Methods for the detection of contrast agents in ultrasonic imaging

Abstract

Quadrature demodulation apparatus and method for detecting a contrast agent in an ultrasonic echographic system, including an in phase/quadrature demodulator for determining the resolved complex real and imaginary in phase and quadrature components of return signals and a contrast agent detector determining the complex difference between first and second return signals. The detector is implemented as a magnitude of difference detector determining the magnitude of the complex difference of pairs of first and second return signals wherein the real and imaginary components of the return signals, including magnitude and phase information, are used to determine the magnitude of the complex difference between first and second return signals. The detector is also implemented as an asymmetrical weighting detector resolving the complex difference between first and second return signals into components in phase with and orthogonal to the second signal and weighting the magnitudes of in phase and orthogonal components of the complex difference and indicating a contrast agent present when the combination of differently weighted component exceeds the corresponding threshold value. The detector is also implemented as an extrapolation detector for receiving three successive return signals along each line wherein the second return signal and a third return signal are used to extrapolate what the first return signal would have been without the contrast agent component and to generate a decision threshold that is compared to the complex difference between the actual first return signal and the extrapolated first return signal.