Method and system for near-infrared fluorescence contrast-enhanced imaging with area illumination and area detection

1. A method of imaging, comprising:

directing time-varying excitation light at a surface area of a tissue, the tissue comprising a fluorescent target;

modulating the intensity of the excitation light at a radio frequency;

detecting, substantially at a two-dimensional sensor surface, time-varying emission light from the fluorescent target in response to the time-varying excitation light stimulating the fluorescent target;

filtering the time-varying emission light to reject excitation light re-emitted from the material;

determining a spatial distribution of amplitude and phase-delay of the detected time-varying emission light;

detecting time-varying excitation light specularly-reflected by the fluorescent target;

determining a spatial distribution of amplitude and phase-delay of the time-varying excitation light incident on the surface area based on the reflected time-varying excitation light; and

generating a three-dimensional image of the fluorescent target based on the spatial distributions of the incident time-varying excitation light and the time-varying emission light.

2. A method of imaging, comprising:

directing time-varying excitation light at a surface area of a light scattering material, the material comprising a fluorescent target;

detecting, substantially at a two-dimensional sensor surface, time-varying emission light from the fluorescent target in response to the time-varying excitation light stimulating the fluorescent target;

filtering the time-varying emission light to reject excitation light re-emitted from the material; and

generating a three-dimensional image of the fluorescent target based on the detection substantially at the sensor surface.

3. The method of claim 2 , wherein the fluorescent agent comprises indocyanine green (“ICG”).

4. The method of claim 2 , wherein the surface area is greater than 1 millimeter squared (mm 2 ).

5. The method of claim 2 , further comprising determining a spatial distribution of amplitude and phase-delay of the detected time-varying emission light.

6. The method of claim 5 , further comprising:

detecting time-varying excitation light specularly-reflected by the fluorescent target; and

determining a spatial distribution of amplitude and phase-delay of the time-varying excitation light incident on the surface area based on the reflected time-varying excitation light.

7. The method of claim 6 , wherein the three dimensional image of the fluorescent target is based on the spatial distributions of the incident time-varying excitation light and the time-varying emission light.

8. The method of claim 2 , wherein the time-varying excitation light comprises a planar wave.

9. The method of claim 2 , wherein the material comprises tissue.

10. The method of claim 2 , further comprising modulating the intensity of the excitation light at a radio frequency.

11. The method of claim 6 , wherein detecting time-varying excitation light specularly-reflected by the fluorescent target comprises:

detecting excitation light emitted from the light scattering material;

detecting multiply-scattered excitation light emitted from the light scattering material; and

subtracting the detected multiply-scattered excitation light from the detected excitation light emitted from the light scattering material to determine the specularly-reflected excitation light.

12. The method of claim 2 , wherein the two-dimensional sensor surface area is approximately 16 cm 2 .

13. A system for imaging, comprising:

a laser diode operable to direct time-varying excitation light at a surface area of a light scattering material, the material comprising a fluorescent target;

an image intensifier operable to detecting, substantially at a two-dimensional sensor surface, time-varying emission light from the fluorescent target in response to the time-varying excitation light stimulating the fluorescent target;

one or more optical filters operable to filter the time-varying emission light to reject excitation light re-emitted from the material; and

an imaging apparatus operable to generate a three-dimensional image of the fluorescent target based on the detection substantially at the sensor surface.

14. The system of claim 13 , wherein the fluorescent agent comprises indocyanine green (“ICG”).

15. The system of claim 13 , wherein the surface area is approximately 9 centimeters squared (cm 2 ).

16. The system of claim 13 , the imaging apparatus further operable to determine a spatial distribution of amplitude and phase-delay of the detected time-varying emission light.

17. The system of claim 13 , further comprising a plurality of linear polarizers operable to pass reflected excitation light in a first configuration and multiply-reflected excitation light in a second configuration; and the image apparatus further operable to determine a spatial distribution of amplitude and phase-delay of the time-varying excitation light incident on the surface area based on the reflected and multiply-reflected excitation light.

18. The system of claim 17 , wherein the three dimensional image of the fluorescent target is based on the spatial distributions of the incident time-varying excitation light and the time-varying emission light.

19. The system of claim 13 , wherein the time-varying excitation light comprises a planar wave.

20. The system of claim 13 , wherein the material comprises tissue.

21. The system of claim 13 , wherein an intensity of the time-varying excitation light is modulated at a radio frequency.