Ultrasound contrast agents to enhance and monitor therapy

New techniques for the assessment of tissue perfusion and the local delivery of drugs have been developed using ultrasound contrast agents. A perfusion estimator, based on the destruction and wash‐in of ultrasound contrast agents, has been developed and applied to tumor models. This technique requires the transmission of a train of pulses with varying amplitude, frequency, and phase within the train. High‐amplitude and low‐frequency pulses are applied to destroy the agent, and low‐amplitude higher‐frequency pulses are used to monitor the refresh of contrast agents into the sample volume. The signal processing techniques applied following data acquisition utilize the subharmonic component of the received signal. Mechanistic studies of contrast agent destruction, a Rayleigh–Plesset based signal model, and experimental data acquired from a rat tumor model will be included in our presentation. In addition, studies of the local delivery of drugs using oil‐based drug delivery vehicles have been conducted. Resul...