic imaging.

[8]  Scott T. Acton,et al.  Speckle reducing anisotropic diffusion , 2002, IEEE Trans. Image Process..

[9]  Mark S. Nixon,et al.  Biased motion-adaptive temporal filtering for speckle reduction in echocardiography , 1996, IEEE Trans. Medical Imaging.

[10]  Jörg Weule,et al.  Non-Linear Gaussian Filters Performing Edge Preserving Diffusion , 1995, DAGM-Symposium.

[11]  A. Winder,et al.  Multi-frequency harmonic arrays: initial experience with a novel transducer concept for nonlinear contrast imaging. , 2004, Ultrasonics.

[12]  Zvi Friedman,et al.  A new method of spatial compounding imaging. , 2003, Ultrasonics.

[13]  Albert Macovski,et al.  Lesion contrast enhancement in medical ultrasound imaging , 1997, IEEE Transactions on Medical Imaging.

[14]  S. K. Jespersen,et al.  Multi-Angle Compound Imaging , 1998, Ultrasonic imaging.

[15]  Ruey-Feng Chang,et al.  Automatic ultrasound segmentation and morphology based diagnosis of solid breast tumors , 2004, Breast Cancer Research and Treatment.

[16]  M. Giger,et al.  Computerized analysis of shadowing on breast ultrasound for improved lesion detection. , 2003, Medical physics.

[17]  Y Chen,et al.  Phase insensitive homomorphic image processing for speckle reduction. , 1996, Ultrasonic imaging.

[18]  K. Boone,et al.  Effect of skin impedance on image quality and variability in electrical impedance tomography: a model study , 1996, Medical and Biological Engineering and Computing.