Methodological Approach to Reducing Speckle Noise in Ultrasound Images

This article investigates and compiles some of the techniques mostly used in the smoothing or suppression of speckle noise in ultrasound images. With this information, a comparison of all the methods studied is done based on an experiment, using quality metrics to test their performance and show the benefits each one can contribute. To test the methods, a synthetic, noise-free image is created and later applied well-known noise models to corrupt it. This way, the smoothing techniques can be compared using numeric metrics, taking the noise-free image as a reference. Since realultrasound images are already noise corrupted images and real noise-free images do not exist, conventional metrics cannot be used to indicate the quality obtained with filtering. Nevertheless, we propose the use of the tendencies observed in our study in real images.

1. Introduction

Medical images, such as magnetic resonance, x-rays, ultrasound, etc. are very useful tools for the diagnosis and study of various illnesses. Since the birth of Computer Science this science has been a great help for Medicine in general and in particular in the medical image field. This paper focuses on ultrasound images and specifically on speckle noise suppression. Ultrasound images are degraded by an intrinsic artefact called “speckle”, which is the result of the constructive and destructive coherent summation of ultrasound echoes.