Speckle Noise Reduction Techniques in Ultrasound Imaging: A comprehensive review of the last two decades (2005-2024).

Ultrasound imaging has become a widely used medical modality over the past few decades. Despite technological advances, ultrasound images are susceptible to inherent noise that arises from tissue inhomogeneities and other acquisition-related uncertainties. The presence of noise degrades image quality and impacts diagnostic accuracy, necessitating the development of effective denoising techniques. In ultrasound denoising, the preservation of important structural information while reducing noise poses a significant challenge. Therefore, various techniques have been presented to enhance the quality of ultrasound images, each method having its own assumptions, strengths, and limitations. In this study, a comprehensive survey of significant work on ultrasound image denoising was presented. Understanding the nature of noise in ultrasound images and selecting an appropriate denoising method tailored to specific needs can be challenging for researchers. To address these challenges, basics of ultrasound imaging, including the characteristics of noise in ultrasound images, is clearly explained in this paper. This study involved a comprehensive search across six digital databases, considering studies published over the last two decades, up to 2024. Initially, 538 studies were identified. From these, 85 studies were selected for detailed examination. For these 85 studies, we used snowballing and direct searches to locate additional relevant publications by the researchers and their associated research groups. Ultimately, we reviewed a total of 97 studies focusing on speckle noise reduction in ultrasound imaging. In addition, the merits and drawbacks of existing methods are analyzed and tabulated.