An ultrasound imaging system with pixel oriented processing is provided in which an acoustic signal is generated, echoes from the acoustic signal are received at a plurality of receiving elements to obtain echo signals that are then stored, a given pixel is mapped into a region of the stored signals, the mapped region of the stored echo signals is organized into array for the given pixel after which the array is processed to generate a signal response for the given pixel to obtain acoustic information for the given pixel. The system can be implemented entirely on plug-in cards for a commercial PC motherboard. The system and method can be implemented for pixel-oriented or voxel-oriented image processing and display, eliminating intermediate data computations and enabling extensive use of software processing methods. Advantages include improved acquisition of signal dynamic range, flexible acquisition modes for high frame rate 2D, 3D, and Doppler blood flow imaging.