Details

Autor(en) / Beteiligte

• Zemp, R.J.
• Abbey, C.K.
• Insana, M.F.

Titel

Linear system models for ultrasonic imaging: application to signal statistics

Ist Teil von

• IEEE transactions on ultrasonics, ferroelectrics, and frequency control, 2003-06, Vol.50 (6), p.642-654

Ort / Verlag

New York, NY: IEEE

Erscheinungsjahr

2003

Quelle

IEEE Electronic Library Online

Beschreibungen/Notizen

• 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 homogeneous wave equation for random inhomogeneous media. When the system is shift-variant, 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 to analyze ultrasound systems. Spatial sensitivity functions are necessary for determining statistical moments in the context of rigorous image quality assessment, and they are time-reversed copies of point-spread functions for shift variant systems. A criterion is proposed to assess the validity of a local shift-invariance assumption. The analysis reveals realistic situations in which in-phase signals are correlated to the corresponding quadrature signals, which has strong implications for assessing lesion detectability. Also revealed is an opportunity to enhance near- and far-field spatial resolution by matched filtering unfocused beams. The analysis connects several well-known approaches to modeling ultrasonic echo signals.