SYSTEMS AND METHODS FOR COMPONENT SEPARATION IN MEDICAL IMAGING

• US 20150101411A1
• Filed: 10/13/2014
• Published: 04/16/2015
• Est. Priority Date: 10/11/2013
• Status: Active Grant

• Current Assignee: Seno Medical Instruments, Inc.
• Original Assignee: Seno Medical Instruments, Inc.
• Inventors: Zalev, Jason, Clingman, Bryan, Herzog, Donald G.
• Granted Patent: US 10,309,936 B2
• Time in Patent Office: Days
• US Class Current: 73/643
• CPC Class Codes: A61B 2560/0223 of calibration, e.g. protocols for calibrating sensors
• 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 5/0066 Optical coherence imaging
• CPC Class Codes: A61B 5/0095 by applying light and detecting acoustic waves, i.e. photoacoustic measurements
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• CPC Class Codes: A61B 8/4281 characterised by sound-transmitting media or devices for coupling the transducer to the tissue
• 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: G01N 2291/023 Solids
• CPC Class Codes: G01N 2291/02475 Tissue characterisation
• CPC Class Codes: G01N 29/0654 Imaging
• CPC Class Codes: G01N 29/2418 using optoacoustic interaction with the material, e.g. laser radiation, photoacoustics photoacoustic cells G01N21/1702; measuring characteristics of vibrations by using radiation-sensitive means G01H9/00; acousto-optical conversion techniques for short-range imaging G01S15/8965; sound-producing devices using laser bundle G10K15/046
• CPC Class Codes: G16H 30/40 for processing medical images, e.g. editing
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

A system is provided for component separation. In an embodiment, a light source or other source of electromagnetic energy delivers energy to a volume of tissue. A transducer array or other sensor receives a resulting acoustic signal, and a processing subsystem processes the acoustic signal to separate a direct acoustic return component from a secondary acoustic return component of the acoustic signal. An output and/or storage device presents and/or stores information about the direct acoustic return component, the secondary acoustic return component, or both. Other embodiments include a coded probe, a probe having an isolator that produces a wavefront, a sensor for measuring intensity of an acoustic wave produced by absorbed photons, and a system that receives acoustic signals from surface targets to determine an optical parameter of the volume.

Claims

1. A medical imaging system, comprising:

at least one light source for delivering light energy to a volume of tissue;

a transducer array for receiving an acoustic signal in response to the delivery of light energy, the acoustic signal comprising at least a direct acoustic return component and a secondary acoustic return component, the secondary acoustic return component comprising an acoustic response that is substantially reflected or scattered before arriving at the transducer array;

a processing subsystem for processing the acoustic signal to separate the direct acoustic return component from the secondary acoustic return component of thereof; and

,

an output device for presenting information about at least one of the direct acoustic return component and the secondary acoustic return component.

2. The medical imaging system according to claim 1, wherein the output device comprises a display for displaying an image that utilizes the information about the direct acoustic return component, the secondary acoustic return component, or both.

3. The medical imaging system according to claim 1, wherein the output device comprises a storage device for storing the information about the direct acoustic return component, the secondary acoustic return component, or both.

4. The medical imaging system according to claim 1, wherein the processing subsystem comprises:

a sub-module for simulating secondary acoustic return signals from secondary acoustic return spatial representations;

a sub-module for simulating direct acoustic return signals from direct acoustic return spatial representations;

a sub-module for reconstructing secondary acoustic return spatial representations from secondary acoustic return signals; and

,

a sub-module for reconstructing direct acoustic return spatial representations from direct acoustic return signals.

5. The medical imaging system according to claim 4, wherein the processing subsystem is configured to apply a point spread function to a current estimate of a direct acoustic return representation and a current estimate of a secondary acoustic return representation.

6. The medical imaging system according to claim 5, wherein the point spread function is applied according to steps comprising:

simulating the current direct acoustic return estimate to produce a direct acoustic return sinogram using the direct acoustic return simulation sub-module;

simulating the current secondary acoustic return estimate to produce a secondary acoustic return sinogram using the direct acoustic return simulation sub-module;

adding the direct acoustic return sinogram to the secondary acoustic return sinogram to produce an overall sinogram;

reconstructing direct acoustic return from the overall sinogram to produce a direct acoustic return PSF representation using the direct acoustic return reconstruction sub-module; and

,

reconstructing secondary acoustic return from the overall sinogram to produce a secondary acoustic return PSF representation using the secondary acoustic return reconstruction sub-module.

7. The medical imaging system according to claim 4, wherein the processing subsystem is configured to execute a process for component separation, comprising the steps of:

a) producing a reference representation for direct acoustic return and a reference representation for secondary acoustic return by reconstructing the recorded acoustic return signals using the direct acoustic return sub-module and the secondary acoustic return sub-module; and

,

b) computing at least one iteration comprising the steps of;

i) applying a point spread function to current estimates of direct acoustic return and secondary acoustic return;

ii) computing residuals between the reference representations and PSF representations;

iii) multiplying the residuals by a weight to give weighted residuals;

iv) adding the weighted residuals to the current estimates of direct acoustic return and secondary acoustic return; and

,

v) applying thresholding to produce the next estimates of direct acoustic return and secondary acoustic return.

8. The medical imaging system according to claim 4, further comprising:

a sub-module for computing a residual between a simulated estimate of electromagnetically absorbent targets within the volume and a reference based on recorded direct acoustic return signals;

a sub-module for computing a residual between a simulated estimate of acoustically reflective targets within the volume and a reference based on recorded secondary acoustic return signals;

a sub-module for modifying the estimates of the targets based on computed residuals; and

,

a sub-module for outputting final estimates of spatial or signal representations of the targets.

9. The medical imaging system according to claim 1, further comprising a probe with a distal surface, wherein the acoustic impedance of at least a portion of the distal surface is acoustically mismatched to the volume of tissue and the secondary acoustic return component comprises reflections from targets in the volume by a wavefront originating proximate to the distal surface, the wavefront produced as a result of the acoustic mismatch following the light delivery.

10. The medical imaging system according to claim 4, wherein the direct acoustic return simulation sub-module and direct acoustic return reconstruction sub-module use delays based on voxel to transducer element distances, and wherein the secondary acoustic return simulation sub-module and secondary acoustic return reconstruction sub-module use delays based on wavefront source to voxel to transducer element distances.

11. A medical imaging system, comprising:

at least one light source for delivering light energy to a volume of tissue;

a transducer array for receiving a resulting acoustic signal;

a processing subsystem for processing the acoustic signal to identify a secondary acoustic return component of the acoustic signal, and to determine at least a portion of a boundary of a region of the tissue using the secondary acoustic return component of the acoustic signal; and

,

an output device for presenting information about at least one of a direct acoustic return component and the secondary acoustic return component.

12. The medical imaging system according to claim 11, wherein the processing subsystem uses the determined boundary to mitigate at least a portion of the direct acoustic return component.

13. The medical imaging system according to claim 11, further comprising a probe configured with features to produce at least one acoustic wavefront directed to propagate into the volume of tissue resulting from delivery of the light energy, wherein the at least one produced acoustic wavefront contributes to the used information of the secondary acoustic return component.

14. A system, comprising:

a light source adapted to produce light at a first predominant wavelength and at a second predominant wavelength;

a light path adapted to deliver the light from the light source toward an exit port, the exit port positioned to permit the delivery of light to a volume containing acoustic scatterers;

a surface adapted to be acoustically coupled to the volume, the surface comprising a first feature and a second feature, wherein the first feature produces a wavefront that is stronger in response to light at the first predominant wavelength than the wavefront the first feature produces in response to light at the second predominant wavelength, and the second feature produces a wavefront in response to light at the second predominant wavelength that is at least as strong as the wavefront the second feature produces in response to light at the first predominant wavelength;

an array of acoustic receivers that receive acoustic signals produced in response to light from the light source, wherein the acoustic signals received in response to the first predominant wavelength comprise a direct acoustic return from the volume and a secondary acoustic return from scattered wavefronts produced, at least in part, by the first feature and the second feature, and wherein the acoustic signals received in response to the second predominant wavelength comprise a direct acoustic return from the volume and a secondary acoustic return from scattered wavefronts produced, at least in part, by the first feature and the second feature;

a processing subsystem configured to perform steps comprising;

computing a spatial representation of a volume from the acoustic signals received in response to the first predominant wavelength and the acoustic signals received in response to the second predominant wavelength, the spatial representation reflecting a chromophore distribution in the volume, wherein the secondary acoustic return for the first predominant wavelength and the secondary acoustic return for the second predominant wavelength contribute to a distortion in the spatial representation, the contribution to the distortion for the first predominant wavelength has a distinguishable difference from the contribution to the distortion for the second predominant wavelength; and

,

mitigating the secondary acoustic return at the first predominant wavelength and the secondary acoustic return at the second predominant wavelength to substantially prevent the distortion in the spatial representation from appearing in a produced output image, wherein the output image is based on the spatial representation, and the output image comprises regions indicating the presence of the chromophore.

19. The system of claim 14, wherein substantially all of the light that reaches the first feature passes through the volume and exits the volume prior to reaching the first feature, and wherein substantially all of the light that reaches the second feature passes through the volume and exits the volume prior to reaching the second feature.

20. The system of claim 14, wherein the step of mitigating the effect of the secondary acoustic return at the first predominant wavelength and the secondary acoustic return at the second predominant wavelength comprises a first processing mode for the first predominant wavelength and a second processing mode for the second predominant wavelength, wherein the first processing mode and the second processing mode differ by at least a parameter.

21. The system of claim 20, wherein the step of mitigating the distortion is facilitated by the distinguishable difference between the contribution to the distortion of the first predominant wavelength and the contribution to the distortion of the second predominant wavelength.

22. The system of claim 14, wherein the processing subsystem is configured to perform steps further comprising:

deconvolving the secondary acoustic return of the first predominant wavelength with an optical energy impulse response of the first predominant wavelength; and

,

deconvolving the secondary acoustic return of the second predominant wavelength with an optical energy impulse response of the second predominant wavelength, to further prevent the distortion in the spatial representation from appearing in a produced output image.

23. The system of claim 22, wherein the processing subsystem is configured to perform steps further comprising:

deconvolving the direct acoustic return of the first predominant wavelength with the optical energy impulse response of the first predominant wavelength; and

,

deconvolving the direct acoustic return of the second predominant wavelength with the optical energy impulse response of the second predominant wavelength.

24. The system of claim 14, wherein the step of mitigating the effect of the secondary acoustic return at the first predominant wavelength and the secondary acoustic return at the second predominant wavelength comprises identifying the contribution to the distortion for the first predominant wavelength and the contribution to the distortion for the second predominant wavelength.

25. The system of claim 24, wherein the distinguishable difference in the contribution to the distortion is used in identifying the contributions for the first predominant wavelength and the second predominant wavelength.

26. The system of claim 14, wherein the surface, the acoustic receivers, and the exit port reside on a handheld probe.

27. The system of claim 14, wherein the processing subsystem further comprises the step of computing an image representing the spatial distribution of acoustic scatterers in the volume based on, at least in part, the secondary acoustic return for the first predominant wavelength.

15. The system of 14, wherein the surface further comprises an optically reflective material that covers at least a portion of the surface.

16. The system of 14, wherein the optically reflective material is a coating.

17. The system of 14, wherein the surface further comprises a pattern to produce a predictable wavefront, and the pattern is comprised of the first feature and at least one copy of the first feature.

18. The system of 17, wherein the pattern is further comprised of the second feature and at least one copy of the second feature.

28. An opto-acoustic probe having a distal end, the probe comprising:

a light path adapted to direct light from a light input toward the distal end of the probe;

a light exit port at the distal end of the probe for the light to be directed into a volume to produce direct acoustic return signals;

an ultrasound receiver to receive acoustic signals;

an optically reflective portion on an outer surface; and

,

at least one opto-acoustic target on the outer surface, the opto-acoustic target adapted to generate acoustic wavefronts in response to the light, which acoustic wavefronts upon scattering within the volume produce scattered acoustic waves that can be detected by the ultrasound receiver and identified as secondary acoustic return when processed by a processing subsystem.

29. The opto-acoustic probe of claim 28, wherein the at least one opto-acoustic target is more optically absorbing than the optically reflective portion on the outer surface.

30. The opto-acoustic probe of claim 28, wherein the optically reflective portion on the outer surface is a coating.

31. The opto-acoustic probe of claim 28, wherein a patterned arrangement of the at least one opto-acoustic targets on the outer surface is a coding.

32. The opto-acoustic probe of claim 28, wherein the identified secondary acoustic return is distinguishable as one or more recognizable artifacts in processed representations created from the received acoustic signals.

33. The opto-acoustic probe of claim 32, wherein the one or more recognizable artifacts can be recognized by computer processing without substantially distorting a produced direct acoustic return image to be perceived by a human.

34. The opto-acoustic probe of claim 28, wherein the identified secondary acoustic return is used to produce an ultrasound image, which can be separately displayed or co-registered with a direct acoustic return image.

35. A system, comprising:

an energy source configured to deliver electromagnetic energy to a volume comprising one or more acoustic targets;

a probe with an outer surface to form a coupling interface between itself and a surface of the volume;

one or more elements on the outer surface of the probe to produce a predictable wavefront pattern originating substantially at the coupling interface as a result of the delivered energy; and

,

an acoustic receiver to receive an acoustic return comprising direct acoustic return signals and secondary acoustic return signals, the secondary acoustic return signals comprising at least a portion of the predictable wavefront pattern that is scattered by the one or more acoustic targets; and

,

a processing subsystem that uses a received wavefront resulting from the predictable wavefront pattern in connection with producing an output.

36. The system of claim 35, wherein the coupling interface is coupled using a coupling medium.

37. The system of claim 35, wherein the processing subsystem is configured to use the received wavefront by forming a direct acoustic return representation with a distinguishable secondary acoustic return component.

38. The opto-acoustic probe of claim 37, configured such that the distinguishable secondary acoustic return component can be recognized by computer processing without substantially distorting a produced direct acoustic return image to be perceived by a human.

39. The opto-acoustic probe of claim 36, wherein the secondary acoustic return component is used to produce an image separate from a produced direct acoustic return image.

40. The system of claim 35, wherein the one or more featured elements comprises an optically absorbing line source.

41. The system of claim 40, wherein the optically absorbing line source meets with other optically absorbing line sources to form a rectangle.

42. The system of claim 35, wherein the predictable wavefront pattern resulting from featured elements on the outer surface of the probe comprises a wavefront produced by an air-tissue interface surrounding the outer surface.

43. The system of claim 35, wherein the received secondary acoustic return signals are used to produce an image, which can be separately displayed or co-registered with a direct acoustic return image.

44. An opto-acoustic probe, comprising:

a transducer assembly;

a light path to transmit energy from a light input towards a distal end of the probe;

an exit port for the light to exit the distal end of the probe;

an isolator to reduce the amount of energy transmitted from the light path to the transducer assembly, wherein an outer surface at the distal end of the probe comprises a surface of the isolator and the surface of the isolator comprises at least a portion having an optically reflective coating and the outer surface comprises a portion that is substantially less optically reflective than the optically reflective coating.

45. The probe of claim 44, wherein the at least a portion of the surface of the isolator that is substantially less optically reflective is configured to produce an acoustic wavefront in response to the light, which wavefront will reflect off of acoustically reflective portions in a volume to produce a secondary acoustic return signal that can be received by the transducer assembly.

46. The probe of claim 45, wherein the optically reflective coating of the isolator substantially reduces wavefronts produced on coated portions of the optical isolator.

47. The probe of claim 45, wherein the surface of the isolator comprises the at least a portion of the outer surface that is substantially less optically reflective and the coating of the isolator surface forms a pattern that causes the produced acoustic wavefront to be substantially predictable.

48. The probe of claim 44, wherein the isolator substantially absorbs acoustic energy and the isolator substantially absorbs optical energy.

49. The probe of claim 44, wherein the isolator substantially absorbs acoustic energy and the isolator substantially reflects optical energy.

50. The probe of claim 45, wherein features of the isolator surface lie parallel to an array of acoustic receivers in the transducer assembly causing a substantially filterable stripe interference in a received signal.

58. The sensor of claim 46, wherein multiple photon absorbing elements are patterned into produced acoustic surface wave codes.

51. A sensor to interrogate a volume, the sensor comprising:

acoustic receiver;

photon exit port through which photons pass as they are delivered into the volume;

photon absorbing element positioned a distance away from the exit port configured to absorb photons that have traveled through the volume;

wave propagation medium external to the volume and proximate to the photon absorbing element and the acoustic receiver to permit an acoustic wave produced by the photon absorbing element to propagate from the photon absorbing element to the acoustic receiver; and

,

electrical path for connecting the acoustic receiver to be sampled by an acquisition system.

52. The sensor of claim 51, wherein the photon absorbing element comprises a first optical absorption coefficient for a first predominant wavelength of photons delivered to the volume, and second optical absorption coefficient for a second predominant wavelength of photons delivered to the volume.

53. The sensor of claim 51, further comprising an additional photon absorbing element, wherein the photon absorbing element has a substantially different optical absorption coefficient at a first predominant wavelength of photons delivered to the volume than an optical absorption coefficient of the additional photon absorbing element at the first predominant wavelength, and wherein the wave propagation medium further permits an acoustic wave produced by the additional photon absorbing element to propagate from the additional absorbing element to the acoustic receiver.

54. The sensor of claim 51, wherein the wave propagation medium is a surface that has been coated with a coating.

55. The sensor of claim 54, wherein the coating has been applied on top of a highly acoustically absorbing medium.

56. The sensor of claim 54, wherein the photon absorbing element is placed on top of the coating.

57. The sensor of claim 56, wherein the coating is an optically reflective coating.

59. The sensor of claim 51, wherein the sensor operates on a distal surface of an opto-acoustic probe, wherein the distal surface of the opto-acoustic probe acoustically couples to the volume using a coupling medium, and wherein the photons delivered to the volume can pass through the coupling medium.

60. A system, comprising:

a source of electromagnetic energy configured to produce more than one energy events in an acquisition frame, the energy events occurring at different times, each energy event comprising electromagnetic energy to be delivered to a volume;

at least one acoustic receiver configured to receive acoustic signals from the volume;

a data acquisition unit adapted to sample the at least one acoustic receiver during a period of time following a triggering event to record the acquisition frame, wherein the acquisition frame comprises multiple components, the multiple components comprising interfering direct acoustic return signals resulting from the more than one energy events, wherein a first of the interfering direct acoustic return signals of a first of the more than one energy events contributes to interference in the acquisition frame with at least one other of the interfering direct acoustic return signals of at least one other of the more than one energy events;

a data processing subsystem comprising a component separation module configured to separate the interfering direct acoustic return signals; and

,

a display device for displaying data derived from at least one of the separated multiple components.

61. The system of claim 60, wherein the triggering events are produced by a control unit to demarcate the acquisition frame among a set of multiple acquisition frames.

62. The system of claim 60, wherein a first of the more than one energy events is of a first predominant wavelength, and wherein a second of the more than one energy events is of a second predominant wavelength.

63. The system of claim 62, wherein the energy events of the acquisition frame are of a first predominant wavelength, and wherein the energy events of another acquisition frame in the set of multiple acquisition frames are of a second predominant wavelength.

64. The system of claim 60, wherein the multiple components further comprise components selected from the group consisting of:

direct acoustic return, secondary acoustic return, produced acoustic backscatter, acoustic surface wave, produced acoustic surface wave, and an additional component; and

wherein the component separation module is further configured to separate the multiple components.

65. The system of claim 60, further comprising:

a probe with a distal surface wherein the at least one acoustic receiver is located on the distal surface of probe; and

,

an output port on the distal surface of the probe for delivering the electromagnetic energy to the volume and the electromagnetic energy is light energy, and the energy events each comprise a pulse of light.

66. A method, comprising:

depositing light energy directed through an exit port of a light path into an optically scattering volume, where a portion of the light energy that exits the exit port of the light path follows a sequence comprising entering the volume, scattering within the volume and exiting the volume;

receiving acoustic signals originating from targets positioned proximate to a surface of the volume, wherein the targets absorb at least a portion of the portion of the light energy that has followed the sequence to exit the volume;

analyzing the received acoustic signals to determine an intensity of the absorbed at least a portion of the portion of the light that has followed the sequence; and

,

determining at least one optical parameter of the volume based on the analyzed received acoustic signals.

67. The method of claim 66, wherein the targets are located on a distal surface of an opto-acoustic probe, and the probe comprises acoustic receivers for receiving the received acoustic signals.

68. The method of claim 67, wherein the probe is acoustically coupled proximate to the surface of the volume.

69. The method of claim 66, wherein the step of analyzing comprises creating a representation of light absorbed by the targets by computing intensity for a spatial position corresponding to at least one of the targets by using the received acoustic signal at time delays corresponding to wavefront propagation delay of the spatial position.

70. The method of claim 69, wherein creating a representation of light absorbed by the targets comprises reconstructing an image of a surface comprising the targets.

71. The method of claim 70, wherein reconstructing the image comprises separating a produced acoustic surface wave component from another component.

72. The method of claim 66, where the targets are arranged in a pattern.

73. The method of claim 72, wherein the arranged targets are lines arranged in a rectangle.

74. The method of claim 66, wherein the at least one optical parameter is selected from the group consisting of:

an optical absorption coefficient, an optical scattering coefficient, and an optical isotropy parameter.

75. The method of claim 66, wherein the step of determining comprises finding a fitted solution to a fluence model of the light in the volume.

76. The method of claim 66, further comprising the steps of:

producing a fluence compensation curve by using the determined at least one optical parameter;

using the fluence compensation curve to compensate an opto-acoustic image spatially representing opto-acoustic sources within the volume; and

,

outputting the compensated opto-acoustic image.

77. A method, comprising:

placing a surface of a probe proximate to a surface of a volume;

delivering light from a light source to the volume, wherein a portion of the light from the light source is absorbed by patterns on the surface of the probe;

receiving acoustic signals from the volume, wherein the received acoustic signals comprise components of acoustic signal resulting from scattering of wavefronts produced by the patterns on the surface of the probe in response to absorbing the portion of the light;

processing the received acoustic signals to identify a component that resulted due to scattering by a target at a first position in the volume, wherein a first acoustic front due to the patterns on the surface of the probe targeting the first position in the volume is distinguishably different from a second acoustic front due to the patterns on the surface of the probe targeting a second position in the volume, wherein a scattered component of a target at the second position interferes with the component of the received acoustic signal that resulted due to scattering by the target at the first position, and wherein prediction of acoustic fronts due to the patterns on the surface of the probe reaching positions in the volume is used to identify the component; and

,

outputting an intensity of the identified component at the first position in the volume.

78. The method of claim 77, wherein the received acoustic signals are received by at least one receiver located on the surface of the probe and the surface of the probe further comprises at least one exit port to deliver the light from the light source to the volume, wherein a portion of the light from the light source exiting the exit port is absorbed by optically absorbing targets in the volume.

79. The method of claim 77, further comprising forming an image of a portion of the volume, wherein the image comprises voxels and a voxel of the image is computed by computing a voxel intensity that is outputted by the step of outputting wherein the first position in the volume corresponds to the position of the voxel.

80. The method of claim 79, wherein the second position in the volume in computing the computed voxel intensity corresponds to a position in the volume that is outside of the imaged portion of the volume and thus does not correspond to a voxel in the image.

81. The method of claim 79, wherein the step of forming an image of a portion of the volume comprises performing an iterative process comprising:

simulating received signals from a target at one position and from an interfering target at another position to produce simulated signals; and

,

reconstructing a spatial representation of the volume from the simulated signals.

82. The method of claim 81, wherein the received acoustic signals are received by an array of receivers incident with an imaging plane partitioning the volume and the method is used to suppress out-of-plane objects in the image and the portion of the volume in the image is within the imaging plane.

83. The method of claim 79, further comprising:

receiving direct acoustic return from the volume;

forming a direct acoustic return spatial representation of the volume from the received direct acoustic return;

using the formed image to identify and suppress out-of-plane objects in the direct acoustic return spatial representation; and

,

displaying the direct acoustic return spatial representation on a display.

84. The method of claim 79, further comprising displaying the image on a display.

85. A method, comprising:

placing an opto-acoustic probe in proximity to a surface of a volume of tissue, the volume of tissue comprising an epidermal layer;

delivering optical energy into the volume of tissue, wherein a portion of the optical energy is absorbed by the epidermal layer thus producing an upward directed response and a downward directed response;

receiving acoustic signals from a receiver coupled to the surface of the volume of tissue, wherein the received acoustic signals comprise;

a direct acoustic return component from the upward directed response of the epidermal layer; and

,

a secondary acoustic return component corresponding to an acoustic reflection of the downward directed response of the epidermal layer by a target in the volume;

processing the received acoustic signals to produce processed signals;

analyzing the processed signals to determine an auxiliary signal from the direct acoustic return component;

using the auxiliary signal to compute an output from the processed signals pertaining to the secondary acoustic return component; and

,

outputting and image based on the computed output to a display.

86. The method of 85, wherein the step of using the auxiliary signal to compute an output from the processed signals pertaining to the secondary acoustic return component comprises performing an operation on the secondary acoustic return component using the auxiliary signal as a response function, wherein the operation is selected from the group consisting of:

deconvolution, detection or separation.

87. A method, comprising:

acquiring signals for a first frame using an opto-acoustic probe;

processing data from the signals of the first frame to compute a detected one or more vessels in the first frame;

determining configurations of the detected one or more vessels of the first frame, wherein the determined configurations are stored in a data structure;

acquiring signals for an adjacent frame using the opto-acoustic probe;

processing data from the signals of the adjacent frame to compute a detected one or more corresponding vessels in the adjacent frame, wherein the detected one or more corresponding vessels of the adjacent frame correspond to the detected one or more vessels of the first frame;

solving for a motion between the first frame and the adjacent frame;

using the solved motion between the first frame and the adjacent frame to compute a representation of an inter-frame movement of the opto-acoustic probe; and

,

outputting the inter-frame movement undergone by the opto-acoustic probe.

88. The method of claim 87, wherein the opto-acoustic probe is a handheld opto-acoustic probe, the method further comprising the steps of:

delivering optical energy to a volume of tissue to produce the opto-acoustic signals for the first frame; and

,

delivering second optical energy to the volume of tissue to produce the opto-acoustic signals for the adjacent frame.

89. The method of claim 88, the method further comprising the steps of:

forming an image of the detected one or more vessels of the first frame overlayed on top of another image; and

,

outputting the formed image to a display.

90. The method of claim 87, wherein the determined configurations comprise parameters selected from the group consisting of:

vessel position or vessel orientation.

91. The method of claim 87, wherein the data structure used to store the configurations models a representation selected from the group consisting of:

a vascular tree, a vascular network, tissue regions, or vascular segments.

92. The method of claim 87, wherein solving for the motion between the first frame and the adjacent frame comprises finding a transformation that maps the configurations of the detected one or more vessels of the first frame to the detected one or more corresponding vessels of the adjacent frame.

93. The method of claim 92, further comprising the step of determining positions of the detected one or more corresponding vessels of the adjacent frame, and wherein the step of solving for the motion between the first frame and the adjacent frame comprises finding a location of an unknown plane by matching the positions of the detected one or more corresponding vessels of the adjacent frame to intersections of lines representing the detected one or more vessels of the first frame.

94. A method, comprising:

placing an opto-acoustic probe comprising a distal surface into contact with a surface of a volume to form a coupling interface, wherein the distal surface comprises a detector array;

delivering energy to the volume;

receiving acoustic signals comprising;

a direct component due to acoustic return signals produced within the volume; and

,

a surface component due to an acoustic wavefront propagating substantially proximate to the distal surface where the wavefront reaches elements of the detector array in a sequence, wherein the surface component varies according to at least one parameter that is dependent on properties of the coupling interface or materials proximate thereto;

processing the acoustic signals to determine the at least one parameter;

forming an image using the acoustic signals that is spatially representative of the volume, wherein formation of the image is dependent on the at least one parameter; and

,

outputting the image to a display.

95. The method of claim 94, wherein the elements of the detector array are aligned in a row and spaced equidistantly so that the acoustic signals arrange to form a sinogram with the surface component presented substantially as a diagonal line, the step of processing further comprising a step selected from the group consisting of:

using slope of the diagonal line to infer a speed of sound;

using an intercept of the at least one diagonal line to infer the position of origin of a wavefront; and

,

using change of intensity of the at least one diagonal line to infer an attenuation coefficient.

96. The method of claim 94, wherein the parameter is selected from the group consisting of:

a shear wave velocity or sound speed;

a longitudinal wave velocity or sound speed;

a coupling medium thickness;

a status of whether the probe is in contact with the volume;

a position beyond which the distal surface is not in contact with the volume;

a thickness of an epidermal layer;

a mechanical property of the coupling interface;

a position where a surface wavefront originates;

a parameter for mitigating an artifact;

an attenuation coefficient;

or,

an acoustic impedance.

97. The method of claim 94, wherein the wavefront is produced at a discontinuity of a feature of the probe.

98. The method of claim 97, wherein the discontinuity is of a property selected from the group consisting of:

optical absorption and acoustic impedance.

99. The method of claim 94, wherein a portion of the surface of the volume that is not in contact with the opto-acoustic probe is exposed to air, and the discontinuity is at a boundary where probe, air and tissue meet.

100. The method of claim 97, wherein formation of the image comprises the step of mitigating the surface component so that an artifact from the surface component is not displayed in the image.

101. A system, comprising:

a light source configured to deliver light energy along a light path towards an energy exit port, the energy exit port is positioned at a distal end of the light path to permit energy to exit the light path, the exit port is configured to be coupled to a volume to deliver energy comprising acoustic energy to the volume, wherein a surface in the light path that is proximate to the energy exit port comprises a plurality of optically interacting modes, each optically interacting mode is configured to interact with the light energy in the light path, the optically interacting modes are selected from the group consisting of;

i) optically reflective mode to substantially reflect light energy and produce substantially no acoustic energy response;

ii) optically absorbing mode to substantially absorb light energy and produce an acoustic energy response, wherein a portion of the produced acoustic energy exits the energy port; and

,

iii) optically transparent mode to substantially transmit light energy and produce substantially no acoustic energy response, wherein the transmitted light energy exits the energy exit port; and

,

wherein the plurality of optically interacting modes are arranged to comprise a pattern to permit shaping of delivered acoustic energy.

102. The system of claim 101, wherein the plurality of optically interacting modes comprises the optically transparent mode, and wherein a portion of the transmitted light energy exits the energy exit port is delivered to the volume.

103. The system of claim 101, wherein the plurality of optically interacting modes comprises the optically absorbing mode and the optically reflective mode, wherein the pattern is opaque and substantially no light energy exits the energy exit port.

104. The system of claim 101, wherein the optically reflective mode comprises a reflective layer mask.

105. The system of claim 101, wherein the optically absorbing mode comprises an absorbing layer mask.

106. The system of claim 101, wherein the pattern comprises a dithering.

107. The system of claim 106, wherein the dithering is a dithered wavelet pattern.

108. The system of claim 101, wherein the pattern spans multiple surfaces.

109. The system of claim 101, wherein the energy exit port is an optical window made of glass, and the light path comprises optical fibre.

110. The system of claim 101, wherein the optically reflective mode comprises a patterned metallic coating deposited using a mask, and the optically absorbing mode comprises a patterned dark coating deposited using a mask.

111. A method, comprising:

receiving a plurality of acoustic return signals, each signal received from a position proximate to an outer surface of a volume in response to delivery of electromagnetic energy to the volume;

applying a pattern detection classifier to each received signal to produce a plurality of classifier output signals, each classifier output signal is representative of an indicator strength as a function of time in each received signal;

reconstructing a spatial representation of the volume from the plurality of classifier output signals; and

,

outputting an image based on the reconstructed spatial representation.

112. The method of claim 111, wherein the indicator strength is tuned to acoustic signals resulting from a pattern on the surface of a probe acoustically coupled to the volume.

113. The method of claim 111, wherein the step of reconstructing a spatial representation comprises using an iterative minimization.