Three-dimensional virtual histology in unprocessed resected tissues with photoacoustic remote sensing (PARS) microscopy and optical coherence tomography (OCT)

Abstract

Histological images are critical in the diagnosis and treatment of cancers. Unfortunately, current methods for capturing these microscopy images require resource intensive tissue preparation that may delay diagnosis for days or weeks. To streamline this process, clinicians are limited to assessing small macroscopically representative subsets of tissues. Here, a combined photoacoustic remote sensing (PARS) microscope and swept source optical coherence tomography system designed to circumvent these diagnostic limitations is presented. The proposed multimodal microscope provides label-free three-dimensional depth resolved virtual histology visualizations, capturing nuclear and extranuclear tissue morphology directly on thick unprocessed specimens. The capabilities of the proposed method are demonstrated directly in unprocessed formalin fixed resected tissues. The first images of nuclear contrast in resected human tissues, and the first three-dimensional visualization of subsurface nuclear morphology in resected Rattus tissues, captured with a non-contact photoacoustic system are presented here. Moreover, the proposed system captures the first co-registered OCT and PARS images enabling direct histological assessment of unprocessed tissues. This work represents a vital step towards the development of a rapid histological imaging modality to circumvent the limitations of current histopathology techniques.

Interpreting microscopic structures in virtually stained histological sections for veterinary oncology applications

“…Considering the training data preparation, required for the supervised learning framework implementation, such approach allowed us pixel registration matching between the fluorescence input images and the corresponding brightfield H&E images. In this sense, our used strategy is slightly different from samples preparation workflow reported in 5,12,34,35 permitting avoidance of the sample handling process that involves measurement of the unstained slide first, staining the same slide with H&E, coversliping it and measuring it once more, in order to get a match between the VS tissue structure and stained with H&E. Instead, we used an unpaired image to image translation (refered as to stage 4) . Results of stage 4 VS, using unstained deparaffinized section of a soft tissue sarcoma from a cat onto which transfer learning protocol was applied, produced VS images that partially resembled H&E stained section but had suboptimal contrast between red and blue colors and were blurry.…”

OCT-Guided Surgery for Gliomas: Current Concept and Future Perspectives

“…According to these possible implementations, several OCT scanner designs have been investigated ( Figure 1 ): handheld imaging probes [ 22 , 23 , 24 , 36 ], surgical instrumentation (e.g., biopsy needle) [ 9 , 10 , 11 ], microscope-integrated systems [ 20 , 43 , 44 ] and non-portable stationary OCT systems [ 25 , 45 , 46 ] that can be used in histopathological studies as a part of hybrid optical imaging systems providing label-free histology [ 47 ]. Considering multifunctionality of OCT in neurosurgery, the multipurpose device with a particular set of OCT probes could be preferred.…”

Virtual histological staining of label-free total absorption photoacoustic remote sensing (TA-PARS)

“…Over the past few years, PARS has emerged as a powerful contender in the label-free histological imaging space 34 – 36 , 38 . PARS may emulate current histochemical staining, by targeting the UV absorption of DNA (analogous to hematoxylin staining) 34 , 35 , and by targeting the 420 nm absorption of cytochromes (analogous to hematoxylin staining) 34 . Recent works have shown that PARS may offer high contrast and high spatial resolution in freshly resected tissue, formalin fixed tissue, and FFPE tissue sections 35 , 36 .…”

“…PARS may emulate current histochemical staining, by targeting the UV absorption of DNA (analogous to hematoxylin staining) 34 , 35 , and by targeting the 420 nm absorption of cytochromes (analogous to hematoxylin staining) 34 . Recent works have shown that PARS may offer high contrast and high spatial resolution in freshly resected tissue, formalin fixed tissue, and FFPE tissue sections 35 , 36 . In resected tissues, PARS has even been shown to provide 3D imaging of subsurface nuclei 35 .…”

“…Recent works have shown that PARS may offer high contrast and high spatial resolution in freshly resected tissue, formalin fixed tissue, and FFPE tissue sections 35 , 36 . In resected tissues, PARS has even been shown to provide 3D imaging of subsurface nuclei 35 .…”