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Knighton NJ, Cottle BK, Tiwari S, Mondal A, Kaza AK, Sachse FB, Hitchcock RW. Toward cardiac tissue characterization using machine learning and light-scattering spectroscopy. JOURNAL OF BIOMEDICAL OPTICS 2021; 26:JBO-200330RR. [PMID: 34729970 PMCID: PMC8562351 DOI: 10.1117/1.jbo.26.11.116001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 10/12/2021] [Indexed: 06/13/2023]
Abstract
SIGNIFICANCE The non-destructive characterization of cardiac tissue composition provides essential information for both planning and evaluating the effectiveness of surgical interventions such as ablative procedures. Although several methods of tissue characterization, such as optical coherence tomography and fiber-optic confocal microscopy, show promise, many barriers exist that reduce effectiveness or prevent adoption, such as time delays in analysis, prohibitive costs, and limited scope of application. Developing a rapid, low-cost non-destructive means of characterizing cardiac tissue could improve planning, implementation, and evaluation of cardiac surgical procedures. AIM To determine whether a new light-scattering spectroscopy (LSS) system that analyzes spectra via neural networks is capable of predicting the nuclear densities (NDs) of ventricular tissues. APPROACH We developed an LSS system with a fiber-optics probe and applied it for measurements on cardiac tissues from an ovine model. We quantified the ND in the cardiac tissues using fluorescent labeling, confocal microscopy, and image processing. Spectra acquired from the same cardiac tissues were analyzed with spectral clustering and convolutional neural networks (CNNs) to assess the feasibility of characterizing the ND of tissue via LSS. RESULTS Spectral clustering revealed distinct groups of spectra correlated to ranges of ND. CNNs classified three groups of spectra with low, medium, or high ND with an accuracy of 95.00 ± 11.77 % (mean and standard deviation). Our analyses revealed the sensitivity of the classification accuracy to wavelength range and subsampling of spectra. CONCLUSIONS LSS and machine learning are capable of assessing ND in cardiac tissues. We suggest that the approach is useful for the diagnosis of cardiac diseases associated with changes of ND, such as hypertrophy and fibrosis.
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Affiliation(s)
- Nathan J. Knighton
- University of Utah, Department of Biomedical Engineering, Salt Lake City, United States
- University of Utah, Nora Eccles Harrison Cardiovascular Research and Training Institute, Salt Lake City, United States
| | - Brian K. Cottle
- University of Utah, Department of Biomedical Engineering, Salt Lake City, United States
- University of Utah, Nora Eccles Harrison Cardiovascular Research and Training Institute, Salt Lake City, United States
| | - Sarthak Tiwari
- University of Utah, Department of Biomedical Engineering, Salt Lake City, United States
- University of Utah, Nora Eccles Harrison Cardiovascular Research and Training Institute, Salt Lake City, United States
| | - Abhijit Mondal
- Boston Children’s Hospital, Harvard Medical School, Department of Cardiac Surgery, Boston, United States
| | - Aditya K. Kaza
- Boston Children’s Hospital, Harvard Medical School, Department of Cardiac Surgery, Boston, United States
| | - Frank B. Sachse
- University of Utah, Department of Biomedical Engineering, Salt Lake City, United States
- University of Utah, Nora Eccles Harrison Cardiovascular Research and Training Institute, Salt Lake City, United States
| | - Robert W. Hitchcock
- University of Utah, Department of Biomedical Engineering, Salt Lake City, United States
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Lu W, Pei Z, Hu W, Tan C, Tong X, Feng Y, Sun X. Recent progress in optical clearing of eye tissues. Exp Eye Res 2021; 212:108796. [PMID: 34662543 DOI: 10.1016/j.exer.2021.108796] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2021] [Revised: 08/20/2021] [Accepted: 10/13/2021] [Indexed: 12/21/2022]
Abstract
The growing need for viewing the detailed 3D structures of various tissues and organs requires advanced tissue processing and imaging techniques. However, light scattering by tissues hinders detailed structural observations. To overcome this, the emerging technique of "tissue optical clearing" has been flourishing in recent decades, providing excellent opportunities for imaging deep, micro-scale structures of various organs, or even of the whole body. In recent years, advanced tissue clearing techniques have been optimized for specific tissues and organs. Among these tissues, the eye is unique owing to its delicate structure and pigmented retinal epithelial cells, calling for more work on making these tissues "transparent". In this review, we searched Medline and Embase for studies published between January 2006 and August 2021 using the terms "tissue optical clearing", "ophthalmology", "eye", and "optical clearing agents", and we reviewed the publications on the optical clearing techniques of eye tissue from 2006 to the present, including both the clearing procedures and the subsequent analytical processes, thus gaining more insight into the application of tissue optical clearing in basic eye research. Furthermore, we discuss the future potential of optical clearing applications in clinical ophthalmology.
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Affiliation(s)
- Wenhan Lu
- Department of Ophthalmology & Visual Science, Eye & ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, 200031, China; Department of Integrative Medicine and Neurobiology, State Key Lab of Medical Neurobiology, Institute of Integrative Medicine of Fudan University, Institute of Brain Science, School of Basic Medical Sciences, Fudan University, Shanghai, 200032, China
| | - Zhenle Pei
- Department of Integrative Medicine and Neurobiology, State Key Lab of Medical Neurobiology, Institute of Integrative Medicine of Fudan University, Institute of Brain Science, School of Basic Medical Sciences, Fudan University, Shanghai, 200032, China
| | - Wei Hu
- Department of Integrative Medicine and Neurobiology, State Key Lab of Medical Neurobiology, Institute of Integrative Medicine of Fudan University, Institute of Brain Science, School of Basic Medical Sciences, Fudan University, Shanghai, 200032, China
| | - Chen Tan
- Department of Ophthalmology & Visual Science, Eye & ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, 200031, China
| | - Xiaoyu Tong
- Department of Integrative Medicine and Neurobiology, State Key Lab of Medical Neurobiology, Institute of Integrative Medicine of Fudan University, Institute of Brain Science, School of Basic Medical Sciences, Fudan University, Shanghai, 200032, China
| | - Yi Feng
- Department of Integrative Medicine and Neurobiology, State Key Lab of Medical Neurobiology, Institute of Integrative Medicine of Fudan University, Institute of Brain Science, School of Basic Medical Sciences, Fudan University, Shanghai, 200032, China.
| | - Xinghuai Sun
- Department of Ophthalmology & Visual Science, Eye & ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, 200031, China; State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, 200032, China; NHC Key Laboratory of Myopia, Chinese Academy of Medical Sciences, And Shanghai Key Laboratory of Visual Impairment and Restoration (Fudan University), Shanghai, 200031, China.
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Towards Intraoperative Quantification of Atrial Fibrosis Using Light-Scattering Spectroscopy and Convolutional Neural Networks. SENSORS 2021; 21:s21186033. [PMID: 34577240 PMCID: PMC8471003 DOI: 10.3390/s21186033] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 09/03/2021] [Accepted: 09/06/2021] [Indexed: 01/06/2023]
Abstract
Light-scattering spectroscopy (LSS) is an established optical approach for characterization of biological tissues. Here, we investigated the capabilities of LSS and convolutional neural networks (CNNs) to quantitatively characterize the composition and arrangement of cardiac tissues. We assembled tissue constructs from fixed myocardium and the aortic wall with a thickness similar to that of the atrial free wall. The aortic sections represented fibrotic tissue. Depth, volume fraction, and arrangement of these fibrotic insets were varied. We gathered spectra with wavelengths from 500–1100 nm from the constructs at multiple locations relative to a light source. We used single and combinations of two spectra for training of CNNs. With independently measured spectra, we assessed the accuracy of the CNNs for the classification of tissue constructs from single spectra and combined spectra. Combined spectra, including the spectra from fibers distal from the illumination fiber, typically yielded the highest accuracy. The maximal classification accuracy of the depth detection, volume fraction, and permutated arrangements was (mean ± standard deviation (stddev)) 88.97 ± 2.49%, 76.33 ± 1.51%, and 84.25 ± 1.88%, respectively. Our studies demonstrate the reliability of quantitative characterization of tissue composition and arrangements using a combination of LSS and CNNs. The potential clinical applications of the developed approach include intraoperative quantification and mapping of atrial fibrosis, as well as the assessment of ablation lesions.
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Bennett A, Davidovitch E, Beiderman Y, Agadarov S, Beiderman Y, Moshkovitz A, Polat U, Zalevsky Z. Corneal thickness measurement by secondary speckle tracking and image processing using machine-learning algorithms. JOURNAL OF BIOMEDICAL OPTICS 2019; 24:1-10. [PMID: 31797646 PMCID: PMC7005539 DOI: 10.1117/1.jbo.24.12.126001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Accepted: 11/04/2019] [Indexed: 06/10/2023]
Abstract
Corneal thickness (CoT) is an important tool in the evaluation process for several disorders and in the assessment of intraocular pressure. We present a method enabling high-precision measurement of CoT based on secondary speckle tracking and processing of the information by machine-learning (ML) algorithms. The proposed configuration includes capturing by fast camera the laser beam speckle patterns backscattered from the corneal-scleral border, followed by ML processing of the image. The technique was tested on a series of phantoms having different thicknesses as well as in clinical trials on human eyes. The results show high accuracy in determination of eye CoT, and implementation is speedy in comparison with other known measurement methods.
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Affiliation(s)
- Aviya Bennett
- Bar-Ilan University, Faculty of Engineering, Nanotechnology Center, Ramat-Gan, Israel
| | - Elnatan Davidovitch
- Bar-Ilan University, Faculty of Engineering, Nanotechnology Center, Ramat-Gan, Israel
| | - Yafim Beiderman
- Bar-Ilan University, Faculty of Engineering, Nanotechnology Center, Ramat-Gan, Israel
| | - Sergey Agadarov
- Bar-Ilan University, Faculty of Engineering, Nanotechnology Center, Ramat-Gan, Israel
| | - Yevgeny Beiderman
- Bar-Ilan University, Faculty of Engineering, Nanotechnology Center, Ramat-Gan, Israel
| | - Avital Moshkovitz
- Bar-Ilan University, School of Optometry and Vision Science, Ramat-Gan, Israel
| | - Uri Polat
- Bar-Ilan University, School of Optometry and Vision Science, Ramat-Gan, Israel
| | - Zeev Zalevsky
- Bar-Ilan University, Faculty of Engineering, Nanotechnology Center, Ramat-Gan, Israel
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Dynamics of Pivoting Electrical Waves in a Cardiac Tissue Model. Bull Math Biol 2019; 81:2649-2690. [PMID: 31201662 DOI: 10.1007/s11538-019-00623-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 05/27/2019] [Indexed: 10/26/2022]
Abstract
Through a detailed mathematical analysis we seek to advance our understanding of how cardiac tissue conductances govern pivoting (spiral, scroll, rotor, functional reentry) wave dynamics. This is an important problem in cardiology since pivoting waves likely underlie most reentrant tachycardias. The problem is complex, and to advance our methods of analysis we introduce two new tools: a ray tracing method and a moving-interface model. When used in combination with an ionic model, they permit us to elucidate the role played by tissue conductances on pivoting wave dynamics. Specifically we simulate traveling electrical waves with an ionic model that can reproduce the characteristics of plane and pivoting waves in small patches of cardiac tissue. Then ray tracing is applied to the simulated pivoting waves in a manner to expose their real displacement. In this exercise we find loci with special characteristics, as well as zones where a part of a pivoting wave quickly transitions from a regenerative to a non-regenerative propagation mode. The loci themselves and the monitoring of the ionic model state variables in this zone permit to elucidate several aspects of pivoting wave dynamics. We then formulate the moving-interface model based on the information gathered with the above-mentioned analysis. Equipped with a velocity profile v(s), s: distance along of the pivoting wave contour and the steady- state action potential duration (APD) of a plane wave during entrainment, APDss(T), at period T, this simple model can predict: shape, orbit of revolution, rotation period, whether a pivoting wave will break up or not, and whether the tissue will admit pivoting waves or not. Because v(s) and APDss(T) are linked to the ionic model, dynamical analysis with the moving-interface model conveys information on the role played by tissue conductances on pivoting wave dynamics. The analysis conducted here enables us to better understand previous results on the termination of pivoting waves. We surmise the method put forth here could become a means to discover how to alter tissue conductances in a manner to terminate pivoting waves at the origin of reentrant tachycardias.
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