Ultrasound Image Denoising by Spatially Varying Frequency Compounding

Abstract

Abstract. Ultrasound images are very noisy. Along with system noise, a significant noise source is the speckle phenomenon, caused by interference in the viewed object. Most past approaches for denoising ultrasound images essentially blur the image, and they do not handle attenuation. Our approach, on the contrary, does not blur the image and does handle attenuation. Our denoising approach is based on frequency compounding, in which images of the same object are acquired in different acoustic frequencies, and then compounded. Existing frequency compounding methods have been based on simple averaging, and have achieved only limited enhancement. The reason is that the statistical and physical characteristics of the signal and noise vary with depth, and the noise is correlated. Hence, we suggest a spatially varying frequency compounding, based on understanding of these characteristics. Our method suppresses the various noise sources and recovers attenuated objects, while maintaining high resolution.

Variational Distance-Dependent Image Restoration

“…Important features, such as texture for the close fields and edges for the distant mountains are pre- 6 Acknowledgements to G. Peyre for implementing the algorithm and making it available via the MATLAB File Exchange. 7 The object radiance of pixels where λ ≈ a ∞ λ cannot be restored. Therefore, they were replaced by the noisy restoration of the path radiance.…”

“…5 using Eqs. (7,8) and (9). The restoration is noisy, especially in pixels corresponding to the distant mountain.…”

“…Attention is increasingly being directed towards imaging through scattering and attenuating media, such as haze [5,13,15,18,23], water [9,12,14,16,21,22,27] and tissue [6,7]. It is important to overcome image degradation problems associated with such media.…”

A Modified Method for Speckle Noise Removal in Ultrasound Medical Images

“…A speckle does not have a regular shape [15]. It is not appropriate to use predefined structuring elements like disk, rectangle, hexagon etc., for morphological processing [9] [19]. Therefore an arbitrary structuring element which resembles the speckle shape is designed.…”

Mejora en la calidad de imágenes ultrasónicas aplicando métodos de composición espacial y empleando sistemas de Phased Array

“…Trabajos posteriores obtuvieron mejoras en la relación señal ruido (SNR) [12] y reducción de artefactos inherentes al US [13]. Existen, además, estudios de composición espacial tridimensional y angular [14], [15] y otros donde la composición de imágenes fue desarrollada exclusivamente en el dominio de la frecuencia [16], [17], estos lograron resultados con mejoras en la SNR y en el contraste de las imágenes obtenidas.…”