System and method for ultrasound perfusion imaging

A method of obtaining an ultrasound perfusion image of tissues perfused with blood containing microbubbles, the method comprising:

• transmitting a broad beam of microbubble-destroying ultrasound into the tissues, the beam of microbubble-destroying ultrasound encompassing a first area of the tissues, the microbubble-destroying ultrasound having an intensity that is sufficient to destroy microbubbles in the tissues that are insonified by the microbubble-destroying ultrasound;
• repetitively transmitting a plurality of beams of imaging ultrasound into the tissues, each beam of imaging ultrasound having a second area that is smaller than the first area, the imaging ultrasound having an intensity that is substantially insufficient to destroy microbubbles in the tissues that are insonified by the imaging ultrasound;
• receiving reflections from each of the transmitted imaging ultrasound beams in respective receive beams, each of the receive beams having a third area that is smaller than the first area;
• and
• processing the received reflections over a sufficient period to allow re-perfusion of the tissues to provide an ultrasound perfusion image
• wherein the act of transmitting a broad beam of microbubble-destroying ultrasound into the tissues comprises sequentially transmitting beams of microbubble-destroying ultrasound at a rate that is sufficiently high that subsequent beams are transmitted before a previously transmitted beam of microbubble-destroying ultrasound has been fully reflected from the tissues.

A method of obtaining an ultrasound perfusion image of tissues perfused with blood containing microbubbles, the method comprising:

• using ultrasound to simultaneously destroy substantially all of the microbubbles in the tissues over a first area;
• and
• repetitively using ultrasound transmitted and received in a plurality of second areas that substantially encompasses the first area to obtain an indication of the quantity of microbubbles in the tissues that are intact over a re-perfusion time, each of the second areas being smaller than the first area,
• wherein the act of using ultrasound to simultaneously destroy substantially all of the microbubbles in the tissues over a first area comprises using a plane-wave beam of ultrasound to simultaneously destroy substantially all of the microbubbles in the tissues over the first area.