DEVICES AND METHODS FOR TRACKING BLOOD FLOW AND DETERMINING PARAMETERS OF BLOOD FLOW

• US 20080269609A1
• Filed: 07/10/2008
• Published: 10/30/2008
• Est. Priority Date: 05/28/1999
• Status: Abandoned Application

• Current Assignee: PhysioSonics, Inc.
• Original Assignee: PhysioSonics, Inc.
• Inventors: Attia, Elsayed H., Abend, Kenneth
• Application Number:
  US12/171,008
• Publication Number:
  US 20080269609A1
• Time in Patent Office: Days
• US Class Current: 600/440
• 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 8/13 Tomography A61B8/10, A61B8/12 take precedence; tomography for radiation diagnosis A61B6/02
• CPC Class Codes: A61B 8/463 characterised by displaying multiple images or images and diagnostic data on one display composite display in devices for short-range imaging with acoustic waves G01S7/52074
• CPC Class Codes: A61B 8/483 involving the acquisition of a 3D volume of data
• CPC Class Codes: G01S 15/52 Discriminating between fixed and moving objects or between objects moving at different speeds
• CPC Class Codes: G01S 15/8927 using simultaneously or sequentially two or more subarrays or subapertures
• CPC Class Codes: G01S 15/8979 Combined Doppler and pulse-echo imaging systems
• CPC Class Codes: G01S 15/899 Combination of imaging systems with ancillary equipment
• 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
• CPC Class Codes: G01S 7/52095 using multiline receive beamforming

Abstract

Provided herein is a method for use in medical applications that permits (1) affordable three-dimensional imaging of blood flow using a low-profile easily-attached transducer pad, (2) real-time blood-flow vector velocity, and (3) 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.

A thinned array (greater than half-wavelength element spacing of the transducer array) is used to make a device of the present invention inexpensive and allow the pad to have a low profile (fewer connecting cables for a given spatial resolution). The full aperture is used for transmit and receive so that there is no loss of sensitivity (signal-to-noise ratio) or dynamic range. Utilizing more elements (extending the physical array) without increasing the number of active elements increases the angular field of view. A further increase is obtained by utilizing a convex non-planar surface.

Claims

1. A method for long term Doppler ultrasound monitoring using an array of ultrasound transducer elements, comprising:

collecting and Doppler processing ultrasound blood velocity data in a three dimensional region;

locking onto and tracking the point(s) in three-dimensional space that produce the locally maximum blood velocity signals.

2. A method of claim 1, additionally comprising measuring radial velocity at the point(s).

3. A method of claim 1, additionally comprising forming a three-dimensional map of at least one blood vessel based on integrating coordinates of points acquired by the tracking process.

4. A method of claim 1, wherein the ultrasound blood velocity data is radial Doppler data, and additionally comprising calculating vector velocity from the Doppler ultrasound blood velocity data.

5. A method of claim 1, additionally comprising providing a display that allows selection of multiple points of interest for expanded data collection.

6. A method of claim 1, additionally comprising forming a broad ultrasound transmit beam encompassing a plurality of narrow receive beams and initially acquiring the blood velocity data by insonating a large region.

7. A method of claim 1, additionally comprising applying post Doppler sub-resolution processing to locate the point(s) being tracked to an accuracy that is finer than the resolution.

8. A method of claim 1, additionally comprising tracking and maintaining focus on multiple blood vessels.

9. A method of claim 1, additionally comprising performing color velocity imaging.

10. A method of claim 1, additionally comprising forming and displaying a choice of projection, slice or perspective views.

11. A method of claim 1, additionally comprising displaying at least one of instantaneous blood flow velocity and average blood flow velocity and estimated average blood flow volume.

12. A method of claim 1, additionally comprising maintaining a multi-day history and displaying average blood flow velocity versus time for each monitored vessel over a time period.

13. A method of claim 1, additionally comprising sounding an alarm when at least one of a maximum blood flow velocity, a minimum blood flow velocity, and an emboli count is high.

14. A method of claim 1, additionally comprising electronically rotating the array or portions of the array using digital processing techniques.

15. A transcranial Doppler device for long term Doppler ultrasound monitoring comprising an array of ultrasound transducer elements and processing electronics that produce and digitally analyze data composed of ultrasound signal return amplitude as a function of depth, azimuth, elevation, radial blood velocity and time and that automatically locates and locks onto the point(s) with the maximum volume of blood having a significant radial velocity.

16. An ultrasound device comprising an array of ultrasound transducer elements and additionally comprising processing electronics programmed to operate the array differently in transmit and receive modes, to form a transmit beam encompassing a plurality of receive beams for initially acquiring a signal by insonating a target region comprising multiple receive beam positions simultaneously, to receive and Doppler process data from the multiple receive beam positions of the array, and to lock onto and track the point(s) in three-dimensional space that produce the locally maximum blood velocity signals.

17. A device of claim 16, wherein the processing electronics are programmed to steer the receive beams using a phase steering or time-delay steering technique.

18. A device of claim 16, wherein the processing electronics are additionally programmed to correct for motions in the target region by periodically forming multiple receive beams and re-acquiring a peak signal.

19. A device of claim 16, wherein the array of ultrasound transducer elements is provided on a low-profile easily-attached transducer pad.

20. A device of claim 16, wherein the processing electronics are additionally programmed to determine spatial coordinates of received data.

21. A device of claim 20, additionally comprising a display device, and wherein the processing electronics are additionally programmed to form and display a 3D map based on the spatial coordinates of received data.