Ultrasound imaging by nonlinear localization
Nonlinear ultrasound imaging systems and methods are disclose. In one aspect, a nonlinear ultrasound imaging system includes a first transducer configured to transmit a first ultrasound signal along a scan line, a second transducer configured to sweep a second ultrasound signal along the scan line such that the first and second ultrasound signals intersect at a plurality of voxels, and a third transducer configured to receive echoes associated with interactions of the first and second ultrasound signals at the plurality of voxels. The nonlinear ultrasound imaging system further includes a processor configured to generate an ultrasound image based on the echoes.
1. A method of nonlinear ultrasound imaging, the method comprising:
transmitting a first ultrasound beam centered at a first frequency along a scan line;
transmitting a second ultrasound beam centered at a second frequency, wherein transmitting the second ultrasound beam comprises sweeping the position of the second ultrasound beam in a direction such that the second ultrasound beam intersects with the first ultrasound beam at a plurality of voxels along the scan line, wherein the second frequency is different than the first frequency;
receiving echoes associated with interaction of the first ultrasound beam and the second ultrasound beam at the plurality of voxels along the scan line; and
generating an ultrasound image based on the received echoes.
2. The method of claim 1 , wherein the first ultrasound beam is transmitted with a first transducer, and
wherein the second ultrasound beam is transmitted with a second transducer, different than the first transducer.
3. The method of claim 2 , wherein the second transducer comprises a phased array of ultrasound transducers that performs the sweeping by at least beam steering the position of the second ultrasound beam.
4. The method of claim 1 , wherein the echoes associated with interaction of the first ultrasound beam and the second ultrasound beam are received with a third transducer.
5. The method of claim 4 , wherein the echoes are each centered at a respective third frequency based on the first frequency of the first ultrasound beam and the respective second frequency of the second ultrasound beam.
6. The method of claim 5 , wherein the third frequency corresponds to a difference between the first frequency of the first ultrasound beam and the second frequency of the second ultrasound beam.
7. The method of claim 4 , wherein the third transducer is scanned during the receiving of the echoes in order to focus on the respective voxels.
8. The method of claim 7 , wherein the third transducer is scanned by moving the third transducer.
9. The method of claim 7 , wherein the third transducer is scanned through beam steering.
10. The method of claim 1 , wherein the first ultrasound beam and the second ultrasound beam intersect at different angles, each approximately 90 degrees, at each of the plurality of voxels.
11. The method of claim 1 , wherein the first ultrasound beam and the second ultrasound beam intersect at a 40 degree angle at one of the plurality of voxels.
12. The method of claim 1 , wherein the first ultrasound beam and the second ultrasound beam intersect at a 140 degree angle at one of the plurality of voxels.
13. The method of claim 1 , further comprising frequency modulating at least one of the first ultrasound beam and second ultrasound beam among discrete frequencies during the sweeping.
14. The method of claim 1 , wherein generating the ultrasound image comprises frequency compounding.
15. The method of claim 14 , wherein generating the ultrasound image further comprises spatial compounding.