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 system for in-operating-theatre imaging of fresh tissue samples resected during surgery for pathology assessment, the system comprising:
a light source for providing an illumination beam that illuminates a fluorescent stained, fresh sample, wherein the fresh sample is held by a sample holder located in an operating theatre;
a beam expander for expanding a waist of the illumination beam to a size comparable to a field of view to be illuminated, thereby providing a collimated illumination beam;
a beam splitter located between the sample and a detector array, for directing the collimated illumination beam toward a micro optical element array;
the micro optical element array comprising a plurality of micro optical elements, wherein each micro optical element of the micro optical element array:
(i) collects a first portion of the collimated illumination beam and focuses an entirety of that portion onto a single focal point, thereby forming a focal plane comprising an array of tight foci for exciting fluorescence in the sample to produce back-emitted light, and
(ii) collects back-emitted light from the sample, and the collected back-emitted light propagates and is directed to the detector array;
a transparent window onto which the sample is placed for imaging, wherein a gap of less than 500 μm is maintained between the micro optical element array and the transparent window, and wherein the focal plane is located at a distance from 10 μm to 200 μm above the transparent window;
a high precision scanning stage for laterally moving a position of the micro optical element array relative to the transparent window and the detector array along a scan pattern during a single scan such that back-emitted light collected by the micro optical element array is detected by the detector array to form a scanned confocal image corresponding to an area scanned by the scan pattern during the single scan wherein:
a 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;
an aperture stop for spatially filtering the back-emitted light collected by the micro optical element array, thereby rejecting out-of-focus light;
the detector array, wherein the detector array comprises a plurality of detectors, each detector independently detecting a portion of the back-emitted light collected by a micro optical element in the micro optical element array; and
a computing device comprising a processor and a memory storing instructions thereon that, when executed by the processor, cause the processor to construct an image representing an optical slice of the fresh tissue sample based on the back-emitted light detected by the detector array.
2. The system of claim 1 , wherein the memory stores instructions thereon that, when executed by the processor, cause the processor to send, 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 system of claim 1 , wherein each micro optical element of the micro optical element array has a curved surface facing the sample.
4. The system of claim 1 , wherein each micro optical element of the micro optical element array has a curved surface facing the collimated illumination beam.
5. The system of claim 3 , wherein the curved surface of each micro optical element has a conical shaped surface.
6. The system of claim 5 , wherein the curved surface of each micro optical element has a hyperbolic shaped surface.
7. The system of claim 5 , wherein the curved surface of each micro optical element has a conic constant from −1.8 to −2.2.
8. The system of claim 1 , wherein each micro optical element in the micro optical element array has a spot size from 0.2 μm to 5 μm.
9. The system of claim 1 , wherein a free working distance is from 80 μm to 450 μm.
10. The system of claim 1 , comprising a kinematic support structure having at least three feet of adjustable height, the support structure supporting the scanning stage such that the height and tilt of the transparent window relative to the micro optical element array and the corresponding optical path are adjustable.
11. The system of claim 1 , comprising:
a first flat mirror for reflecting the collimated illumination beam onto the beam splitter.
12. The system of claim 11 , comprising:
a second flat mirror for reflecting the collimated illumination beam from the beam splitter to the micro optical element array.
13. The system of claim 12 , wherein the second flat mirror reflects the back-emitted light passed through the micro optical element array from the sample through the beam splitter.
14. The system of claim 1 , comprising:
a field lens for focusing the back-emitted light prior to spatially filtering the back-emitted light.
15. The system of claim 1 , wherein the beam expander is a collimating lens.
16. The system of claim 1 , wherein the ratio of micro optical elements to detectors is from 1:1 to 1:100.
17. The system of claim 1 , wherein the micro optical element array comprises from 1000 to 100,000 micro optical elements.
18. The system of claim 1 , wherein the micro optical element array comprises one or more intermediate areas, wherein each of the one or more intermediate areas is located in between a first micro optical element of the micro optical element array and a second micro optical element of the micro optical element array, wherein the one or more intermediate areas is coated with a non-transmissive material that substantially prevents at least one of: (i) transmission of the collimated illumination beam through the intermediate area to the sample, and (ii) transmission of back-emitted light through the intermediate area to the detector array.
19. The system of claim 1 , wherein the instructions cause the processor to construct a single scanned confocal image representing the optical slice of the fresh tissue sample based on the back-emitted light detected by the detector array.
20. The system of claim 1 , wherein the transparent window is exposed thereby providing a surface onto which to the sample may be directly positioned, and wherein the micro optical elements of the micro optical element array focus onto a focal plane that is located 10 μm to 200 μm above the transparent window such that the focal plane resides within the sample when the sample is positioned directly on the exposed transparent window.
21. The system of claim 1 , comprising a disposable transparent film placed on the transparent window,
wherein the disposable transparent film provides a surface onto which the sample may be directly positioned for imaging and wherein the micro optical elements of the micro optical element array focus onto the focal plane that is located 10 μm to 200 μm above the transparent window such that the focal plane resides within the sample when the sample is positioned directly on the disposable transparent film, and
wherein the disposable transparent film prevents direct contact of the sample with the rest of the system.
22. The system of claim 1 , wherein the scanning stage is a three axis positioning stage with precision equal to or better than one micrometer.