Real-time photoacoustic and ultrasound imaging system and method

Patent metadata

Field	Value
Publication number	US-10888304-B2
Application number	US-201515308828-A
Country	US
Kind code	B2
Filing date	May 11, 2015
Priority date	May 12, 2014
Publication date	Jan 12, 2021
Grant date	Jan 12, 2021

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.

First claim

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

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:
performing in sequence, to generate an image frame of the internal region of the body:
irradiating a first location on the external surface with a first laser pulse such that the first laser pulse irradiates a first section of 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 to scan the 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 a second section of the internal region of the body, wherein the second location on the external surface is different from the first location on the external surface;
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 to scan the second section of the internal region of the body, wherein the second section of the internal region of the body is different from the first section of the internal region of the body;
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 the 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/cm 2 .

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 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,
wherein the system is configured to generate a combined photoacoustic and ultrasound image frame of the interior region of the target using the method of claim 1 .

19. The imaging system of claim 18 , wherein the laser pulse distributor comprises a switching unit in which laser pulses from the laser are directed sequentially into a plurality of fibers that extend into a probe containing the ultrasound linear array.

Assignees

• Univ Washington

Inventors

• O'Donnell Matthew
• Nguyen Thu-Mai
• Wei Chen-Wei
• Xia Jinjun
• Pelivanov Ivan
• Yoon Soon Joon

Classifications

• A61B8/463

  characterised by displaying multiple images or images and diagnostic data on one display · CPC title

• A61B8/0841

  for locating instruments · CPC title

• A61B8/4416

  related to combined acquisition of different diagnostic modalities, e.g. combination of ultrasound and X-ray acquisitions · CPC title

• A61B8/5261 Primary

  combining images from different diagnostic modalities, e.g. ultrasound and X-ray · CPC title

• A61B5/0035

  adapted for acquisition of images from more than one imaging mode, e.g. combining MRI and optical tomography · CPC title