Optical imaging system with direct image construction

• US 20020033454A1
• Filed: 02/06/2001
• Published: 03/21/2002
• Est. Priority Date: 08/04/2000
• Status: Abandoned Application

• Current Assignee: Photonify Technologies Incorporated
• Original Assignee: Photonify Technologies Incorporated
• Inventors: Wang, Ming, Li, Feng, Wang, Lai, Zhou, Shuoming, Cheng, Xuefeng, Hu, Guobao, Xu, Xiaorong
• Application Number:
  US09/778,617
• Publication Number:
  US 20020033454A1
• Time in Patent Office: Days
• US Class Current: 250/339.12
• CPC Class Codes: A61B 2562/0233 Special features of optical sensors or probes classified in A61B5/00
• CPC Class Codes: A61B 2562/0242 for varying or adjusting the optical path length in the tissue
• CPC Class Codes: A61B 2562/043 in a linear array
• CPC Class Codes: A61B 5/14546 for measuring analytes not otherwise provided for, e.g. ions, cytochromes
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: A61B 5/14553 specially adapted for cerebral tissue
• CPC Class Codes: G01N 2021/3144 for oxymetry
• CPC Class Codes: G01N 21/359 using near infrared light
• CPC Class Codes: G01N 21/49 within a body or fluid

Abstract

The invention generally relates to optical imaging systems and methods for providing images of two-dimensional or three-dimensional spatial or temporal distribution of properties of chromophores in a physiological medium. More particularly, the following description provides preferred embodiments of optical imaging systems utilizing efficient, real-time image construction algorithms. A typical optical imaging system includes at least one wave source, at least one wave detector, a movable member, an actuator member, and an imaging member. The wave source emits electromagnetic waves into a target area of the medium, and the wave detector detects electromagnetic waves and generates output signal in response thereto. The movable member includes the wave source and/or detector, and the actuator member moves the movable member along with the wave source and detector over different regions of the target area while the wave detector generates the output signal therefrom. The imaging member generates a set of voxels in the target area and calculates voxel values each of which represents a spatial or temporal average of the property of the chromophore in each voxel. The imaging member generates a set of cross-voxels from the intersecting voxels, and calculates cross-voxel values of the cross-voxels directly from the voxel values of the intersecting voxels. The imaging member then constructs the images of the chromophore properties in the target area. Accordingly, without needing to resort to the time-consuming conventional image reconstruction methods, the optical imaging system of the present invention can construct such images on a substantially real time basis.

Claims

1. An optical imaging system for generating images of a target area of a physiological medium, said images representing distribution of hemoglobins in the medium, comprising:

at least one movable member with one or more wave sources and one or more wave detectors forming a scanning unit which defines at least one of a scanning area and a scanning volume therearound, the member having and which has a longitudinal axis, said wave source(s) configured to irradiate near-infrared electromagnetic waves into said medium and said wave detector(s) configured to detect said near-infrared electromagnetic waves and to generate output signal in response thereto;

an actuator configured to operationally couple with said movable member and to generate at least one movement of said movable member with respect to said target area along at least one curvilinear path; and

an imaging processor configured to receive said output signal, to define therefrom a plurality of voxels in at least a substantial portion of said target area, to determine said hemoglobin property based on the output signal, and to generate said images of said distribution of hemoglobins, wherein each of said voxels has a characteristic dimension and includes a voxel axis along which it extends.

2. The optical imaging system of claim 1 wherein said characteristic dimension of said voxel is one of a height, length, and width thereof and wherein said characteristic dimension is at least one of substantially parallel with, substantially perpendicular to, and arranged to form a pre-selected angle with said curvilinear path of said movable member.

3. The optical imaging system of claim 1 wherein said voxel axis of said voxel is substantially parallel with said longitudinal axis of said scanning unit.

4. The optical imaging system of claim 1 wherein said voxel has a height which is at least substantially similar to a height of said scanning unit.

5. The optical imaging system of claim 1 wherein said voxel direction of said voxels is substantially parallel with said curvilinear path of said movement of said movable member.

6. The optical imaging system of claim 1 wherein said imaging member is configured to sample said output signal at a pre-selected time interval.

7. The optical imaging system of claim 6 wherein said characteristic dimension of said voxel is at least partially proportional to a speed of said movement of said movable member.

8. The optical imaging system of claim 6 wherein said characteristic dimension of said voxel is at least partially proportional to said sampling time interval of said imaging member.

9. The optical imaging system of claim 1 wherein said imaging member is configured to determine a voxel value for each of said voxels and to generate a sequence of said voxel values arranged in an order of said voxels along said voxel direction, each of said voxel values representing an average of at least one of said output signals and said property of said hemoglobins averaged over each of said voxels.

10. The optical imaging system of claim 9 wherein said average is said property averaged over at least one of said scanning area and scanning volume.

11. The optical imaging system of claim 9 wherein said actuator member is configured to generate at least two movements of said movable member along at least two curvilinear paths and wherein said imaging member is configured to define, during each of said movements, a set of said voxels and a sequence of said voxel values corresponding to said set of said voxels.

12. The optical imaging system of claim 11 wherein said imaging member is configured to define at least one set of a plurality of cross-voxels each of which is defined as an intersecting portion of at least two intersecting voxels each belonging to one of said sets of said voxels.

13. The optical imaging system of claim 12 wherein said imaging member is configured to determine a cross-voxel value for each of said cross-voxels and to generate a sequence of cross-voxel values directly from said voxel values of said intersecting voxels.

14. The optical imaging system of claim 13 wherein each of said cross-voxel values is at least one of an arithmetic sum, arithmetic average, geometric sum, geometric average, weighted sum, and weighted average of said voxel values of said intersecting voxels.

15. The optical imaging system of claim 13 wherein each of said cross-voxel values is at least one of an ensemble sum and ensemble average of said voxel values of said intersecting voxels.

16. The optical imaging system of claim 1 wherein said distribution is at least one of two-dimensional distribution and three-dimensional distribution of said property of said hemoglobins.

17. The optical imaging system of claim 1 wherein said distribution represents at least one of spatial distribution and temporal variation of said property of said hemoglobins.

18. The optical imaging system of claim 1 wherein said property is at least one of spatial changes and temporal changes thereof.

19. The optical imaging system of claim 1 wherein said property is at least one of intensive properties of said hemoglobins including concentration thereof, a sum of said concentrations, a difference of said concentrations, a ratio of said concentrations, and a combination thereof.

20. The optical imaging system of claim 1 wherein said property is at least one of extensive properties of said hemoglobins including volume, mass, volumetric flow rate, and mass flow rate thereof.

21. The optical imaging system of claim 20 wherein said property includes at least one of concentration of oxygenated hemoglobin, concentration of deoxygenated hemoglobin, and oxygen saturation defined as a ratio of said concentration of oxygenated hemoglobin to a sum of said concentrations of deoxygenated hemoglobin and oxygenated hemoglobin.

22. The optical imaging system of claim 1 wherein said electromagnetic waves are at least one of sound waves, near-infrared rays, infrared rays, visible lights, ultraviolet rays, lasers, and photons.

24. The optical imaging system of claim 23 wherein said chromophore includes at least one a solvent of said medium, a solute dissolved in said medium, and a substance included in said medium, each of which is configured to interact with said electromagnetic waves irradiated by said wave source and transmitted through said medium.

25. The optical imaging system of claim 23 wherein said chromophore includes at least one of a cytochrome, cytosome, cytosol, enzyme, hormone, neurotransmitter, chemical or chemotransmitter, protein, cholesterol, apoprotein, lipid, carbohydrate, blood cell, water, and hemoglobins including oxygenated and deoxygenated hemoglobin.

27. The optical imaging system of claim 26 wherein each of said voxels has a characteristic dimension, wherein each of said voxels includes a voxel axis along which said voxel extends, and wherein said voxels are sequentially arranged along a curvilinear voxel direction.

28. The optical imaging system of claim 26 wherein said imaging member is configured to determine voxel values for said voxels and to generate a sequence of said voxel values arranged in an order of said voxels along said voxel direction, each of said voxel values representing an average of said property of said hemoglobins averaged over each of said voxels.

29. The optical imaging system of claim 26 wherein said imaging member is configured to define at least one set of a plurality of cross-voxels each of which is defined as an intersecting portion of at least two intersecting voxels each belonging to one of said sets of different voxels and each extending along a different voxel axis.

23. An optical imaging system for generating images of a target area of a physiological medium, said images representing distribution of at least one property of one or more chromophores in said medium, said optical imaging system including at least one wave source configured to irradiate electromagnetic waves into said physiological medium and at least one wave detector configured to detect electromagnetic waves and to generate output signal in response thereto, said optical imaging system comprising:

at least one movable member having at least one of said wave source and at least one of said wave detectors, forming a scanning unit, which defines at least one of a scanning area and a scanning volume therearound and which includes a longitudinal axis connecting said wave source and detector;

an actuator configured to operationally couple with said movable member and to generate at least one movement of said movable member with respect to said target area of said medium along at least one curvilinear path; and

an imaging member configured to receive said output signal, to define a set of a plurality of voxels in at least a substantial portion of said target area, to determine said chromophore property, and to generate said images of said distribution of said chromophore property, wherein each of said voxels has a characteristic dimension and includes a voxel axis along which it extends.

26. An optical imaging system configured to generate images of a target area of a physiological medium, said images representing distribution of hemoglobin property in said medium, said optical imaging system comprising:

at least one sensor assembly including at least one wave source and at least one wave detector, said wave source configured to irradiate near-infrared electromagnetic waves into said medium and said wave detector configured to detect said near-infrared electromagnetic waves and to generate output signal in response thereto;

a body configured to support at least a portion of said sensor assembly;

an actuator member operationally coupling with at least one of said sensor assembly and body and configured to generate at least one movement of at least one of said sensor assembly and body with respect to said target area of said medium along at least one curvilinear path; and

an imaging member configured to receive said output signal, to define a set of a plurality of voxels in at least a substantial portion of said target area, to determine said hemoglobin property by solving a plurality of wave equations applied to said wave source and detector, and to generate said images of said distribution of said hemoglobin property.

30. An optical imaging system for generating images of a target area of a physiological medium, said images representing distribution of at least one property of at least one chromophore in said medium, said optical imaging system including at least one wave source configured to irradiate electromagnetic waves into said physiological medium and at least one wave detector configured to detect electromagnetic waves and to generate output signal in response thereto, said optical imaging system comprising:

at least one portable probe including at least one movable member and an actuator member, wherein said movable member includes at least one of said wave source and detector and wherein said actuator member is configured to operationally couple with said movable member and to generate at least one movement of said movable member along at least one curvilinear path; and

a console including an imaging member configured to receive said output signal, to define a set of a plurality of voxels in said target area, to determine said property of said chromophore by solving a plurality of wave equations applied to said wave source and detector, and to generate said images of said distribution of said chromophore property.

31. An optical imaging system capable of generating images of target areas of a physiological medium wherein said images represent distribution of at least one property of at least one chromophore in said medium, said optical imaging system comprising:

at least one wave source configured to irradiate electromagnetic waves into said target areas of said physiological medium;

at least one wave detector configured to detect electromagnetic waves and to generate output signal in response thereto;

at least one optical probe including at least one movable member in which at least one of said wave source and detector is disposed;

a console operationally coupling with said optical probe and including an imaging member configured to receive said output signal, to define a set of a plurality of voxels in at least substantial portions of said target areas, to determine said chromophore property by solving a plurality of wave equations applied to said wave source and detector, and to generate said images of said distribution of said chromophore property;

an actuator member configured to operationally couple with said movable member and to generate at least one movement of said movable member along at least one curvilinear path; and

a connector member for providing at least one of electrical communication, optical communication, electric power transmission, mechanical power transmission, and data transmission between at least two of said optical probe, console, and actuator member.

32. An optical imaging system capable of generating images of target areas of a physiological medium, said images representing distribution of at least one property of at least one chromophore in said medium, said optical imaging system comprising:

at least two wave sources configured to irradiate electromagnetic waves into said target areas of said medium;

at least two wave detectors configured to generate output signals responsive to electromagnetic waves detected thereby, wherein at least two of said wave sources and at least two of said wave detectors are disposed substantially linearly along a straight line; and

an imaging member configured to receive said output signal, to define a set of a plurality of voxels in at least substantial portions of said target areas, to determine said chromophore property by solving a set of wave equations applied to said wave sources and detectors, and to generate said images of said distribution of said chromophore property.

33. A method for generating images of a target area of a physiological medium by an optical imaging system, said images representing distribution of hemoglobins in said medium, wherein said optical imaging system includes at least one wave source, at least one wave detector, a movable member, and an actuator member, said wave source configured to irradiate near-infrared electromagnetic waves into said target area of said medium, said wave detector configured to detect said near-infrared electromagnetic waves and to generate output signal in response thereto, said movable member configured to include at least one of said wave source and detector, and said actuator member operationally coupling with said movable member, wherein said wave source and detector are configured to define at least one scanning unit having a longitudinal axis connecting said wave source and detector and defining at least one of a scanning area and scanning volume therearound, and wherein said actuator member is configured to generate at least one movement of at least one of said movable member and said scanning unit along at least one curvilinear path, said method comprising the steps of:

placing said movable member on said target area of said medium;

positioning said scanning unit in a first region of said target area;

scanning said first region by irradiating said near-infrared electromagnetic waves thereinto by said wave source and obtaining said output signal therefrom by said wave detector;

manipulating said actuator member to generate said movement in order to move at least one of said movable member and scanning unit from said first region toward another region of said target area of said medium along a first curvilinear path;

defining at least one first set of a plurality of first voxels from said output signal in at least one of said regions of said target area;

determining a first sequence of first voxel values of said first voxels, each first voxel value being a first average of said property averaged over said first voxel; and

generating said images of said distribution of said hemoglobins from said first sequence of said first voxel values.

34. The method of claim 33 further comprising the steps of:

forming optical couplings between said medium and said wave source and detector; and

maintaining said optical couplings during said movement of at least one of said movable member and scanning unit.

35. The method of claim 33 further comprising the steps of:

arranging all of said wave source and detector substantially linearly along a straight line; and

defining said scanning unit having at least one of said scanning area and scanning volume which is less than said target area and target volume, respectively.

36. The method of claim 33 wherein said generating step comprises the step of:

controlling resolution of said images by varying at least one dimension of said first voxels.

37. The method of claim 36 wherein said varying step comprises at least one of the steps of:

adjusting a distance between said wave source and detector;

adjusting geometric arrangement between said wave source and detector;

adjusting at least one of contour, length, and tortuosity of said curvilinear path of said movement of at least one of said movable member and scanning unit;

adjusting a number of said movements of at least one of said movable member and said scanning unit over said target area;

adjusting a speed of said movement of at least one of said movable member and scanning unit; and

adjusting a sampling rate of said output signal.

38. The method of claim 33 further comprising the steps of:

defining at least one second set of a plurality of second voxels in at least one different region of said target area;

determining a second sequence of second voxel values of said second voxels, each second voxel value representing a second average of said property averaged over said second voxel;

defining a first set of a plurality of first cross-voxels each of which is defined as an intersecting portion of at least two intersecting voxels each belonging to a different set of said voxels;

obtaining a first sequence of first cross-voxel values of said first cross-voxels directly from said voxel values of said intersecting voxels; and

generating said images of said distribution of said hemoglobins from said first sequence of said first cross-voxel values.

39. The method of claim 38 wherein said step of obtaining said first sequence of said first cross-voxel values comprises at least one of the steps of:

arithmetically averaging said voxel values of said intersecting voxels;

geometrically averaging said voxel values of said intersecting voxels;

weight-averaging said voxel values of said intersecting voxels; and

ensemble-averaging said voxel values of said intersecting voxels.

40. The method of claim 38 further comprising the steps of:

defining at least one third set of a plurality of third voxels in at least one yet different region of said target area;

determining a third sequence of third voxel values of said third voxels, each third voxel value being a third average of said property averaged over said third voxel;

defining a second set of a plurality of second cross-voxels each defined as an intersecting portion of at least two intersecting voxels each belonging to a different set of said voxels;

obtaining a second sequence of second cross-voxel values of said second cross-voxel directly from said voxel values of said intersecting voxels; and

generating said images of said distribution of said hemoglobins from said second sequence of said second sequence of said second cross-voxel values.

41. The method of claim 40 further comprising the step of:

generating said images of said distribution of said hemoglobins by arranging a plurality of said sequences of said cross-voxel values, thereby improving the resolution of said images.

42. A method for generating images of a target area of a physiological medium by an optical imaging system, said images representing distribution of at least one property of at least one chromophore in said medium, wherein said optical imaging system includes at least one wave source configured to irradiate electromagnetic waves into said medium and at least one wave detector configured to detect electromagnetic waves and to generate output signal in response thereto, said method comprising the steps of:

positioning said wave source and detector in said target area;

defining a first set of first voxels from said output signals;

determining a first sequence of first voxel values of said first voxels, each first voxel value representing a first average of said property averaged over said first voxel;

defining a second set of second voxels from said output signals;

determining a second sequence of second voxel values of said second voxels, each second voxel value representing a second average of said property averaged over said second voxel;

constructing a first set of first cross-voxels each defined as an intersecting portion of at least two intersecting voxels each of which belongs to one of said first and second sets of said first and second voxels, respectively;

calculating a first sequence of first cross-voxel values of said first cross-voxels directly from said voxel values of said intersecting voxels; and

generating said images of said distribution of said chromophore property from said first sequence of said first cross-voxel values.

43. The method of claim 42 wherein at least one of said defining steps comprises the step of defining said set of said voxels per at least one of:

each pre-selected distance along said target area;

each pre-selected sampling interval of said output signal;

each pair of one of said wave sources and one of said wave detectors; and

each scanning unit comprising at least two of said wave sources and at least two of said wave detectors.

44. The method of claim 42 wherein at least one of said defining steps comprises the step of:

adjusting resolution of said images of said distribution of said property by varying at least one dimension of at least one of said voxels and cross-voxels.

45. The method of claim 42 wherein at least one of said determining steps comprises at least one of the steps of:

averaging said property over an area of said voxel; and

averaging said property over a volume of said voxel.

46. The method of claim 42 wherein said calculating step comprises at least one of the steps of:

arithmetically averaging said voxel values of said intersecting voxels;

geometrically averaging said voxel values of said intersecting voxels;

weight-averaging said voxel values of said intersecting voxels; and

ensemble-averaging said voxel values of said intersecting voxels.

47. A method for generating images of a target area of a physiological medium by an optical imaging system, said images representing distribution of at least one property of at least one chromophore in said medium, wherein said optical imaging system includes at least one wave source, at least one wave detector, a movable member, and an actuator member, said wave source configured to irradiate electromagnetic waves into said medium, said wave detector configured to generate output signal in response to said electromagnetic waves detected thereby, said movable member configured to include at least one of said wave source and detector, and said actuator member operationally coupling with said movable member, wherein said wave source and detector are configured to form a movable scanning unit which includes a longitudinal axis connecting said wave source and detector and which defines at least one of a scanning area and scanning volume therearound, and wherein said actuator member is configured to generate at least one movement of at least one of said movable member and scanning unit along at least one curvilinear path, said method comprising the steps of:

placing said movable member on said target area of said medium;

positioning said scanning unit in a first region of said target area;

manipulating said actuator member to generate a first movement of at least one of said movable member and scanning unit from said first region to a second region of said target area along a first curvilinear path;

defining a first set of first voxels from said output signals in at least a portion of said target area;

determining a first sequence of first voxel values of said first voxels, each first voxel value representing a first average of said property averaged over said first voxel;

defining a second set of second voxels from said output signals in at least a portion of said target area;

determining a second sequence of second voxel values of said second voxels, each second voxel value representing a second average of said property averaged over said second voxel;

constructing a set of cross-voxels each of which is defined as an intersecting portion of at least two intersecting voxels each of which belongs to one of said first and second sets of said first and second voxels, respectively;

calculating a sequence of cross-voxel values of said cross-voxels directly from said voxel values of said intersecting voxels; and

generating said images of said distribution of said property directly from said sequence of said cross-voxel values.