《Linear System Models for Ultrasonic Imaging Application to Signal Statistics》.pdf

NIH Public Access Author Manuscript IEEE Trans Ultrason Ferroelectr Freq Control . Author manuscript; available in PMC 2010 March 4. N I H Published in final edited form as: - P IEEE Trans Ultrason Ferroelectr Freq Control . 2003 June ; 50(6): 642–654. A A u Linear System Models for Ultrasonic Imaging: Application to t h o r Signal Statistics M a n u Roger J. Zemp, Craig K. Abbey, and Michael F. Insana s c The authors are with the Department of Biomedical Engineering, University of California, Davis CA r i p 95616 t Roger J. Zemp: ; Craig K. Abbey: ; Michael F. Insana: mfinsana@ucdavis.edu Abstract Linear equations for modeling echo signals from shift-variant systems forming ultrasonic B-mode, Doppler, and strain images are analyzed and extended. The approach is based on a solution to the N homogeneous wave equation for random inhomogeneous media. When the system is shift-variant, I H the spatial sensitivity function—defined as a spatial weighting function that determines the scattering - volume for a fixed point of time—has advantages over the point-spread function traditionally used P A to analyze ultrasound systems. Spatial sensitivity functions are necessary for determining statistical A moments in the context of rigorous image quality assessment, and they are time-reversed copies of u t point-spread functions for shift variant systems. A criterion is proposed to assess the validity of a h o local shift-invariance assumption. The analysis reveals realistic situations in which in-phase signals r M are correlated t