Phase-coded pulse sequence for non-linear imaging

Nonlinear imaging modes are of great interest for perfusion imaging with contrast agents and for tissue harmonic imaging, i. e. a technique that provides improved spatial and contrast resolution. For both applications, many tradeoffs have to be made concerning transmit power, imaging depth, resolution, frame rate etc. because of the non-linear nature of the effects used for imaging. Time domain and spatial domain phase inversion (pulse inversion) techniques have been successfully introduced. Longer pulse sequences in combination with phase inversion allow for lower acoustic peak intensities or higher penetration depth. However, phase inversion eliminates all spectral components that are related to odd order non-linearities. We propose a phase-coded 5-pulse sequence that overcomes this limitation while providing the desired increase in SNR.