title: Statistics of boundaries in ultrasonic B-scan images.
abstract: The existence of edges and boundaries in regions of interest (ROIs) in B-scan images alters the statistics of the backscattered echo from the ROI. Boundaries are the result of at least two different types of scattering scenarios in tissue, and the Nakagami model, which is being used extensively in ultrasound, is unlikely to fit the statistics of the backscattered echo under these conditions. Furthermore, there are very few other statistical models exist that describe the statistics of the backscattered echo from regions containing boundaries. In this work, the gamma mixture density and the recently proposed McKay density are explored as two viable models to fill this void. Justifications of these models are presented along with methods for estimating their parameters. Random number simulations and studies on tissue-mimicking phantoms indicate that the McKay and gamma mixture densities are the best for the modeling of the backscattered echo intensity when boundaries are present in the regions of interest.
authors.affiliation: Department of Electrical & Computer Engineering, Drexel University, Philadelphia, Pennsylvania, USA. Electronic address: pshankar@coe.drexel.edu.
authors.forename: P Mohana
authors.initials: PM
authors.lastname: Shankar
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D003627:Data Interpretation, Statistical; D019220:High-Energy Shock Waves; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D015233:Models, Statistical; D015203:Reproducibility of Results; D012542:Scattering, Radiation; D012680:Sensitivity and Specificity; D014463:Ultrasonography / Q000379:methods*
keywords: Edges and boundaries; Gamma density; Gamma mixture; Gamma sum; McKay density; Microcalcifications; Nakagami density; Phantoms; Speckle factor; Ultrasonic tissue characterization