Ultrasonic diagnostic imaging systems with power modulation for contrast and harmonic imaging

• US 6,234,967 B1
• Filed: 12/18/1998
• Issued: 05/22/2001
• Est. Priority Date: 12/18/1998
• Status: Expired due to Fees

• Current Assignee: ATL Ultrasound Incorporated (Koninklijke Philips N.V.)
• Original Assignee: ATL Ultrasound Incorporated (Koninklijke Philips N.V.)
• Inventors: Powers, Jeffry E.
• Primary Examiner(s): Jaworski, Francis J.
• Application Number:
  US09/216,693
• Time in Patent Office: 886 Days
• Field of Search: 600/443, 600/440-442, 600/447, 600/437, 600/458
• US Class Current: 600/443
• CPC Class Codes: A61B 8/481 involving the use of contrast agent, e.g. microbubbles introduced into the bloodstream analysis of echo signal exploiting properties of a contrast enhancer in devices for short-range imaging with acoustic waves G01S7/52039
• CPC Class Codes: G01S 15/8927 using simultaneously or sequentially two or more subarrays or subapertures
• CPC Class Codes: G01S 7/52038 involving non-linear properties of the propagation medium or of the reflective target
• CPC Class Codes: G01S 7/52039 exploiting the non-linear response of a contrast enhancer, e.g. a contrast agent diagnostic techniques involving the use of contrast agents A61B8/481
• CPC Class Codes: G01S 7/52041 detecting modification of a contrast enhancer, e.g. detecting the destruction of a contrast agent by an acoustic wave, e.g. loss of correlation diagnostic techniques involving the use of contrast agents A61B8/481
• CPC Class Codes: G10K 11/341 Circuits therefor

Abstract

A method and ultrasonic diagnostic imaging system for contrast agent imaging or tissue harmonic imaging is described which modulates the transmit power as a function of the angle of an electronically steered beam or the location of the beam in the scan plane to compensate for the reduction in delivered energy to points in the image field resulting from off-angle steering or a reduction in the number of elements of the transmit aperture.

Claims

1. A method for ultrasonic diagnostic imaging of contrast agents with an array of transducer elements having a face surface opposing a target region and exhibiting a transmit aperture comprising the steps of:

applying a given level of transmit power to the elements of the transmit aperture when a beam is transmitted normal to the face surface of the array so as develop a desired mode of microbubble behavior at a target region at a given depth; and

applying a level of transmit power to the elements of the transmit aperture which is in excess of said given level when a beam is transmitted at an off-angle to the face surface of the array so as to develop substantially the same mode of microbubble behavior at a target region of equivalent depth.

2. The method of claim 1, wherein said transmit power is controlled so that said beams act to develop substantially the same ultrasonic harmonic effect at substantially uniform depths across an ultrasonic image.

3. The method of claim 2, wherein said desired ultrasonic harmonic effect comprises nonlinear oscillation of a microbubble.

4. The method of claim 2, wherein said desired ultrasonic harmonic effect comprises disruption of a microbubble.

5. The method of claim 1, wherein said transmit power is controlled so that said beams act to develop a desired ultrasonic harmonic effect at all depths of an ultrasonic image.

6. The method of claim 5, wherein said desired ultrasonic harmonic effect comprises nonlinear oscillation of a microbubble.

7. The method of claim 5, wherein said desired ultrasonic harmonic effect comprises disruption of a microbubble.

8. A method for ultrasonic diagnostic imaging of contrast agents with an array of transducer elements having a face surface opposing a target region and exhibiting a transmit aperture comprising the steps of:

applying a given level of transmit power to the elements of the transmit aperture when a beam is transmitted normal to the face surface of the array; and

applying progressively increasing levels of transmit power to the elements of the transmit aperture as beams are transmitted at increasingly acute angles to the face surface of the array.

9. The method of claim 8, wherein said transmit power is controlled so that said beams act to develop substantially the same ultrasonic harmonic effect at substantially uniform depths across an ultrasonic image.

10. The method of claim 9, wherein said desired ultrasonic harmonic effect comprises nonlinear oscillation of a microbubble.

11. The method of claim 9, wherein said desired ultrasonic harmonic effect comprises disruption of a microbubble.

12. The method of claim 8, wherein said transmit power is controlled so that said beams act to develop a desired ultrasonic harmonic effect at all depths of an ultrasonic image.

13. The method of claim 12, wherein said desired ultrasonic harmonic effect comprises nonlinear oscillation of a microbubble.

14. The method of claim 12, wherein said desired ultrasonic harmonic effect comprises disruption of a microbubble.

15. A method for using an array of ultrasonic transducer elements having a face surface opposing a target region and exhibiting a transmit aperture to perform tissue harmonic imaging comprising the steps of:

applying a given level of transmit power to the elements of the transmit aperture when a beam is transmitted normal to the face surface of the array so as develop a desired harmonic effect at a target region at a given depth; and

applying a level of transmit power to the elements of the transmit aperture which is in excess of said given level when a beam is transmitted at an off-angle to the face surface of the array so as to develop substantially the same harmonic effect at a target region of equivalent depth.

16. The method of claim 15, wherein the second step comprises applying progressively increasing levels of transmit power to the elements of the transmit aperture as beams are transmitted at increasingly acute angles to the face of the array.

17. The method of claim 15, wherein said transmit power is controlled so that said beams act to develop substantially the same level of harmonic signal content at substantially uniform depths across an ultrasonic image.

18. An ultrasonic diagnostic imaging system for imaging with contrast agents comprising:

an array transducer including a plurality of transducer elements; and

a transmitter coupled to individual elements of said array transducer which is adapted to apply levels of transmit power to said elements which vary as a function of the location of the transmit beam in the image plane so as to produce a more uniform harmonic effect at points in an image field of equivalent depth.

19. The ultrasonic diagnostic imaging system of claim 18, wherein said levels of transmit power applied by said transmitter are controlled to vary as a function of the lateral location of the transmit beam.

20. The ultrasonic diagnostic imaging system of claim 18, wherein said levels of transmit power applied by said transmitter are increased by said transmitter as the angle of the transmit beam to the face of the array transducer declines.

21. The ultrasonic diagnostic imaging system of claim 18, wherein said transmitter transmits a sector beam pattern, and wherein the level of transmit power applied to transmit a beam at the center of the sector is less than the level of transmit power applied to transmit a lateral beam of the sector.

22. The ultrasonic diagnostic imaging system of claim 18, wherein said transmitter acts to transmit a parallel beam pattern, and wherein the level of transmit power applied by said transmitter to transmit a beam varies as a function of the number of transducer elements of an active transmit aperture.

23. The ultrasonic diagnostic imaging system of claim 18, wherein said array transducer performs linear array scanning by using different active transmit apertures for different beams, and wherein said transmitter acts to apply increased levels of transmit power to said elements as the active transmit aperture approaches a lateral extreme of the array.

24. An ultrasonic diagnostic imaging system for performing tissue harmonic imaging comprising:

an array transducer including a plurality of transducer elements; and

a transmitter coupled to individual elements of said array transducer which applies levels of transmit power to said elements which vary as a function of the location of the transmit beam in the image plane so as to produce a more uniform harmonic effect at points in an image field of equivalent depth.

25. The ultrasonic diagnostic imaging system of claim 24, wherein said levels of transmit power are increased by said transmitter as the angle of the transmit beam to the face of the array transducer declines.

26. The ultrasonic diagnostic imaging system of claim 24, wherein said transmitter transmits a sector beam pattern, and wherein the level of transmit power used for a beam at the center of the sector is less than the level of transmit power used for a lateral beam of the sector.

27. An ultrasonic diagnostic imaging system for performing tissue harmonic imaging comprising:

an array transducer including a plurality of transducer elements which are used to form a plurality of active transmit apertures; and

a transmitter coupled to individual elements of said array transducer which applies levels of transmit power to said elements which vary as a function of the number of elements in the active transmit aperture so as to produce a more uniform harmonic effect at points in an image field of equivalent depth.