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Dey R, Alexandrov S, Owens P, Kelly J, Phelan S, Leahy M. Skin cancer margin detection using nanosensitive optical coherence tomography and a comparative study with confocal microscopy. BIOMEDICAL OPTICS EXPRESS 2022; 13:5654-5666. [PMID: 36733740 PMCID: PMC9872867 DOI: 10.1364/boe.474334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 09/23/2022] [Accepted: 09/26/2022] [Indexed: 05/08/2023]
Abstract
Excision biopsy and histology represent the gold standard for morphological investigation of the skin, in particular for cancer diagnostics. Nevertheless, a biopsy may alter the original morphology, usually requires several weeks for results, is non-repeatable on the same site and always requires an iatrogenic trauma. Hence, diagnosis and clinical management of diseases may be substantially improved by new non-invasive imaging techniques. Optical Coherence Tomography (OCT) is a non-invasive depth-resolved optical imaging modality based on low coherence interferometry that enables high-resolution, cross-sectional imaging in biological tissues and it can be used to obtain both structural and functional information. Beyond the resolution limit, it is not possible to detect structural and functional information using conventional OCT. In this paper, we present a recently developed technique, nanosensitive OCT (nsOCT), improved using broadband supercontinuum laser, and demonstrate nanoscale sensitivity to structural changes within ex vivo human skin tissue. The extended spectral bandwidth permitted access to a wider distribution of spatial frequencies and improved the dynamic range of the nsOCT. Firstly, we demonstrate numerical and experimental detection of a few nanometers structural difference using the nsOCT method from single B-scan images of phantoms with sub-micron periodic structures, acting like Bragg gratings, along the depth. Secondly, our study shows that nsOCT can distinguish nanoscale structural changes at the skin cancer margin from the healthy region in en face images at clinically relevant depths. Finally, we compare the nsOCT en face image with a high-resolution confocal microscopy image to confirm the structural differences between the healthy and lesional/cancerous regions, allowing the detection of the skin cancer margin.
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Affiliation(s)
- Rajib Dey
- Tissue Optics and Microcirculation Imaging (TOMI) Facility, National Biophotonics and Imaging Platform School of Physics, National University of Ireland, Galway, Galway, Ireland
| | - Sergey Alexandrov
- Tissue Optics and Microcirculation Imaging (TOMI) Facility, National Biophotonics and Imaging Platform School of Physics, National University of Ireland, Galway, Galway, Ireland
| | - Peter Owens
- Center for Microscopy and Imaging, National University of Ireland, Galway, Galway, Ireland
| | - Jack Kelly
- Plastic and Reconstructive Surgery, Galway University Hospital, Galway, Ireland
| | - Sine Phelan
- Department of Anatomic Pathology, Galway University Hospital and Department of Pathology, National University of Ireland, Galway, Galway, Ireland
| | - Martin Leahy
- Tissue Optics and Microcirculation Imaging (TOMI) Facility, National Biophotonics and Imaging Platform School of Physics, National University of Ireland, Galway, Galway, Ireland
- Institute of Photonic Sciences (ICFO), Barcelona, Spain
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Alexandrov S, Arangath A, Zhou Y, Murphy M, Duffy N, Neuhaus K, Shaw G, McAuley R, Leahy M. Accessing depth-resolved high spatial frequency content from the optical coherence tomography signal. Sci Rep 2021; 11:17123. [PMID: 34429483 PMCID: PMC8385072 DOI: 10.1038/s41598-021-96619-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2020] [Accepted: 07/28/2021] [Indexed: 11/17/2022] Open
Abstract
Optical coherence tomography (OCT) is a rapidly evolving technology with a broad range of applications, including biomedical imaging and diagnosis. Conventional intensity-based OCT provides depth-resolved imaging with a typical resolution and sensitivity to structural alterations of about 5–10 microns. It would be desirable for functional biological imaging to detect smaller features in tissues due to the nature of pathological processes. In this article, we perform the analysis of the spatial frequency content of the OCT signal based on scattering theory. We demonstrate that the OCT signal, even at limited spectral bandwidth, contains information about high spatial frequencies present in the object which relates to the small, sub-wavelength size structures. Experimental single frame imaging of phantoms with well-known sub-micron internal structures confirms the theory. Examples of visualization of the nanoscale structural changes within mesenchymal stem cells (MSC), which are invisible using conventional OCT, are also shown. Presented results provide a theoretical and experimental basis for the extraction of high spatial frequency information to substantially improve the sensitivity of OCT to structural alterations at clinically relevant depths.
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Affiliation(s)
- Sergey Alexandrov
- National University of Ireland, National Biophotonics and Imaging Platform, School of Physics, Tissue Optics and Microcirculation Imaging Group, Galway, H91 TK33, Ireland.
| | - Anand Arangath
- National University of Ireland, National Biophotonics and Imaging Platform, School of Physics, Tissue Optics and Microcirculation Imaging Group, Galway, H91 TK33, Ireland
| | - Yi Zhou
- National University of Ireland, National Biophotonics and Imaging Platform, School of Physics, Tissue Optics and Microcirculation Imaging Group, Galway, H91 TK33, Ireland
| | - Mary Murphy
- Regenerative Medicine Institute, School of Medicine, National University of Ireland, Galway, Ireland
| | - Niamh Duffy
- Regenerative Medicine Institute, School of Medicine, National University of Ireland, Galway, Ireland
| | - Kai Neuhaus
- National University of Ireland, National Biophotonics and Imaging Platform, School of Physics, Tissue Optics and Microcirculation Imaging Group, Galway, H91 TK33, Ireland
| | - Georgina Shaw
- Regenerative Medicine Institute, School of Medicine, National University of Ireland, Galway, Ireland
| | - Ryan McAuley
- National University of Ireland, National Biophotonics and Imaging Platform, School of Physics, Tissue Optics and Microcirculation Imaging Group, Galway, H91 TK33, Ireland
| | - Martin Leahy
- National University of Ireland, National Biophotonics and Imaging Platform, School of Physics, Tissue Optics and Microcirculation Imaging Group, Galway, H91 TK33, Ireland.,Institute of Photonic Sciences (ICFO), Barcelona, Spain
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Alexandrov S, McGrath J, Sheppard CJR, Boccafoschi F, Giannini C, Sibillano T, Subhash H, Hogan J, Leahy M. Label-free ultra-sensitive visualization of structure below the diffraction resolution limit. JOURNAL OF BIOPHOTONICS 2018; 11:e201700385. [PMID: 29570942 DOI: 10.1002/jbio.201700385] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Accepted: 03/19/2018] [Indexed: 05/24/2023]
Abstract
For both fundamental study of biological processes and early diagnosis of diseases, information about nanoscale changes in tissue and cell structure is crucial. Nowadays, almost all currently known nanoscopy methods rely upon the contrast created by fluorescent stains attached to the object or molecule of interest. This causes limitations due to the impact of the label on the object and its environment, as well as its applicability in vivo, particularly in humans. In this paper, a new label-free approach to visualize small structure with nano-sensitivity to structural alterations is introduced. Numerically synthesized profiles of the axial spatial frequencies are used to probe the structure within areas whose size can be beyond the diffraction resolution limit. Thereafter, nanoscale structural alterations within such areas can be visualized and objects, including biological ones, can be investigated with sub-wavelength resolution, in vivo, in their natural environment. Some preliminary results, including numerical simulations and experiments, which demonstrate the nano-sensitivity and super-resolution ability of our approach, are presented.
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Affiliation(s)
- Sergey Alexandrov
- Tissue Optics & Microcirculation Imaging Group, School of Physics, National University of Ireland, Galway, Ireland
| | - James McGrath
- Tissue Optics & Microcirculation Imaging Group, School of Physics, National University of Ireland, Galway, Ireland
| | - Colin J R Sheppard
- Department of Nanophysics, Istituto Italiano di Tecnologia, Genoa, Italy
| | - Francesca Boccafoschi
- Department of Health Sciences, University of Piemonte Orientale "A. Avogadro", Novara, Italy
| | - Cinzia Giannini
- Institute of Crystallography, National Research Council, Bari, Italy
| | - Teresa Sibillano
- Institute of Crystallography, National Research Council, Bari, Italy
| | - Hrebesh Subhash
- Colgate-Palmolive Global Technology Center, Piscataway, New Jersey
| | - Josh Hogan
- Compact Imaging, Mountain View, California
| | - Martin Leahy
- Tissue Optics & Microcirculation Imaging Group, School of Physics, National University of Ireland, Galway, Ireland
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Dsouza R, Won J, Monroy GL, Hill MC, Porter RG, Novak MA, Boppart SA. In vivo detection of nanometer-scale structural changes of the human tympanic membrane in otitis media. Sci Rep 2018; 8:8777. [PMID: 29884809 PMCID: PMC5993811 DOI: 10.1038/s41598-018-26514-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 05/11/2018] [Indexed: 01/25/2023] Open
Abstract
Otitis media (OM) is a common ear infection and a leading cause of conductive hearing loss in the pediatric population. Current technologies such as otoscopy, pneumatic otoscopy, tympanometry, and acoustic reflectometry are used to diagnose OM, which can reasonably diagnose the infection with a sensitivity and specificity of 50-90% and 60-90%, respectively. However, these techniques provide limited information about the physical architecture of the tympanic membrane (TM), or what may lie behind it. Here, we report the detection of nanometer-scale structural changes of the TM using nano-sensitive optical coherence tomography (nsOCT). In total, an image dataset from 65 pediatric subjects from three different groups (normal, acute OM, and chronic OM) and with longitudinal image-based analysis of ear infections were included in this study. The nsOCT data were correlated with physician diagnosis and with OCT thickness measurements and were found to be in good agreement with these results. We report that nsOCT detects in vivo structural deformations of the TM earlier than OCT alone, and enhances the detection sensitivity of OCT measurements. This unique technique for early detection of nano-scale structural modifications in the TM has the potential to aid in our understanding of microbiological effects, and possibly for early diagnosis and more effective treatment of OM.
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Affiliation(s)
- Roshan Dsouza
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Jungeun Won
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Guillermo L Monroy
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Malcolm C Hill
- Department of Pediatrics, Carle Foundation Hospital, Urbana, Illinois, USA
- Carle-Illinois College of Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Ryan G Porter
- Carle-Illinois College of Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
- Department of Otolaryngology, Carle Foundation Hospital, Urbana, Illinois, USA
| | - Michael A Novak
- Carle-Illinois College of Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
- Department of Otolaryngology, Carle Foundation Hospital, Urbana, Illinois, USA
| | - Stephen A Boppart
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA.
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA.
- Carle-Illinois College of Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA.
- Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA.
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Leahy M, Thompson K, Zafar H, Alexandrov S, Foley M, O'Flatharta C, Dockery P. Functional imaging for regenerative medicine. Stem Cell Res Ther 2016; 7:57. [PMID: 27095443 PMCID: PMC4837501 DOI: 10.1186/s13287-016-0315-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
In vivo imaging is a platform technology with the power to put function in its natural structural context. With the drive to translate stem cell therapies into pre-clinical and clinical trials, early selection of the right imaging techniques is paramount to success. There are many instances in regenerative medicine where the biological, biochemical, and biomechanical mechanisms behind the proposed function of stem cell therapies can be elucidated by appropriate imaging. Imaging techniques can be divided according to whether labels are used and as to whether the imaging can be done in vivo. In vivo human imaging places additional restrictions on the imaging tools that can be used. Microscopies and nanoscopies, especially those requiring fluorescent markers, have made an extraordinary impact on discovery at the molecular and cellular level, but due to their very limited ability to focus in the scattering tissues encountered for in vivo applications they are largely confined to superficial imaging applications in research laboratories. Nanoscopy, which has tremendous benefits in resolution, is limited to the near-field (e.g. near-field scanning optical microscope (NSNOM)) or to very high light intensity (e.g. stimulated emission depletion (STED)) or to slow stochastic events (photo-activated localization microscopy (PALM) and stochastic optical reconstruction microscopy (STORM)). In all cases, nanoscopy is limited to very superficial applications. Imaging depth may be increased using multiphoton or coherence gating tricks. Scattering dominates the limitation on imaging depth in most tissues and this can be mitigated by the application of optical clearing techniques that can impose mild (e.g. topical application of glycerol) or severe (e.g. CLARITY) changes to the tissue to be imaged. Progression of therapies through to clinical trials requires some thought as to the imaging and sensing modalities that should be used. Smoother progression is facilitated by the use of comparable imaging modalities throughout the discovery and trial phases, giving label-free techniques an advantage wherever they can be used, although this is seldom considered in the early stages. In this paper, we will explore the techniques that have found success in aiding discovery in stem cell therapies and try to predict the likely technologies best suited to translation and future directions.
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Affiliation(s)
- Martin Leahy
- Tissue Optics & Microcirculation Imaging Group, School of Physics, National University of Ireland (NUI), Galway, Ireland. .,Chair of Applied Physics, National University of Ireland (NUI), Galway, Ireland.
| | - Kerry Thompson
- Centre for Microscopy and Imaging, Anatomy, School of Medicine, National University of Ireland (NUI), Galway, Ireland
| | - Haroon Zafar
- Tissue Optics & Microcirculation Imaging Group, School of Physics, National University of Ireland (NUI), Galway, Ireland
| | - Sergey Alexandrov
- Tissue Optics & Microcirculation Imaging Group, School of Physics, National University of Ireland (NUI), Galway, Ireland
| | - Mark Foley
- Medical Physics Research Cluster, School of Physics, National University of Ireland (NUI), Galway, Ireland
| | - Cathal O'Flatharta
- Regenerative Medicine Institute (REMEDI), National University of Ireland (NUI), Galway, Ireland
| | - Peter Dockery
- Centre for Microscopy and Imaging, Anatomy, School of Medicine, National University of Ireland (NUI), Galway, Ireland
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Alexandrov SA, Subhash HM, Zam A, Leahy M. Nano-sensitive optical coherence tomography. NANOSCALE 2014; 6:3545-9. [PMID: 24595392 DOI: 10.1039/c3nr06132a] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Depth resolved label-free detection of structural changes with nanoscale sensitivity is an outstanding problem in the biological and physical sciences and has significant applications in both the fundamental research and healthcare diagnostics arenas. Here we experimentally demonstrate a novel label-free depth resolved sensing technique based on optical coherence tomography (OCT) to detect structural changes at the nanoscale. Structural components of the 3D object, spectrally encoded in the remitted light, are transformed from the Fourier domain into each voxel of the 3D OCT image without compromising sensitivity. Spatial distribution of the nanoscale structural changes in the depth direction is visualized in just a single OCT scan. This label free approach provides new possibilities for depth resolved study of pathogenic and physiologically relevant molecules in the body with high sensitivity and specificity. It offers a powerful opportunity for early diagnosis and treatment of diseases. Experimental results show the ability of the approach to differentiate structural changes of 30 nm in nanosphere aggregates, located at different depths, from a single OCT scan, and structural changes less than 30 nm in time from two OCT scans. Application for visualization of the structure of human skin in vivo is also demonstrated.
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Affiliation(s)
- Sergey A Alexandrov
- NBIPI Tissue Optics & Microcirculation Imaging Group, School of Physics, National University of Ireland, Galway, Ireland.
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Liu Y, Uttam S, Alexandrov S, Bista RK. Investigation of nanoscale structural alterations of cell nucleus as an early sign of cancer. BMC BIOPHYSICS 2014; 7:1. [PMID: 24507508 PMCID: PMC3928095 DOI: 10.1186/2046-1682-7-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Accepted: 02/05/2014] [Indexed: 12/18/2022]
Abstract
Background The cell and tissue structural properties assessed with a conventional bright-field light microscope play a key role in cancer diagnosis, but they sometimes have limited accuracy in detecting early-stage cancers or predicting future risk of cancer progression for individual patients (i.e., prognosis) if no frank cancer is found. The recent development in optical microscopy techniques now permit the nanoscale structural imaging and quantitative structural analysis of tissue and cells, which offers a new opportunity to investigate the structural properties of cell and tissue below 200 – 250 nm as an early sign of carcinogenesis, prior to the presence of microscale morphological abnormalities. Identification of nanoscale structural signatures is significant for earlier and more accurate cancer detection and prognosis. Results Our group has recently developed two simple spectral-domain optical microscopy techniques for assessing 3D nanoscale structural alterations – spectral-encoding of spatial frequency microscopy and spatial-domain low-coherence quantitative phase microscopy. These two techniques use the scattered light from biological cells and tissue and share a common experimental approach of assessing the Fourier space by various wavelengths to quantify the 3D structural information of the scattering object at the nanoscale sensitivity with a simple reflectance-mode light microscopy setup without the need for high-NA optics. This review paper discusses the physical principles and validation of these two techniques to interrogate nanoscale structural properties, as well as the use of these methods to probe nanoscale nuclear architectural alterations during carcinogenesis in cancer cell lines and well-annotated human tissue during carcinogenesis. Conclusions The analysis of nanoscale structural characteristics has shown promise in detecting cancer before the microscopically visible changes become evident and proof-of-concept studies have shown its feasibility as an earlier or more sensitive marker for cancer detection or diagnosis. Further biophysical investigation of specific 3D nanoscale structural characteristics in carcinogenesis, especially with well-annotated human cells and tissue, is much needed in cancer research.
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Affiliation(s)
- Yang Liu
- Biomedical Optical Imaging Laboratory, Department of Medicine, Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
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Uttam S, Alexandrov SA, Bista RK, Liu Y. Tomographic imaging via spectral encoding of spatial frequency. OPTICS EXPRESS 2013; 21:7488-504. [PMID: 23546131 PMCID: PMC3635700 DOI: 10.1364/oe.21.007488] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Revised: 01/28/2013] [Accepted: 02/04/2013] [Indexed: 05/24/2023]
Abstract
Three-dimensional optical tomographic imaging plays an important role in biomedical research and clinical applications. We introduce spectral tomographic imaging (STI) via spectral encoding of spatial frequency principle that not only has the capability for visualizing the three-dimensional object at sub-micron resolution but also providing spatially-resolved quantitative characterization of its structure with nanoscale accuracy for any volume of interest within the object. The theoretical basis and the proof-of-concept numerical simulations are presented to demonstrate the feasibility of spectral tomographic imaging.
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Affiliation(s)
- Shikhar Uttam
- Biomedical and Optical Imaging Laboratory (BOIL), Departments of Medicine and Bioengineering, University of Pittsburgh, Pittsburgh PA 15213, USA.
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