REAL-TIME PHOTOACOUSTIC AND ULTRASOUND IMAGING SYSTEM AND METHOD

• US 20170079622A1
• Filed: 05/11/2015
• Published: 03/23/2017
• Est. Priority Date: 05/12/2014
• Status: Active Grant

• Current Assignee: University of Washington, Washington University In St Louis
• Original Assignee: University of Washington
• Inventors: O'Donnell, Matthew, Nguyen, Thu-Mai, Wei, Chen-Wei, Xia, Jinjun
• Granted Patent: US 10,888,304 B2
• Time in Patent Office: Days
• CPC Class Codes: A61B 5/0035 adapted for acquisition of images from more than one imaging mode, e.g. combining MRI and optical tomography
• CPC Class Codes: A61B 5/0095 by applying light and detecting acoustic waves, i.e. photoacoustic measurements
• CPC Class Codes: A61B 8/0841 for locating instruments
• CPC Class Codes: A61B 8/14 Echo-tomography
• CPC Class Codes: A61B 8/4416 related to combined acquisition of different diagnostic modalities, e.g. combination of ultrasound and X-ray acquisitions
• CPC Class Codes: A61B 8/4483 characterised by features of the ultrasound transducer
• 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 8/5261 combining images from different diagnostic modalities, e.g. ultrasound and X-ray

Abstract

Methods and system for producing combined photoacoustic/ultrasonic image frames use a low-power narrow beam laser to direct sequential pulses along a path overlying an internal region of interest. Photoacoustic responses are received and used to generate sub-frames. Between each of the laser pulses a plurality of ultrasound pulse-echo beams are sequentially emitted towards the region of interest, and the reflections are received and used to generate ultrasound sub-frames. The photoacoustic sub-frames are combined to produce a photoacoustic frame, and the ultrasound sub-frames are combined to produce an ultrasound frame. The photoacoustic and ultrasound frames are combined to produce an image frame. The method and system are suitable for producing real-time, high-contrast video.

Claims

1. A method for generating a combined photoacoustic and ultrasound image frame of an internal region of a body having an external surface, the method comprising:

irradiating a first location on the external surface with a first laser pulse such that the first laser pulse irradiates the internal region of the body;

receiving a first photoacoustic response to the first laser pulse, and using the received first photoacoustic response to generate a first photoacoustic sub-frame of the internal region of the body;

sequentially transmitting a first plurality of ultrasound pulse-echo beams towards a first section of the internal region of the body;

receiving a first set of ultrasound reflections of the first plurality of ultrasound pulse-echo beams and using the received first set of ultrasound reflections to generate a first set of ultrasound sub-frames of the internal region of the body;

irradiating a second location on the external surface with a second laser pulse such that the second laser pulse irradiates the internal region of the body, wherein the second location is different from the first location;

receiving a second photoacoustic response to the second laser pulse, and using the received second photoacoustic response to generate a second photoacoustic sub-frame of the internal region of the body;

sequentially transmitting a second plurality of ultrasound pulse-echo beams toward a second section of the internal region of the body, wherein the second section is different from the first section;

receiving a second set of ultrasound reflections of the second plurality of ultrasound pulse-echo beams, and using the received second set of ultrasound reflections to generate a second set of ultrasound sub-frames of the internal region of the body;

combining the first and second photoacoustic sub-frames to generate a photoacoustic frame of the internal region of the body, and combining the first and second sets of ultrasound sub-frames to generate an ultrasound frame of the internal region of the body; and

combining the photoacoustic frame and the ultrasound frame to generate an image frame of the internal region of the body.

2. The method of claim 1, wherein the first laser pulse and the second laser pulse have energies of less than 10 millijoules.

3. The method of claim 1, wherein the first laser pulse and the second laser pulse have energies of less than 2 millijoules.

4. The method of claim 1, wherein the first laser pulse and the second laser pulse each have a diameter that is less than 3 mm.

5. The method of claim 1, wherein the first laser pulse has a wavelength between 400 nm and 1500 nm, and further wherein the first laser pulse has a fluence that is less than a wavelength-dependent maximum fluence that would damage tissue.

6. The method of claim 1, wherein the first laser pulse and the second laser pulse have a pulse fluence less than 100 mJ/cm².

7. The method of claim 1, wherein the first plurality of ultrasound pulse-echo beams comprise at least six pulse-echo beams.

8. The method of claim 1, wherein the first and second laser pulses are produced by a laser diode-pumped Q-switched laser.

9. The method of claim 1, wherein the first plurality of ultrasound pulse-echo beams is generated with an ultrasound linear array.

10. The method of claim 9, wherein the ultrasound linear array receives the first and second photoacoustic responses and the first and second sets of ultrasound reflections.

11. The method of claim 9, wherein the ultrasound linear array is disposed in a probe, and further wherein the first and second laser pulses are emitted from the probe.

12. The method of claim 11, wherein the probe comprises a distal face configured to be positioned against the body, and wherein a plurality of optical fibers are configured to transmit the first and second laser pulses from a laser to the distal face of the probe.

13. The method of claim 12, wherein a remote switching unit distributes the first and second laser pulses to selected ones of the plurality of optical fibers.

14. The method of claim 12, wherein the plurality of optical fibers extend along both sides of the ultrasound linear array.

15. The method of claim 1, further comprising (i) irradiating additional locations on the external surface with additional laser pulses, (ii) receiving corresponding photoacoustic responses and generating additional photoacoustic sub-frames;

(iii) sequentially transmitting additional pluralities of ultrasound pulse-echo beams towards the additional sections of the internal region of the body, (iv) receiving corresponding ultrasound reflections and generating additional sets of ultrasound sub-frames of the internal region of the body, (v) including the additional photoacoustic sub-frames with the first and second photoacoustic sub-frames to generate the photoacoustic frame, and including the additional ultrasound sub-frames with the first and second ultrasound sub-frames to generate the ultrasound image frame.

16. The method of claim 15, wherein the number of additional locations comprise at least twenty-two additional locations.

17. A method for generating a real-time video of the internal region of the body, wherein the method of claim 1 is used to generate a sequence of image frames of the internal region of the body, and displaying the sequence of images as frames of the real-time video.

18. A method for generating a combined photoacoustic and ultrasound image of an internal region of a body having an external surface, the method comprising:

irradiating the external surface of the body with sequential narrow-beam, lower power laser pulses that irradiate the internal region of the body, wherein the sequential laser pulses are directed to a plurality of different locations along a path on the external surface, and receiving photoacoustic signals from the body corresponding to the sequential laser pulses;

between each of the sequential laser pulses, sequentially transmitting a plurality of ultrasound pulse-echo beams to the internal region of the body, and receiving ultrasound reflections of the plurality of ultrasound pulse-echo beams;

generating a first set of sub-frames from the received photoacoustic signals;

generating a second set of sub-frames from the received ultrasound reflections; and

combining the first set of sub-frames with the second set of sub-frames to generate a combined photoacoustic and ultrasound image frame of the internal region of the body.

19. A combined photoacoustic and ultrasound imaging system for imaging an interior region of a target, the system comprising:

an ultrasound linear array configured to generate ultrasound pulses, to receive and process ultrasound reflection data, and to receive and process photoacoustic signals;

a laser configured to generate narrow-beam laser pulses having a pulse energy of less than 5 mJ;

a laser pulse distributor configured to receive laser pulses from the laser and to direct the pulses to a plurality of locations on a target;

a computer system configured to control the ultrasound linear array, the laser, and the laser pulse distributor, to receive processed ultrasound reflection data and photoacoustic signals from the ultrasound linear array, and to generate combined photoacoustic and ultrasound images from the received data and signals.