Systems and methods for in-operating-theatre imaging of fresh tissue resected during surgery for pathology assessment
The disclosed technology brings histopathology into the operating theater, to enable real-time intra-operative digital pathology. The disclosed technology utilizes confocal imaging devices image, in the operating theater, “optical slices” of fresh tissue—without the need to physically slice and otherwise process the resected tissue as required by frozen section analysis (FSA). The disclosed technology, in certain embodiments, includes a simple, operating-table-side digital histology scanner, with the capability of rapidly scanning all outer margins of a tissue sample (e.g., resection lump, removed tissue mass). Using point-scanning microscopy technology, the disclosed technology, in certain embodiments, precisely scans a thin “optical section” of the resected tissue, and sends the digital image to a pathologist rather than the real tissue, thereby providing the pathologist with the opportunity to analyze the tissue intra-operatively. Thus, the disclosed technology provides digital images with similar information content as FSA, but faster and without destroying the tissue sample itself.
1. A method for in-operating-theatre imaging of fresh tissue samples resected during surgery for pathology assessment, the method comprising:
providing, by a light source, an illumination beam for illuminating a fluorescent stained, fresh sample held by a sample holder located in an operating theatre;
directing a collimated light beam via illumination optics onto the fresh sample held by the sample holder in the operating theatre, wherein the illumination optics comprise:
a beam expander expanding a waist of the illumination beam, thereby providing the collimated illumination beam,
a beam splitter, located between the sample and a detector array, directing the collimated illumination beam toward a micro optical element array, and
the micro optical element array for focusing the collimated illumination beam from the beam splitter onto the sample, thereby forming an array of tight foci for exciting the fluorescence in the sample to produce the back-emitted light, wherein:
each micro optical element focuses a portion of the collimated illumination beam onto the sample, and
a gap of less than 500 μm is maintained between the micro optical element array and a transparent window onto which the sample is placed for imaging;
directing the back-emitted light from the sample to the detector array via detecting optics, the detecting optics comprising:
the micro optical element array, which collects the back-emitted light from the sample, which propagates and is directed to the detector array, and
an aperture stop spatially filtering the back-emitted light, thereby rejecting out-of-focus light;
moving, by a scanning stage, a position of the micro optical element array relative to the transparent window and the detector array such that back-emitted light focused by the micro optical element array is detected by the detector array to form a scanned confocal image, wherein:
the position of the transparent window relative to the detector array is fixed, and
the scanning stage and micro optical element array are confined within the system such that the scanning stage and micro optical element array are protected from the sample by the transparent window;
detecting, by the detector array, the back-emitted light filtered by the aperture stop, wherein the detector array comprises a plurality of detectors, each detector independently detecting a portion of the back-emitted light originating from a micro optical element in the micro optical element array; and
constructing, by a processor of a computing device, an image representing an optical slice of the fresh tissue sample based on the back-emitted light detected by the detector array.
2. The method of claim 1 , comprising:
sending, by the processor, via a network, the image to a second computing device such that a pathologist in a remote location can perform the pathology assessment.
3. The method of claim 1 , wherein the micro optical element array comprises a plurality of micro optical elements having curved surfaces facing the sample.
4. The method of claim 1 , wherein the micro optical element array comprises a plurality of micro optical elements having curved surfaces facing the collimated illumination beam.
5. The method of claim 1 , wherein the curved surface of each micro optical element has a conical shaped surface.
6. The method of claim 5 , wherein the curved surface of each micro optical element has a hyperbolic shaped surface.
7. The method of claim 5 , wherein the curved surface of each micro optical element has a conic constant from −1.8 to −2.2.
8. The method of claim 1 , wherein each micro optical element has a Strehl ratio greater than or equal to 0.8.
9. The method of claim 1 , wherein each micro optical element has a spot size of 0.1 μm to 2 μm.
10. The method of claim 1 , wherein a free working distance is from 80 μm to 450 μm.
11. The method of claim 1 , wherein the micro optical element array has a focal plane from 10 μm to 200 μm above the transparent window.
12. The method of claim 1 , wherein a kinematic support structure having at least three feet of adjustable height supports the scanning stage such that the height and tilt of the transparent window relative to the micro optical element array are adjustable.
13. The method of claim 1 , wherein the illumination optics comprises:
a first flat mirror reflecting the collimated illumination beam onto the beam splitter.
14. The method of claim 13 , wherein the illumination optics comprises:
a second flat mirror reflecting the collimated illumination beam from the beam splitter to the micro optical element array.
15. The method of claim 14 , wherein the second flat mirror reflects the back-emitted light passed through the micro optical element array from the sample through the beam splitter.
16. The method of claim 1 , wherein the detection optics comprises:
a field lens focusing the back-emitted light prior to spatially filtering the back-emitted light.
17. The method of claim 1 , wherein the beam expander is a collimating lens.
18. The method of claim 1 , wherein the ratio of detectors to micro optical elements is from 1:1 to 1:100.
19. The method of claim 1 , wherein the micro optical element array comprises from 1000 to 100,000 micro optical elements.