Detecting a relative level of an ultrasound imaging contrast agent

• US 6,398,735 B1
• Filed: 03/07/2000
• Issued: 06/04/2002
• Est. Priority Date: 03/07/2000
• Status: Expired due to Fees

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Clark, David W
• Primary Examiner(s): Lateef, Marvin M.
• Assistant Examiner(s): Imam, Ali M.
• Application Number:
  US09/519,700
• Time in Patent Office: 819 Days
• Field of Search: 600/437, 600/440, 600/443, 600/447, 600/453, 600/458, 600/454, 600/420, 424/9.4, 424/9.6, 424/9.51, 424/9.52
• US Class Current: 600/458
• CPC Class Codes: A61B 8/06 Measuring blood flow measuring volume flow in general G01F, e.g. G01F1/66, G01F1/72; measuring speed of fluids in general G01P5/00
• 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

Abstract

A method for detecting a relative level of a contrast agent in a region of a body, where the contrast agent is susceptible to destruction by a destructive ultrasound signal. The method comprises the steps of: determining a signal level from a first ultrasound echo that is produced in the region during a first time, which occurs while the contrast agent is present in the region; determining a signal level of a second ultrasound echo that is produced in the region during a second time, which occurs after destruction of the contrast agent; and determining a ratio of the signal level from the first ultrasound echo and the signal level from the second ultrasound echo, where the ratio indicates a relative level of the contrast agent during the second time as compared to the first time.

Claims

1. A method for detecting a relative level of a contrast agent within a selected region of a body wherein the contrast agent is susceptible to destruction by a destructive ultrasound signal, said method comprising the steps of:

(a) determining a first signal level from a first ultrasound echo produced while contrast agent is present in said region;

(b) determining a second signal level of a second ultrasound echo produced after destruction of the contrast agent in said region by the destructive ultrasound signal; and

(c) determining a ratio of the first signal level and the second signal level.

2. The method of claim 1, wherein step (a) and step (b) are executed in consecutive ultrasound imaging frames.

3. The method of claim 1, further comprising the step of:

(d) determining whether blood is perfusing into said region based on the ratio.

4. The method of claim 1, wherein step (c) includes the step of determining a difference between a logarithm of the first signal level and a logarithm of the second signal level.

5. The method of claim 1, wherein the first signal is an average signal level from a plurality of ultrasound echoes produced before, or at a time of, destruction of the contrast agent.

6. The method of claim 1, wherein the second signal level is an average signal level from a plurality of ultrasound echoes produced after destruction of said contrast agent.

7. A method for detecting a relative level of a contrast agent in a region of a body, said contrast agent being susceptible to destruction by a destructive ultrasound signal, said method comprising the steps of:

(a) determining an average signal level from a plurality of ultrasound echoes that are produced in a plurality of spatial subsets of said region;

(b) determining a signal level from an ultrasound echo that is produced in at least one spatial subset of said region; and

(c) determining an arithmetic relationship between said average signal level and said signal level, wherein said arithmetic relationship indicates a relative level of said contrast agent in said at least one spatial subset as compared to said plurality of spatial subsets.

8. The method of claim 7, wherein said arithmetic relationship is a difference between said average signal level and said signal level.

9. The method of claim 7, wherein said arithmetic relationship is a ratio of said average signal level and said signal level.

10. The method of claim 9, wherein step (c) includes the step of determining a difference between a logarithm of said average signal level and a logarithm of said signal level.

11. The method of claim 7, wherein said plurality of spatial subsets defines a sub-region into which blood perfuses, and said method further comprises the step of:

(d) determining whether blood is flowing into said at least one spatial subset based on said relative level of said contrast agent, wherein a rate of blood flow is substantially greater than a rate of blood perfusion.

12. A system for detecting a relative level of a contrast agent in a region of a body, said system comprising:

(a) means for determining a first signal level from a first ultrasound echo produced in the region while the contrast agent is present in the region;

(b) means for determining a second signal level of a second ultrasound echo produced in the region after destruction of the contrast agent; and

(c) means to determine a ratio of the first signal level to the second signal level.

13. The system of claim 12, wherein means (a) and means (b) execute their respective actions in consecutive ultrasound imaging frames.

14. The system of claim 12, further comprising:

(d) means for determining whether blood is perfusing into said region based on the ratio.

15. The system of claim 12, wherein means (c) includes means for determining a difference between a logarithm of the first signal level and a logarithm of the second signal level.

16. The system of claim 12, wherein the first signal level is an average signal level from a plurality of ultrasound echoes produced before, or at a time of, destruction of the contrast agent.

17. The system of claim 12, wherein the second signal level is an average signal level from a plurality of ultrasound echoes produced after destruction of the contrast agent.

18. A system for detecting a relative level of a contrast agent in a region of a body, said contrast agent being susceptible to destruction by a destructive ultrasound pulse, said system comprising:

(a) means for determining an average signal level from a plurality of ultrasound echoes that are produced in a plurality of spatial subsets of said region;

(b) means for determining a signal level from an ultrasound echo that is produced in at least one spatial subset of said region; and

(c) means for determining an arithmetic relationship between said average signal level and said signal level, wherein said arithmetic relationship indicates a relative level of said contrast agent in said at least one spatial subset as compared to said plurality of spatial subsets.

19. The system of claim 18, wherein said arithmetic relationship is a difference between said average signal level and said signal level.

20. The system of claim 18, wherein said arithmetic relationship is a ratio of said average signal level and said signal level.

21. The system of claim 20, wherein means (c) includes means for determining a difference between a logarithm of said average signal level and a logarithm of said signal level.

22. The system of claim 18, wherein said plurality of spatial subsets defines a sub-region into which blood perfuses, and said system further comprises:

(d) means for determining whether blood is flowing into said at least one spatial subset based on said relative level of said contrast agent, wherein a rate of blood flow is substantially greater than a rate of blood perfusion.

23. A computer readable storage media storing software for detecting a relative level of a contrast agent in a region of a body, the software causing a processor to perform the following actions:

(a) determining a first signal level from a first ultrasound echo produced from the region while contrast agent is present in said region;

(b) determining a second signal level of a second ultrasound echo produced from the region after destruction of the contrast agent; and

(c) determining a ratio of the first signal level and the second signal level.

24. The storage media of claim 23, wherein action (a) and action (b) execute their respective actions in consecutive ultrasound imaging frames.

25. The storage media of claim 23, further comprising software to perform the following actions:

(d) determining whether blood is perfusing into said region based on the relative level of said contrast agent.

26. The storage media of claim 23, wherein action (c) determines a difference between a logarithm of the first signal level and the second signal level.

27. The storage media of claim 23, wherein the first signal level is an average signal level from a plurality of ultrasound echoes produced before, or at a time of, destruction of the contrast agent.

28. The storage media of claim 23, wherein the second signal level is an average signal level from a plurality of ultrasound echoes produced after destruction of the contrast agent.

29. A computer readable storage media including software for detecting a relative level of a contrast agent in a region of a body, the software causing a processor to perform the following actions:

(a) determining an average signal level from a plurality of ultrasound echoes that are produced in a plurality of spatial subsets of said region;

(b) determining a signal level from an ultrasound echo that is produced in at least one spatial subset of said region; and

(c) determining an arithmetic relationship between said average signal level and said signal level, wherein said arithmetic relationship indicates a relative level of said contrast agent in said at least one spatial subset as compared to said plurality of spatial subsets.

30. The storage media of claim 29, wherein said arithmetic relationship is a difference between said average signal level and said signal level.

31. The storage media of claim 29, wherein said arithmetic relationship is a ratio of said average signal level and said signal level.

32. The storage media of claim 31, wherein action (c) determines a difference between a logarithm of said average signal level and a logarithm of said signal level.

33. The storage media of claim 29, wherein said plurality of spatial subsets defines a sub-region into which blood perfuses, and said storage media further comprises software for performing the following actions:

(d) determining whether blood is flowing into said at least one spatial subset based on said relative level of said contrast agent, wherein a rate of blood flow is substantially greater than a rate of blood perfusion.

34. A method for determining a relative level of a contrast agent in a region of a body, said contrast agent being susceptible to destruction by a destructive ultrasound signal, said method comprising the steps of:

measuring signal levels from a plurality of ultrasound echoes that arc produced in said region; and

determining a ratio of a signal level from a first measured ultrasound echo produced while said contrast agent is present in said region, and a signal level from a second measured ultrasound echo produced after a destruction of said contrast agent,

wherein said ratio indicates a relative level of said contrast agent after said destruction as compared to when said contrast agent was present.

35. A computer readable storage media storing software for detecting a relative level of a contrast agent in a region of a body, the software causing a processor to perform the following actions:

measuring signal levels from a plurality of ultrasound echoes that are produced in said region;

determining a ratio of a signal level from a first of said plurality of ultrasound echoes that is produced while said contrast agent is present in said region, and a signal level from a second of said plurality of ultrasound echoes produced after destruction of said contrast agent,

wherein said ratio indicates a relative level of said contrast agent after said destruction as compared to when said contrast agent was present.

36. A method for determining a relative level of a contrast agent in a region of a body, said contrast agent being susceptible to destruction by a destructive ultrasound signal, said method comprising the steps of:

measuring signal levels from a plurality of ultrasound echoes that are produced in said region; and

determining an arithmetic relationship between an average signal level from the plurality of ultrasound echoes that are produced in a plurality of spatial subsets of said region, and a signal level from an ultrasound echo that is produced in at least one spatial subset of said region,

wherein said arithmetic relationship indicates a relative level of said contrast agent in said at least one spatial subset as compared to said plurality of spatial subsets.

37. A computer readable storage media storing software for detecting a relative level of a contrast agent in a region of a body, the software causing a processor to perform the following actions:

measuring signals level from a plurality of ultrasound echoes that are produced in said region; and

determining an arithmetic relationship between an average signal level from the plurality of ultrasound echoes that are produced in a plurality of spatial subsets of said region, and a signal level from an ultrasound echo that is produced in at least one spatial subset of said region,

wherein said arithmetic relationship indicates a relative level of said contrast agent in said at least one spatial subset as compared to said plurality of spatial subsets.