Revised amplitude modulation for contrast-enhanced ultrasound imaging with a cMUT array

Over the past 15 years, capacitive micro-machined ultrasonic transducers (cMUT) have been developed as a promising alternative to standard piezoelectric transducer (PZT). A large bandwidth and a reduction in self-heating are among the main advantages of this high potential technology but it suffers from a high intrinsic nonlinearity. This behavior could lead to misclassification of tissue in ultrasound contrast-enhanced imaging. Classical sequences, such as Pulse Inversion (PI) or Amplitude Modulation (AM) are no longer suitable and the only solution seems to be the compensation of the cMUT nonlinearity by sending a pre-compensated waveform. In this work, we show that an alternative sequence to amplitude modulation mode (already used with PZT arrays) can be successfully applied with a cMUT probe without any limitation related to the nonlinearity of the transmitter.