Pre-envelope deconvolution for increased lesion detection efficiency in ultrasonic imaging

We use an ideal observer model to evaluate the efficiency of human observers detecting a simulated lesion in the presence of speckle, and the ability of pre-envelope deconvolution to improve performance in this task. We model the lesion as a localized area of increased scatter density, which translates into an area of higher variance in the ultrasound signal. Assuming the scattering function and electronic noise obey Gaussian distributions, the ideal observer for lesion detection is given by a quadratic function of the in-phase (I) and quadrature (Q) data. For comparison, human-observer performance is assessed through two-alternative forced-choice (2AFC) psychophysical studies after making a B-mode image by computing the magnitude (envelope) of the I and Q components. We also consider the effect of removing spatial correlations in the I and Q components, before computing the magnitude (pre-envelope deconvolution). Our Psychophysical studies indicate approximately a 4-fold improvement in detection efficiency with pre-envelope deconvolution.