Laser Optoacoustic Ultrasonic Imaging System (LOUIS) and Methods of Use

• US 20130190595A1
• Filed: 01/23/2013
• Published: 07/25/2013
• Est. Priority Date: 01/23/2012
• Status: Active Grant

• Current Assignee: TomoWave Laboratories, Inc.
• Original Assignee: TomoWave Laboratories, Inc.
• Inventors: Oraevsky, Alexander A., Ermilov, Sergey A., Conjusteau, Andre, Anastasio, Mark
• Granted Patent: US 11,160,456 B2
• Time in Patent Office: Days
• US Class Current: 600/407
• CPC Class Codes: A61B 2562/14 Coupling media or elements to improve sensor contact with skin or tissue
• CPC Class Codes: A61B 2562/146 for optical coupling
• CPC Class Codes: A61B 2576/00 Medical imaging apparatus involving image processing or analysis A61B1/00009, A61B6/52 and A61B8/52 take precedence; image processing per se G06T; details of algorithms for analysing medical images G06T7/0012
• 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 5/4312 Breast evaluation or disorder diagnosis A61B5/0091 takes precedence
• CPC Class Codes: A61B 5/708 Breast positioning means
• CPC Class Codes: A61B 8/0825 for diagnosis of the breast, e.g. mammography
• 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 8/483 involving the acquisition of a 3D volume of data
• CPC Class Codes: G16H 30/40 for processing medical images, e.g. editing

Abstract

Provided herein are the systems, methods, components for a three-dimensional tomography system. The system is a dual-modality imaging system incorporates a laser ultrasonic system and a laser optoacoustic system. The dual-modality imaging system has means for generate tomographic images of a volume of interest in a subject body based on speed of sound, ultrasound attenuation and/or ultrasound backscattering and for generating optoacoustic tomographic images of distribution of the optical absorption coefficient in the subject body based on absorbed optical energy density or various quantitative parameters derivable therefrom. Also provided is a method for increasing contrast, resolution and accuracy of quantitative information obtained within a subject utilizing the dual-modality imaging system. The method comprises producing an image of an outline boundary of a volume of interest and generating spatially or temporally coregistered images based on speed of sound and/or ultrasonic attenuation and on absorbed optical energy within the outlined volume.

Claims

1. A laser ultrasonic imaging system, comprising:

a) means for delivering short pulses of optical energy to an array of ultrasonic emitters comprising optically absorbing elements placed in specific locations configured for efficient conversion of the absorbed optical energy into a short pulses of acoustic energy within a wide band of ultrasonic frequencies;

b) means for delivering said short ultrasonic pulses with known amplitude and ultrasonic frequency spectrum through a coupling medium to a volume of interest in a subject at a given time or time zero;

c) means for detecting said ultrasonic pulses in multiple positions at or around said volume of interest and measuring one or more parameters of time of propagation, amplitude and ultrasonic frequency spectrum, after said ultrasonic pulses are transmitted through or reflected from the volume of interest using an array of wide-band ultrasonic transducers that convert ultrasonic pulses into electronic signals;

d) means for analog amplification and digital recording of said electronic signals;

e) means for performing signal processing to remove distortions of electronic signals;

f) means for image reconstruction using mathematical tomography algorithms;

g) means for image processing and display;

h) means for data transmission and system control.

2. The imaging system of claim 1, wherein said system is configured to produce in real time at a video rate two-dimensional images of thin tissue slices based on measured parameters of the speed of sound, ultrasound attenuation or ultrasound backscattering.

3. The imaging system of claim 1, wherein said system is configured to produce three-dimensional images of the volume of interest in a subject body based on measured parameters of the speed of sound, ultrasound attenuation or ultrasound scattering.

4. The imaging system of claim 1, wherein the means for detecting said ultrasonic pulses comprises a hand-held probe configured for acquisition, reconstruction and display of real-time two-dimensional or three-dimensional images.

5. A dual-modality imaging system, comprising:

a) first means comprising the laser ultrasonic system of claim 1 configured to generate tomographic images of a volume of interest in a subject body utilizing parameters comprising one or more of the speed of sound, ultrasound attenuation or ultrasound backscattering; and

b) second means for generating optoacoustic tomographic images of distribution of the optical absorption coefficient in the subject body utilizing parameters of the absorbed optical energy density or various quantitative parameters that can be derived from the optical absorption.

6. The dual-modality imaging system of claim 5, wherein the first generating means comprises laser-generated ultrasound and the second generating means comprises laser-generated optoacoustics, both of said first and second means comprising an ultrawide-band ultrasonic transducer array positioned for acoustic detection of transient pressure waves resulting from delivery of the laser-generated ultrasound and the laser-generated optoacoustics.

7. The dual-modality imaging system of claim 6, wherein the images generated by the laser-generated ultrasound are tomographic images of tissue anatomy, morphology and structure.

8. The dual-modality imaging system of claim 6, wherein the images generated by the laser-generated optoacoustics are tomographic images of tissue functional molecules such as hemoglobin, oxyhemoglobin, water, lipids, proteins and other molecules of biomedical interest.

9. The dual-modality imaging system of claim 6, wherein the images generated by the laser-generated optoacoustics are tomographic images of proteins, nucleic acids, enzymes and other molecules comprising tissue of biomedical interest targeted with exogenous contrast agents or images of a spatial distribution of the exogenous contrast agents, said contrast agents increasing contrast or characterizing molecules, cells or tissues.

10. The dual-modality imaging system of claim 9 wherein said exogeneous contrast agents are optical, optoacoustic, acoustic ultrasonic or dual optoacoustic-ultrasonic contrast agents and said contrast agents are either molecules or nanoparticles.

11. The system of claim 5, wherein all images are spatially coregistered or temporally coregistered.

12. An imaging method for increasing contrast, resolution and accuracy of quantitative information obtained within a subject, comprising the steps of:

a) producing a laser ultrasound or laser optoacoustic image of an outline boundary of a volume of interest within the subject using the dual-modality imaging system of claim 5;

b) generating a spatially or temporally coregistered image of speed of sound and/or an image of ultrasonic attenuation within the outlined volume boundary from information contained in the laser ultrasound or laser optoacoustic image; and

c) generating a spatially or temporally coregistered optoacoustic image based on absorbed optical energy using an algorithm of the image reconstruction that employs distribution of the speed of sound and/or ultrasound attenuation within the outlined volume boundary.

13. A laser optoacoustic ultrasound imaging system (LOUIS), comprising:

a) a dual laser source switchable between a laser ultrasonic mode and a laser optoacoustic mode, said laser source configured to emit either short optical pulses with high repetition rate for the illumination of the ultrasonic emitters in the ultrasonic mode or short optical pulses with lower repetition rate but higher pulse energy for the illumination of the volume of interest in the optoacoustic mode;

b) an imaging module comprising one or more ultrawide-band ultrasonic transducers configured to detect, through a coupling medium, optoacoustic and ultrasonic signals propagated as transient pressure waves from said volume of interest within a subject body;

c) means to rotate and/or translate said imaging module relative to the volume of interest in the subject body to create multiple pressure waves, said means computer controllable or manually controllable;

d) means for processing said detected laser optoacoustic and laser ultrasonic signals and reconstructing processed signals into one or more of anatomical and functional/molecular images of the volume of interest in the subject body.

14. The laser optoacoustic ultrasound imaging system of claim 13, further comprising means for displaying the one or more images or superimposed coregistered images of the subject body or the volume of interest therein.

15. The laser optoacoustic ultrasound imaging system of claim 13, wherein laser optoacoustic illumination is performed in orthogonal mode, backward mode forward mode relative to the subject body or the volume of interest therein.

16. The laser optoacoustic ultrasound imaging system of claim 13, wherein laser ultrasonication is performed in transmission or forward mode or in reflection or backward mode relative to the subject body or the volume of interest therein or in a combination of said modes.

17. The laser optoacoustic ultrasound imaging system of claim 13, wherein the laser wavelength is about 532 nm to about 1064 nm.

18. The laser optoacoustic ultrasound imaging system of claim 13, wherein the one or more ultrawide-band ultrasonic transducers are configured to detect ultrasonic signals with no or minimal reverberations.

19. The laser optoacoustic ultrasound imaging system of claim 13, wherein the transducer array is interchangeable for acquisition of various types of images in order to achieve greater contrast, resolution, or quantitative accuracy of either optoacoustic or ultrasonic images or both.

20. The laser optoacoustic ultrasound imaging system of claim 13, wherein the rotating means is configured to rotate said imaging module, wherein the detecting array of transducers comprises an arc-shaped array or linear flat array or combination of said array shapes comprising small ultrawide-band ultrasonic transducers with wide angular directivity.

21. The laser optoacoustic ultrasound imaging system of claim 13, wherein the translating means is configured to translate said imaging module, wherein the detecting array of transducers comprises an arc-shaped array or linear flat array or combination of said array shapes comprising finite size ultrasonic transducers with narrow angular directivity.

22. The laser optoacoustic ultrasound imaging system of claim 13, wherein the means for processing and reconstructing said detected ultrasonic signals comprises one or more of:

electronic amplifiers with time-gain-control circuits;

multichannel analog-to-digital-converter with a field programmable gate array; and

imaging module design and tomography algorithms configured to reconstruct quantitatively accurate volumetric images.

23. The laser optoacoustic ultrasound imaging system of claim 13, wherein said imaging module comprises a hand-held probe configured for acquisition, reconstruction and display of real-time two-dimensional or three-dimensional images.

24. A method for imaging a subject'"'"'s body or a volume of interest within, comprising the steps of:

a) positioning the subject body within or proximate to the imaging module of the laser optoacoustic ultrasound imaging system of claim 13;

b) delivering a laser-generated pulses of ultrasonic energy to a volume of interest in the subject body;

c) detecting the transmitted or reflected ultrasonic pressure waves while measuring one or more parameters comprising a difference between the time of emission and a time of arrival, a difference between emitted amplitude and detected amplitude, and a difference between ultrasonic frequency spectrum of emitted and detected ultrasonic pulses;

d) delivering a laser-generated pulse of optical energy to a volume of interest in the subject body;

e) detecting the ultrasonic pressure waves generated through optical absorption inside the subject body while measuring one or more parameters comprising a time of arrival relative to a time of generation, an amplitude of detected optoacoustic signals, and an ultrasonic frequency spectrum of detected optoacoustic signals;

f) scanning the subject body or volume of interest therein with a detecting array of ultrawide-band ultrasonic transducers by repeating steps b) to e) at multiple positions around the subject body or volume of interest while simultaneously scanning the sources of optical energy and sources of ultrasonic energy such that relative position of the detecting array of ultrasonic transducers and the sources of optical or ultrasonic energy can change or remain constant during the scans;

g) processing the detected ultrasonic signals to remove distortions of detected signals; and

h) reconstructing one or more volumetric images via mathematical tomography algorithms using data of the processed signals.

25. The method of claim 24, wherein the pulse of optical energy has a duration shorter than the time of pressure wave propagation through the distance in the subject body or volume thereof equal to a desired spatial resolution.

26. The method of claim 24, wherein the scanning step comprises:

a) scanning the whole subject body with a first array of ultrasonic transducers in a rotational configuration to determine at least one volume-of-interest and its characteristics related to absorbed optical energy;

b) replacing the first array with a second array of ultrasonic transducers in a translational configuration; and

c) scanning through said at least one volume-of-interest with a high resolution sufficient to acquire quantitative information related to distribution and concentration of functional molecules therein.

27. The method of claim 24, wherein the one or more volumetric images are either three-dimensional images of the volume of interest or of the subject body, or two-dimensional slices through the three-dimensional volume of interest or even one-dimensional profiles of molecules of interest within the volume.

28. The method of claim 24, wherein at least one volume of interest is a tumor, a lymph node, a vascular circulation network, or a brain.

29. The method of claim 24, wherein laser ultrasound or laser optoacoustic images provide a feedback for guidance of therapeutic treatments or surgical interventions.

30. The optoacoustic imaging method of claim 24, wherein the step of delivering pulsed optical energy is performed at multiple wavelengths of light, whether in sequence or toggling.

31. The optoacoustic imaging method of claim 24, wherein the other energy is electromagnetic energy with a wavelength of about 1 nm to about 1 m.