Quantitative optoacoustic tomography with enhanced contrast

• US 20070238958A1
• Filed: 01/22/2007
• Published: 10/11/2007
• Est. Priority Date: 01/20/2006
• Status: Active Grant

• Current Assignee: Seno Medical Instruments, Inc.
• Original Assignee: Seno Medical Instruments, Inc.
• Inventors: Oraevsky, Alexander, Ermilov, Sergey
• Granted Patent: US 7,740,585 B2
• Time in Patent Office: Days
• US Class Current: 600/407
• CPC Class Codes: A61B 5/0073 by tomography, i.e. reconstruction of 3D images from 2D projections A61B5/0066 takes precedence
• CPC Class Codes: A61B 5/0095 by applying light and detecting acoustic waves, i.e. photoacoustic measurements
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives
• CPC Class Codes: A61B 8/0825 for diagnosis of the breast, e.g. mammography
• CPC Class Codes: A61B 8/406 using means for diagnosing suspended breasts
• CPC Class Codes: A61B 8/483 involving the acquisition of a 3D volume of data
• CPC Class Codes: G01N 2021/1787 Tomographic, i.e. computerised reconstruction from projective measurements
• CPC Class Codes: G01N 21/1702 with opto-acoustic detection, e.g. for gases or analysing solids

Abstract

Provided herein is an optoacoustic imaging system configured to produce images of one or more objects in a body using at least a maximum angular amplitude probability algorithm to reconstruct the optoacoustic images of the body. In addition the optoacoustic imaging system may be configured to produce 3D maps from the reconstructed optoacoustic images of the body. Also, provided is a method for diagnosing a pathophysiological condition characterized by abnormal optical properties of tissues in a body from maps so produced.

Claims

1. An optoacoustic imaging system for producing images of one or more objects in a body, configured to perform the steps of:

a) illuminating a body using pulses of electromagnetic radiation;

b) generating distribution of absorbed thermal energy under illumination conditions of temporal pressure confinement within a volume of a resolution of interest;

c) detecting temporarily resolved profiles of optoacoustic pressure signals resulting therefrom;

d) processing signals to determine a value of absorbed electromagnetic energy; and

e) reconstructing high-contrast quantitative optoacoustic images of the body from determined optical absorption coefficients of one or more objects therewithin using at least a maximum angular amplitude probability algorithm.

2. The optoacoustic imaging system of claim 1, wherein the illuminating step comprises:

delivering pulses of electromagnetic radiation to the body thereby producing a homogeneous distribution of an energy fluence within any given plane or slice inside the body that is perpendicular to the direction of the incident beam of the electromagnetic radiation.

3. The optoacoustic imaging system of claim 1, wherein the detecting step comprises:

a) receiving the optoacoustic signals through an array of ultrawide-band ultrasonic transducers;

or

b) receiving the optoacoustic signals with a single ultrawide-band ultrasonic transducer scanned along the body.

4. The optoacoustic imaging system of claim 1, wherein the processing step comprises:

a) amplifying and digitally recording the temporarily resolved signals using an electronic data acquisition system;

b) filtering all digitally recorded signals from noise while keeping the profiles of the optoacoustic signals unaltered;

c) calculating either an integral of the temporally resolved optoacoustic signals or their time-derivative or a combination thereof resulting in enhanced contrast and optimal signal processing for quantitative analysis; and

d) determining signal amplitude generated by objects only on those ultrasonic transducers that could separate all objects of diagnostic interest by detecting them at different time positions.

5. The optoacoustic imaging system of claim 4, wherein the transducers have a transducer directivity of about 0 to about 2π

steradians and with an angular aperture of the array of about 0 and 4π

steradians.

6. The optoacoustic imaging system of claim 1, wherein the reconstructing step comprises:

a) determining a probability for each sample of the acoustic signal to be received from a particular direction relative to the transducer using a radial backprojection algorithm;

b) applying a maximum angular amplitude probability algorithm effective to use information on the direction of the received acoustic signals relative to the transducer receiving the signal thereby reconstructing the high-contrast quantitative optoacoustic images of the body showing location, shape and true brightness of the one or more objects;

c) fitting each reconstructed arc with a polynomial function and calculating the second derivative to determine exact boundaries of the object(s);

d) assigning each of the determined objects inside the body with an unknown absorption coefficient; and

e) using each sample of the optimally processed temporarily resolved optoacoustic profiles received by each transducer to solve a linear regression model of unknown absorption coefficients with regression coefficients related to determined sizes of the one or more objects.

7. The optoacoustic imaging system of claim 6, wherein the object is a single object and step e) comprises:

a) using each sample of the integral of the temporarily resolved optoacoustic profiles received by each transducer to calculate an average absorption coefficient of an arc inside the object while accounting for individual size of the image pixel and the number of pixels in the arc within the object; and

b) using statistical distribution of the average absorption coefficients of the arcs to estimate the true absorption coefficient of the object.

8. The optoacoustic imaging system of claim 6, wherein the directivity of each transducer is about zero and step e) comprises:

placing measured sample values of the integrated optoacoustic signals to the pixels of the map along the line of directivity of each acoustic transducer.

9. The optoacoustic imaging system of claim 1, further configured to perform the step of:

plotting a map of the one or more objects using the determined optical absorption coefficients.

10. The optoacoustic imaging system of claim 9, wherein the map of the one or more objects comprises a tool for a diagnosis of a pathophysiological condition of the body characterized by abnormal optical properties of tissues or to establish the location and the absolute value of the same.

11. The optoacoustic imaging system of claim 10, wherein the pathophysiological condition is a breast cancer, a prostate cancer, skin cancer, a vascular skin disorder, a brain hemorrhage, a hematoma, a heart disease, atherosclerotic plaques, arthritis, an ocular disease, any tissue deprived from blood supply due to the pathophysiological condition or other condition with abnormal optical properties of tissues.

12. An optoacoustic imaging system for producing maps of one or more objects in a body, configured to perform the steps of:

a) illuminating the body with pulses of electromagnetic radiation thereby producing a homogeneous distribution of an energy fluence within any given plane inside the body perpendicular to the direction of the incident beam of the electromagnetic radiation;

b) detecting temporarily resolved profiles of resulting optoacoustic signals using an array of ultrawide-band ultrasonic transducers with transducer directivity of about 0 to about 2π

steradians and with an angular aperture of the array of about 0 and 4π

steradians;

c) amplifying and digitally recording the temporarily resolved signals using an electronic data acquisition system;

d) filtering all digitally recorded signals from noise while keeping the profiles of the optoacoustic signals unaltered;

e) optimally processing the temporalily resolved signals to convert bipolar pressure signals into monopolar signals with amplitude proportional to the absorbed thermal energy;

f) reconstructing optoacoustic images of the body using a radial backprojection algorithm effective to determine a probability for each sample of an optoacoustic signal to be received from a particular direction relative to the transducer;

g) applying a maximum angular amplitude probability algorithm effective to use information on the direction of the received optoacoustic signals relative to the transducer thereby reconstructing high-contrast optoacoustic images of the body showing location and shape of the one or more objects;

h) fitting each reconstructed arc with a polynomial function and calculating the second derivative to determine exact boundaries of the object(s);

i) assigning each of the determined objects inside the body with an unknown absorption coefficient;

j) using each sample of the integral of the temporarily resolved optoacoustic profiles received by each transducer to solve a linear regression model of unknown absorbtion coefficients with regression coefficients related to determined sizes of the objects; and

k) plotting the optoacoustic map based on determined absorption coefficients of the one or more objects inside the body.

13. The optoacoustic imaging system of claim 12, wherein the object is a single object and step i) comprises:

a) using each sample of the integral of the temporarily resolved optoacoustic profiles received by each transducer to calculate an average absorption coefficient of an arc in the object while accounting for individual size of the image pixel and the number of pixels in the arc within the object; and

b) using statistical distribution of the average absorption coefficients of the arcs to estimate the true absorption coefficient of the object.

14. The optoacoustic imaging system of claim 12, wherein the directivity of each transducer is about zero, and step 1) comprises:

reconstructing the optoacoustic images of the body by placing measured sample values of the integrated optoacoustic signals to the pixels of the map along the line of directivity of each acoustic transducer.

15. The optoacoustic imaging system of claim 12, wherein the map of the one or more objects comprises a tool for diagnosis of a pathophysiological condition of the body characterized by abnormal optical properties of tissues or to establish the location and absolute value of the same.

16. The optoacoustic imaging system of claim 15, wherein the pathophysiological condition is a breast cancer, a prostate cancer, skin cancer, a vascular skin disorder, a brain hemorrhage, a hematoma, a heart disease, atherosclerotic plaques, arthritis, an ocular disease, any tissue deprived from blood supply due to the pathophysiological condition or other condition with abnormal optical properties of tissues.

17. A method for diagnosing a pathophysiological condition characterized by abnormal optical properties of tissues in a body, comprising:

a) obtaining temporarily resolved profiles of acoustic signals generated by one or more objects associated with the pathophysiological condition within a body upon illumination thereof with electromagnetic radiation;

b) applying at least a maximum angular amplitude probability algorithm to the profiles to determine optical absorption coefficients of the one or more objects to reconstruct high-contrast optoacoustic images of the body; and

c) plotting an optoacoustic map based on the determined optical absorption coefficient(s) of the object(s) showing a location thereof inside the body thereby diagnosing the pathophysiological condition.

18. The method of claim 17, wherein the electromagnetic radiation is pulsed thereby producing a homogeneous distribution of an energy fluence within any given plane or slice inside the body that is perpendicular to the direction of the incident beam of the electromagnetic radiation.

19. The method of claim 17, wherein the obtaining step comprises:

a) receiving the acoustic signals through an array of ultrawide-band ultrasonic transducers;

b) amplifying and digitally recording the temporarily resolved signals using an electronic data acquisition system; and

c) filtering all digitally recorded signals from noise while keeping the profiles of the acoustic signals unaltered.

20. The method of claim 19, wherein the transducers have a transducer directivity of about 0 to about 2π

steradians and with an angular aperture of the array of about 0 and 4π

steradians;

21. The method of claim 17, wherein the applying step comprises:

a) determining a probability for each sample of the acoustic signal to be received from a particular direction relative to the transducer using a radial backprojection algorithm;

b) applying a maximum angular amplitude probability algorithm effective to use information on the direction of the received acoustic signals relative to the transducer receiving the signal thereby reconstructing the high-contrast optoacoustic images of the body showing location and shape of one or more objects;

c) fitting each reconstructed arc with a polynomial function and calculating the second derivative to determine exact boundaries of the object(s);

d) assigning each of the determined objects inside the body with an unknown absorption coefficient; and

e) using each sample of the integral of the temporarily resolved optoacoustic profiles received by each transducer to solve a linear regression model of unknown absorption coefficients with regression coefficients related to determined sizes of the objects.

22. The method of claim 21, wherein the object is a single object and step e) comprises:

a) using each sample of the integral of the temporarily resolved optoacoustic profiles received by each transducer to calculate an average absorption coefficient of an arc in the object while accounting for individual size of the image pixel and the number of pixels in the arc within the object; and

b) using statistical distribution of the average absorption coefficients of the arcs to estimate the true absorption coefficient of the object.

23. The method of claim 21, wherein directivity of each transducer is about zero and step e) comprises:

placing measured sample values of the integrated optoacoustic signals to the pixels of the map along the line of directivity of each acoustic transducer.

24. The method of claim 17, further comprising:

administering an optoacoustic contrast agent effective to alter optical absorption of specific objects or locations of diagnostic interest in the body.

25. The method of claim 17, wherein the pathophysiological condition is a breast cancer, a prostate cancer, skin cancer, a vascular skin disorder, a brain hemorrhage, a hematoma, a heart disease, atherosclerotic plaques, arthritis, an ocular disease, any tissue deprived from blood supply due to the pathophysiological condition or other condition with abnormal optical properties of tissues.