Fiber-bundle microendoscopy with sub-diffuse reflectance spectroscopy and intensity mapping for multimodal optical biopsy of stratified epithelium

Abstract

Early detection of structural or functional changes in dysplastic epithelia may be crucial for improving long-term patient care. Recent work has explored myriad non-invasive or minimally invasive "optical biopsy" techniques for diagnosing early dysplasia, such as high-resolution microendoscopy, a method to resolve sub-cellular features of apical epithelia, as well as broadband sub-diffuse reflectance spectroscopy, a method that evaluates bulk health of a small volume of tissue. We present a multimodal fiber-based microendoscopy technique that combines highresolution microendoscopy, broadband (450-750 nm) sub-diffuse reflectance spectroscopy (sDRS) at two discrete source-detector separations (374 and 730 μm), and sub-diffuse reflectance intensity mapping (sDRIM) using a 635 nm laser. Spatial resolution, magnification, field-of-view, and sampling frequency were determined. Additionally, the ability of the sDRS modality to extract optical properties over a range of depths is reported. Following this, proof-of-concept experiments were performed on tissuesimulating phantoms made with poly(dimethysiloxane) as a substrate material with cultured MDA-MB-468 cells. Then, all modalities were demonstrated on a human melanocytic nevus from a healthy volunteer and on resected colonic tissue from a murine model. Qualitative in vivo image data is correlated with reduced scattering and absorption coefficients. References and links 1. P. Sharma and E. Montgomery, "Gastrointestinal dysplasia," Pathology 45(3), 273-285 (2013). 2. P. M. Speight, "Update on oral epithelial dysplasia and progression to cancer," Head Neck Pathol. 1(1), 61-66 (2007). 3. Y. Zhang, "Epidemiology of esophageal cancer," World J. Gastroenterol. 19(34), 5598-5606 (2013). 4. N. Harpaz and A. D. Polydorides, "Colorectal dysplasia in chronic inflammatory bowel disease: pathology, clinical implications, and pathogenesis," Arch. Pathol. Lab. Med. 134(6), 876-895 (2010). 5. M. Ponz de Leon and C. Di Gregorio, "Pathology of colorectal cancer," Dig. Liver Dis. 33(4), 372-388 (2001). 6. M. J. Arends, C. H. Buckley, and M. Wells, "Aetiology, pathogenesis, and pathology of cervical neoplasia," J.Clin. Pathol. 51(2), 96-103 (1998 170-173 (2005). 11. M. Gu, H. Bao, and H. Kang, "Fibre-optical microendoscopy," J. Microsc. 254(1), 13-18 (2014) properties of pigmented skin lesions including melanoma using oblique incidence diffuse reflectance spectrometry," J.

Diffuse optical microscopy for quantification of depth-dependent epithelial backscattering in the cervix

“…20 Most cancers originate from epithelium, and, therefore, early detection of cancer by optical means must focus on the optical properties of superficial tissue layers. [23][24][25][26][27][28][29][30][31][32][33] Surface sensitivity can be obtained through polarization gated spectroscopy, 23 or single-and multifiber reflectance spectroscopy [24][25][26][27][28][29][30] including differential path length spectroscopy. 31 As a nondiffuse optical imaging modality, optical coherence tomography features high epithelial contrast 33 and represents another well-suited yet more expensive means for the detection of tissue microstructure.…”

In vivo measurement of non-keratinized squamous epithelium using a spectroscopic microendoscope with multiple source-detector separations

“…The fluorescent signal passes through the 475 nm dichroic mirror, reflects off a 590 nm dichroic mirror, and passes through a 525/40 nm bandpass filter and 50 mm tube lens into a CMOS camera to project an image of fluorescently stained tissue on a monitor. This imaging modality has been described previously [5]. …”

“…To do this, we have designed a multimodal imaging and spectroscopy microendoscope with multiple source-detector separations. This microendoscope employs two modalities within a single, fiber-bundle probe: high-resolution microendoscopy and broadband sub-diffuse reflectance spectroscopy (sDRS) [5]. The high-resolution microendoscopy modality is a well-characterized imaging modality than can image fluorescently labeled, apical cell nuclei within a small field-of-view, typically around 1 mm in diameter [5–12].…”

“…This microendoscope employs two modalities within a single, fiber-bundle probe: high-resolution microendoscopy and broadband sub-diffuse reflectance spectroscopy (sDRS) [5]. The high-resolution microendoscopy modality is a well-characterized imaging modality than can image fluorescently labeled, apical cell nuclei within a small field-of-view, typically around 1 mm in diameter [5–12]. The benefit of this modality is the ability to non-invasively monitor the apical epithelial tissue environment and quantify parameters such as nuclear-cytoplasmic ratio or cells-per-area, which could elucidate changes associated with dysplasia.…”

“…Therefore, we employ a broadband sDRS modality that has the potential to provide clinically relevant quantitative information at various thicknesses within the epithelium and underlying connective tissue. Clinically relevant quantitative information includes tissue hemoglobin concentration and bulk tissue oxygen saturation, and other optical properties, including reduced scattering coefficient (μ s ′), absorption coefficient (μ a ), can be quantified as well [5, 13–19]. …”