System and method for synchronized persistence with contrast agent imaging

• US 6,612,989 B1
• Filed: 06/18/2002
• Issued: 09/02/2003
• Est. Priority Date: 06/18/2002
• Status: Expired due to Term

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Brock-Fisher, George
• Primary Examiner(s): Jaworski, Francis J.
• Assistant Examiner(s): PATEL, MAULIN M
• Application Number:
  US10/174,282
• Time in Patent Office: 441 Days
• Field of Search: 600/437, 600/441, 600/442, 600/443, 600/447, 600/449, 600/454, 600/455, 600/456
• US Class Current: 600/447
• CPC Class Codes: A61B 5/352 Detecting R peaks, e.g. for synchronising diagnostic apparatus; Estimating R-R interval
• 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
• CPC Class Codes: A61B 8/543 involving acquisition triggered by a physiological signal
• CPC Class Codes: G01S 15/8977 using special techniques for image reconstruction, e.g. FFT, geometrical transformations, spatial deconvolution, time deconvolution
• 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

Abstract

A system and method for synchronized persistence with ultrasonic harmonic imaging of both tissue and tissue perfused with a contrast agent are disclosed. The ultrasonic harmonic imaging system comprises a frame memory, a frame processor, a persistence actuator, and a persistence controller. In a preferred embodiment, the persistence actuator disables persistence filtering in response to contrast agent destructive ultrasonic transmissions. A method for observing an ultrasonic response of a contrast agent may be performed by: introducing a contrast agent into tissue targeted for imaging; insonifying the tissue with a first ultrasound transmit signal suited to observe the contrast agent and the tissue; modifying a transmit signal parameter to destroy a substantial portion of the contrast agent; disabling persistence filtering while the modified transmit signal is actuated; and enabling persistence filtering while observing the re-perfusion of the tissue.

Claims

1. A method for observing an ultrasonic response of a contrast agent comprising:

introducing at least one contrast agent into tissue targeted for imaging;

insonifying tissue with a transducer excited by a first ultrasound-transmit signal suited to peimit real-time observation of contrast agent perfused tissue;

modifying at least one ultrasonic-transmit signal parameter to generate a second ultrasound-transmit signal wherein a substantial portion of the contrast agent present within the insonified tissue is destroyed; and

actuating a persistence filter in response to the second ultrasonic-tranismit signal wherein successive image frames acquired after the second ultrasonic-transmit signal is applied are not compromised by persistence filtered results.

2. The method of claim 1, further comprising:

reapplying the first ultrasound-transmit signal to permit real-time observation of contrast agent re-perfusion through the tissue targeted for imaging; and

actuating the persistence filter in response to the reapplication of the first ultrasound-transmit signal.

3. The method of claim 1, wherein the first ultrasound-transmit signal comprises a mechanical index (MI) selected wherein the at least one contrast agent introduced in the tissue is substantially unaltered over time.

4. The method of claim 1, wherein the first ultra-sound-transmit signal comprises a frequency above approximately 1.5 MHz.

5. The method of claim 1, wherein the second ultrasound-transmit signal comprises a mechanical index (MI) selected wherein the at least one contrast agent introduced in the tissue is substantially destroyed over time.

6. The method of claim 1, wherein the second ultrasound-transmit signal comprises a frequency below approximately 1.5 MHz.

7. The method of claim 1, wherein the step of modifying is performed in response to a trigger signal.

8. The method of claim 1, wherein the step of actuating comprises disabling the persistence filter.

9. The method of claim 1, wherein the step of actuating comprises resetting the persistence filter.

10. The method of claim 2, wherein the step of actuating comprises enabling the persistence filter.

11. The method of claim 7, wherein the trigger signal is generated in response to at least one patient derived parameter.

12. The method of claim 11, wherein the at least one patient derived parameter is an electrocardiogram waveform.

13. In a method for diagnosing blood flow through a vessel of interest wherein at least one contrast agent has been introduced into the blood and wherein at least one set of ultrasonic image frames are analyzed over time to observe the re-perfusion of the at least one contrast agent within the vessel of interest, the improvement comprising:

synchronously actuating a persistence filter in response to an environmental condition that results in a substantial increase in the magnitude of a detected ultrasonic signal reflected from the at least one contrast agent within the blood wherein successive image frames acquired after the environmental condition has been removed are not compromised by the persistence filter.

14. The method of claim 13, further comprising:

estimating the rate of blood flow through the vessel of interest in response to the rate of re-perfusion of the at least one contrast agent through the vessel of interest.

15. The method of claim 13, further comprising:

estimating the blood volume in a vessel of interest in response to a contrast agent maximum intensity and a measure of the distance between the internal surfaces of the vessel as displayed.

16. The method of claim 15, further comprising:

estimating the available oxygen to those portions of tissue supplied by the vessel of interest in response to a patient blood oxygen saturation level.

17. An ultrasonic imaging system for harmonic imaging of at least one contrast agent and tissue in a patient, the system comprising:

means for insonifying a contrast agent perfused tissue of interest with a plurality of ultrasonic pulses wherein the at least one contrast agent can be observed over time;

means for controllably modifying at least one ultrasonic transmit pulse wherein the at least one contrast agent is modified such that the at least one contrast agent can no longer be observed in the tissue of interest; and

means for removing the residual effects of a persistence filter from an ultrasound response processing path in response to the modifying means wherein persistence filtering is not applied during a period substantially co-existing with the application of the modified at least one ultrasonic transmit pulse.

18. The system of claim 17, wherein the means for removing is replaced by means for bypassing a persistence filter from an ultrasound response processing path in response to the modifying means wherein persistence filtering is not applied during a period substantially co-existing with the application of the modified at least one ultrasonic transmit pulse.

19. The system of claim 17, wherein the means for removing comprises replacing data associated with a first image frame with data associated with a successive image frame.

20. The system of claim 17, wherein the means for removing comprises replacing data associated with a first image frame with data associated with an immediately preceding image Frame.

21. The system of claim 17, further comprising:

means for diagnosing at least one blood flow parameter.

22. The system of claim 21, wherein the diagnosing means comprises monitoring the re-perfusion of the at least one contrast agent in the tissue of the patient.

23. An ultrasonic diagnostic imaging system for harmonic imaging of at least one contrast agent and tissue in a patient, the system comprising:

a frame memory which temporarily stores a plurality of image frames;

a frame processor coupled to the frame memory wherein the frame processor is configured to generate an output containing image data on a pixel basis;

a persistence actuator responsive to at least one ultrasound transmit signal; and

a persistence controller configured to receive the frame processor output wherein the persistence controller mathematically combines image data on a pixel basis from successive image frames in response to the persistence actuator, wherein the persistence actuator disables the persistence controller in response to the at least one ultrasound transmit signal when the transmit signal is configured such that it will substantially destroy the at least one contrast agent in the tissue.

24. The system of claim 23, wherein the persistence actuator disables the persistence controller for a predetermined number of image frames.

25. The system of claim 23, wherein the persistence actuator resets the persistence controller for a predetermined number of image frames.