Device and method for mapping and tracking blood flow and determining parameters of blood flow

• US 7,534,209 B2
• Filed: 12/20/2002
• Issued: 05/19/2009
• Est. Priority Date: 05/26/2000
• Status: Expired due to Fees

• Current Assignee: PhysioSonics, Inc.
• Original Assignee: PhysioSonics, Inc.
• Inventors: Attia, Elsayed Hesham, Abend, Kenneth
• Primary Examiner(s): Casler; Brian L.
• Assistant Examiner(s): Shahrestani; Nasir
• Application Number:
  US10/327,265
• Publication Number:
  US 20040019278A1
• Time in Patent Office: 2,342 Days
• Field of Search: 600407-480, 367/7, 367/11, 367/130, 367/138, 736/25, 736/26, 128/916
• US Class Current: 600/454
• CPC Class Codes: G01S 15/8979 Combined Doppler and pulse-echo imaging systems
• CPC Class Codes: G01S 15/8993 Three dimensional imaging systems
• CPC Class Codes: G01S 7/52026 Extracting wanted echo signals Doppler systems G01S15/50; Doppler short range imaging systems G01S15/8979
• CPC Class Codes: G01S 7/52034 Data rate converters
• CPC Class Codes: G01S 7/5206 Two-dimensional coordinated display of distance and direction; B-scan display
• CPC Class Codes: G01S 7/52061 Plan position indication (PPI display); C-scan display
• CPC Class Codes: G01S 7/52065 Compound scan display, e.g. panoramic imaging
• CPC Class Codes: G01S 7/52071 Multicolour displays; using colour coding; Optimising colour or information content in displays, e.g. parametric imaging
• CPC Class Codes: G01S 7/52073 Production of cursor lines, markers or indicia by electronic means
• CPC Class Codes: G01S 7/52074 Composite displays, e.g. split-screen displays; Combination of multiple images or of images and alphanumeric tabular information
• CPC Class Codes: G01S 7/52079 Constructional features constructional features of transducers B06B; mounting transducers G10K11/00; constructional features of ultrasonic medical diagnostic devices A61B8/44

Abstract

Provided herein is a method for use in medical applications that permits affordable three-dimensional imaging of blood flow using a low-profile easily-attached transducer pad, real-time blood-flow vector velocity, and long-term unattended Doppler-ultrasound monitoring in spite of motion of the patient or pad. The pad and associated processor collects and Doppler processes ultrasound blood velocity data in a three dimensional region through the use of a planar phased array of piezoelectric elements. The invention locks onto and tracks the points in three-dimensional space that produce the locally maximum blood velocity signals. The integrated coordinates of points acquired by the accurate tracking process is used to form a three-dimensional map of blood vessels and provide a display that can be used to select multiple points of interest for expanded data collection and for long term continuous and unattended blood flow monitoring. The three dimensional map allows for the calculation of vector velocity from measured radial Doppler.

Claims

1. A method for determining a parameter of blood flow in a blood vessel of interest, comprising the steps of:

a) providing an array of sonic transducer elements, wherein the element spacing in the array is greater than, equal to or less than a half wavelength of the sonic energy produced by the elements, wherein at least one element transmits sonic energy, and a portion of the elements receive sonic energy;

b) transmitting sonic energy produced by the at least one element of the array into a volume of the subject'"'"'s body having the blood vessel of interest,

c) receiving echoes of the sonic energy from the volume of the subject'"'"'s body having the blood vessel of interest;

d) reporting the echoes to a processor electrically connected to the elements of the array, wherein the processor is programmed to

i) Doppler process the echoes to determine radial velocity of the blood flowing in the blood vessel of interest;

ii) determine a sum beam, an azimuth difference beam and an elevation difference beam from the echoes received from the blood vessel of interest;

iii) modulate the directions of the transmitted and received sonic energy based upon the sum, azimuth difference and elevation difference beams in order to lock on to the highest Doppler energy calculated from echoes from the flow of blood in the blood vessel of interest;

iv) calculate the three dimensional position of the highest Doppler energy from the blood flow in the vessel of interest; and

v) calculate the parameter of blood flow in the blood vessel at the three dimensional position calculated in step (iv).

34. A method of any one of claims 1, 3 and 27, additionally comprising determining at least one additional beam having an angle between the azimuth difference beam and the elevation difference beam.

36. A method of any one of claims 1, or 27 and 28, additionally comprising:

periodically repeating the transmitting, receiving, identifying and locking on to steps.

43. A method of any one of claims 1, 2 and 27, additionally comprising Doppler processing the ultrasound energy echoes and determining a radial velocity of blood flowing in the blood vessel of interest at the selected point or points.

44. A method of any one of claims 1, 2 and 27, additionally comprising generating a three-dimensional map of the blood vessel of interest.

2. A method for tracking blood flow in a blood vessel of interest, comprising the step of:

providing an array of ultrasound transducer elements, wherein the element spacing in the array is greater than, equal to or less than a half wavelength of the ultrasound energy produced by the elements, wherein at least one element transmits ultrasound energy and a portion of the elements receive ultrasound energy;

transmitting ultrasound energy produced by the at least one element of the array into a volume of subject'"'"'s body having the blood vessel of interest;

receiving echoes of the ultrasound energy from the volume of the subject'"'"'s body having the blood vessel of interest at the portion of the elements;

modulating a direction of the transmitted and received ultrasound energy based on the echoes received;

automatically identifying and locking on to a selected point or points in the volume based on information obtained from the echoes of ultrasound energy; and

periodically repeating the transmitting, receiving, identifying and locking on to steps.

3. A method of claim 2, additionally comprising determining a sum beam, an azimuth difference beam and an elevation difference beam based on the ultrasound energy echoes.

37. A method of claims 2 or 27 additionally comprising identifying and locking on to a point or points in the volume having the highest Doppler energy calculated from the ultrasound energy echoes.

38. A method of claims 2 or 27, additionally comprising identifying and locking on to a point or points in the volume having a peak response within a range of Doppler frequencies.

39. A method of claims 2 or 27, additionally comprising periodically calculating a parameter of blood flow at a point or points in the volume having the blood vessel of interest.

40. A method of claim 39, wherein the parameter of blood flow calculated is at least one of vector velocity, blood flow volume and Doppler spectral distribution.

41. A method of claim 39, additionally comprising periodically displaying a parameter of blood flow at a point or points in the volume having the blood vessel of interest on a display monitor.

42. A method of claim 39, additionally comprising calculating a three dimensional position of a point or points in the volume having the blood vessel of interest at which the parameter of blood flow is calculated.

4. A method for monitoring a parameter of blood flow in a blood vessel of interest, comprising:

attaching a low-profile two-dimensional ultrasound probe to a portion of the body near a general volume location of the blood vessel of interest;

insonating a three dimensional volume including the blood vessel of interest with ultrasound energy;

collecting Doppler ultrasound data from the three dimensional volume including the blood vessel of interest;

identifying a point in the three-dimensional volume at which the parameter is desired to be measured based on the Doppler data;

Doppler processing the ultrasound data and determining a radial velocity of blood flowing at the point in three-dimensional space at which the parameter is desired to be measured;

continuing to collect Doppler data from the point in the three dimensional volume; and

automatically tracking and maintaining focus on the point in the three-dimensional volume at which the parameter is desired to be measured based on the collected Doppler data.

5. A method of claim 4, additionally comprising modulating a direction of the insonating ultrasound energy based on the collected Doppler data.

6. A method of claim 4, additionally comprising periodically repeating the insonating, collecting, identifying, continuing and tracking steps and additionally modulating a direction of the insonating ultrasound energy based on the collected Doppler data.

7. A method of claim 4, additionally comprising identifying and tracking a point in three-dimensional space having the highest Doppler energy.

8. A method of claim 4, additionally comprising periodically calculating a parameter of blood flow at the point in three-dimensional space.

9. A method of claim 8, wherein the parameter of blood flow calculated is at least one of vector velocity, blood flow volume and Doppler spectral distribution.

10. A method of claim 8, additionally comprising periodically displaying a parameter of blood flow at the point in three-dimensional space.

11. A method of claim 8, additionally comprising calculating a three dimensional position of blood flow at the point in three-dimensional space.

12. A method of claim 4, additionally comprising generating a three dimensional map of the blood vessel of interest.

13. A method of claim 4, additionally comprising identifying of multiple points in three-dimensional space at which the parameter is desired to be measured for expanded data collection.

14. A method of claim 4, wherein the blood vessel of interest is the middle cerebral artery (MCA).

15. A device for monitoring blood flow in a blood vessel of interest, comprising:

a low profile two-dimensional array of ultrasound transducer elements, wherein the element spacing in the array is greater than, equal to or less than a half wavelength of the ultrasound energy produced by the elements, wherein at least one element transmits ultrasound energy and a portion of the elements receive ultrasound energy echoes; and

a processor electrically connected to the array programmed to Doppler process the ultrasound energy echoes, automatically identify and lock on to a selected point or points based on information obtained from ultrasound energy echoes, and determine a radial velocity of blood flowing at the selected point or points.

16. A device of claim 15, additionally comprising a display monitor electrically connected to the processor.

17. A device of claim 15, wherein the processor is additionally programmed to calculate a blood flow parameter selected from the group consisting of:

blood flow volume, vector velocity and Doppler spectral distribution.

18. A device of claim 17, wherein the processor is additionally programmed to calculate an instantaneous value of the blood flow parameter.

19. A device of claim 17, wherein the processor is additionally programmed to calculate an averaged value of the blood flow parameter detennined over a heart cycle.

20. A device of claim 15, wherein the processor is additionally programmed to modulate the direction of transmitted and received ultrasound energy based on information obtained from ultrasound energy echoes.

21. A device of claim 15, wherein the ultrasound transducer elements are electronically steered to suppress grating lobes.

22. A device of claim 15, wherein the ultrasound transducer elements are positioned and sized to be flush against each other.

23. A device of claim 15, wherein the array of ultrasound transducer elements is steerable by time delay steering.

24. A device of claim 15, wherein the distance between elements of the array is greater than 1/2 the wavelength of the ultrasound energy.

25. A device of claim 15, wherein the distance between elements of the array is less than 1/2 the wavelength of the ultrasound energy.

26. A device of claim 15, wherein the distance between elements of the array is equal to 1/2 the wavelength of the ultrasound energy.

30. A device of claim 15 or 29, wherein the array is

a two dimensional phased array of ultrasound transducer elements arranged on a planar, cylindrical or spherical surface.

31. A device of claim 15 or 29, wherein the array of ultrasound transducer elements has an approximately circular aperture.

32. A device of claim 15 or 29, wherein the array of ultrasound transducer elements has an approximately elliptical aperture.

47. A device of any one of claims, 30, 31, 32 and 33 wherein the array of ultrasound transducer elements is electronically steerable.

48. A device of any one of claims 15, 30, 31, 32 and 33, wherein the array of ultrasound transducer elements is steerable by digital beamforming techniques.

27. A method for tracking blood flow in a blood vessel of interest, comprising the steps of:

providing an array of ultrasound transducer elements, wherein the element spacing in the array is greater than, equal to or less than a half wavelength of the ultrasound energy produced by the elements, wherein at least one element transmits ultrasound energy and a portion of the elements receive ultrasound energy;

transmitting ultrasound energy produced by the at least one element of the array into a volume of a subject'"'"'s body having the blood vessel of interest;

receiving echoes of the ultrasound energy from the volume of the subject'"'"'s body having the blood vessel of interest at the portion of the elements;

determining a sum beam, an azimuth difference beam and an elevation difference beam based on the ultrasound energy echoes; and

automatically identifying and locking on to a selected point or points in the volume based on information obtained from the echoes of ultrasound energy.

35. A method of claim 3 or 27, additionally comprising modulating a direction of the transmitted and received ultrasound energy based upon the sum, azimuth difference and elevation difference beams.

28. A method for tracking blood flow in a blood vessel of interest, comprising the steps of:

providing an array of ultrasound transducer elements, wherein the element spacing in the array is greater than, equal to or less than a half wavelength of the ultrasound energy produced by the elements, wherein at least one element transmits ultrasound energy and a portion of the elements receive ultrasound energy;

transmitting ultrasound energy produced by the at least one element of the array into a volume of a subject'"'"'s body having the blood vessel of interest;

receiving echoes of the ultrasound energy from the volume of the subject'"'"'s body having the blood vessel of interest at the portion of the elements;

Doppler processing the ultrasound energy echoes and determining a radial velocity of blood flowing in the blood vessel of interest at the selected point or points; and

automatically identifying and locking on to a selected point or points in the volume based on information obtained from the echoes of ultrasound energy.

29. A device for monitoring blood flow in a blood vessel of interest, comprising:

an array of ultrasound transducer elements, wherein the element spacing in the array is greater than, equal to or less than a half wavelength of the ultrasound energy produced by the elements, wherein at least one element transmits ultrasound energy and a portion of the elements receive ultrasound energy echoes; and

a processor electrically counected to the array programmed to electronically steer the ultrasound transducer elements to suppress grating lobes, Doppler process the ultrasound energy echoes, determine a sum beam, an azimuth difference beam and an elevation difference beam. modulate the direction of the transmitted and received ultrasound energy based on the ultrasound energy echoes, and automatically identify and lock on to a selected point or points based on information obtained from ultrasound energy echoes.

46. A device of any one of claims 29, 30, 31, 32 and 33 wherein the array of ultrasound transducer elements is a low profile two-dimensional array.

49. A device of any one of claims 29, 30, 31 and 32, wherein the array of ultrasound transducer elements is provided on a low-profile, easily-attached transducer pad.

33. A device for monitoring blood flow in a blood vessel of interest, comprising:

a

n array of ultrasound transducer elements forming an octagon, wherein the element spacing in the array is greater than, equal to or less than a half wavelength of the ultrasound energy produced by the elements, wherein at least one element transmits ultrasound energy and a portion of the elements receive ultrasound energy echoes; and

a processor electrically connected to the array programmed to Doppler process the ultrasound energy echoes and automatically identify and lock on to a selected point or points based on information obtained from ultrasound energy echoes.

45. A method of any one of claims l, 2 and 27, additionally comprising identifying multiple points of interest in the volume for expanded data collection.