Dr. Karthik Vishwanath Profile

Dr. Karthik Vishwanath

at Miami University

SPIE Involvement:

Author | Science Fair Judge

Area of Expertise:

Biomedical optics , Steady state and time-resolved spectroscopy , Radiative transport , Monte Carlo , Optical properties

Websites:

Company Website

Publications (35)

SPIE Journal Paper | 12 March 2024 Open Access

Can diffuse reflectance spectroscopy identify shuntodynia in pediatric hydrocephalus patients?

Olivia Kline, Karthik Vishwanath, Boyd Colbrunn, Andrew Peachman, Jing Zhang, Sudhakar Vadivelu

JBO, Vol. 29, Issue 03, 037002, (March 2024) https://doi.org/10.1117/12.10.1117/1.JBO.29.3.037002

KEYWORDS: Tissues, Tissue optics, Statistical analysis, Data modeling, Hemodynamics, Oxygen, Diffuse reflectance spectroscopy, Scattering, Reflectivity, Skin

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SignificanceShuntodynia is patient reported pain at the site of the implanted ventriculoperitoneal (VP) shunt. Pediatric hydrocephalus requiring shunt placement is a chronic and prevalent standard of care treatment and requires lifetime management. Shuntodynia is a subjective measure of shunt dysfunction. Quantitative, white-light tissue spectroscopy could be used to objectively identify this condition in the clinic.AimPediatric subjects were recruited for optical sensing during routine clinical follow-up visits, post-VP shunt implantations. Acquired optical signals were translated into skin-hemodynamic signatures and were compared between subjects that reported shuntodynia versus those that did not.ApproachDiffuse reflectance spectroscopy (DRS) measurements were collected between 450 and 700 nm using a single-channel fiber-optical probe from (N=35) patients. Multiple reflectance spectra were obtained by the attending physician from regions both proximal and distal to the VP shunt sites and from a matched contralateral site for each subject. Acquired reflectance spectra were processed quantitatively into functional tissue optical endpoints. A two-way, repeated measures analysis of variance was used to assess whether and which of the optical variables were statistically separable, across subjects with shuntodynia versus those without.ResultsAnalyses indicated that intrapatient differences in vascular oxygen saturation measured between shunt sites relative to that obtained at the scar or contralateral sites was significantly lower in the pain group. We also find that the total hemoglobin concentrations at the shunt site were lowest relative to the other sites for subjects reporting pain. These findings suggest that shuntodynia pain arises in the scalp tissue around the implanted shunts and may be caused due to hypoxia and inflammation.ConclusionsOptically derived hemodynamic variables were statistically significantly different in subjects presenting with shuntodynia relative to those without. DRS could provide a viable mode in routine bedside monitoring of subjects with VP shunts for clinical management and assessment of shuntodynia.

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Proceedings Article | 16 March 2023 Presentation + Paper

UV-excited autofluorescence responses from cells embedded in turbid media containing hemoglobin analyzed using spectral phasors

Paul Urayama, Mary McNeill, Blake McClain, Nick Majer, Karthik Vishwanath

Proceedings Volume 12391, 123910I (2023) https://doi.org/10.1117/12.2650783

KEYWORDS: Absorption, Autofluorescence, Cyanide, Turbidity, Spectral response, Fluorophores, Fluorescence

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Proceedings Article | 3 March 2022 Paper

Time-gated diffuse reflectance to discriminate optical properties of two-layered tissue phantoms

Carter McMaster, Michael Helton, Boyd Colbrunn, Mary-Ann Mycek, Karthik Vishwanath

Proceedings Volume 11974, 119740C (2022) https://doi.org/10.1117/12.2610392

KEYWORDS: Optical phantoms, Tissue optics, Diffuse reflectance spectroscopy, Absorption, Scattering

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Proceedings Article | 3 March 2022 Paper

Investigating the use of diffuse reflectance spectroscopy to identify shuntodynia

Olivia Kline, Boyd Colbrunn, Andrew Peachman, Sudhakar Vadivelu, Karthik Vishwanath

Proceedings Volume 11974, 119740B (2022) https://doi.org/10.1117/12.2610159

KEYWORDS: Scattering, Skin, Absorption, Tissue optics, Diffuse reflectance spectroscopy

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Proceedings Article | 3 March 2022 Presentation + Paper

Neural networks to solve forward and inverse problems in diffuse reflectance spectroscopy

Qing Lan, Ryan McClarren, Karthik Vishwanath

Proceedings Volume 12019, 120190L (2022) https://doi.org/10.1117/12.2610530

KEYWORDS: Neural networks, Diffuse reflectance spectroscopy, Data modeling, Monte Carlo methods, Scattering, Optical properties, Inverse problems, Inverse optics, Absorption

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Proceedings Article | 2 March 2022 Paper

Development of a portable, non-contact diffuse reflectance system for tissue spectroscopy

Bradley Clemson, Michael Mrsan, Karthik Vishwanath

Proceedings Volume 11953, 119530L (2022) https://doi.org/10.1117/12.2610438

KEYWORDS: Multiple scattering, Specular reflections, Diffuse reflectance spectroscopy, Absorption, Tissue optics

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Proceedings Article | 5 March 2021 Presentation + Paper

Distinguishing cellular respiration vs. oxidative stress in turbid media using UV-excited autofluorescence spectroscopy

Paul Urayama, Taylor Phillips, Thomas Finn, Bibek Dhakal, Karthik Vishwanath

Proceedings Volume 11655, 1165507 (2021) https://doi.org/10.1117/12.2578724

KEYWORDS: Spectroscopy, Luminescence, Image segmentation, Chemical analysis, Yeast, Tissues, Multiple scattering, Mode conditioning cables, Hyperspectral imaging, Hydrogen

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Proceedings Article | 5 March 2021 Presentation + Paper

Neural network forward model and transfer learning calibration from Monte Carlo to diffuse reflectance spectroscopy

Qing Lan, Ryan McClarren, Karthik Vishwanath

Proceedings Volume 11639, 116390E (2021) https://doi.org/10.1117/12.2581556

KEYWORDS: Calibration, Monte Carlo methods, Neural networks, Diffuse reflectance spectroscopy, Diffuse optical spectroscopy, Data modeling, Spectral calibration, Inverse problems, Tissue optics, Scattering

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Proceedings Article | 5 March 2021 Presentation + Paper

Calibration free, time-resolved diffuse optical spectroscopy using combined Monte-Carlo and diffusion theory

Michael Helton, Carter McMaster, Mary-Ann Mycek, Karthik Vishwanath

Proceedings Volume 11657, 116570M (2021) https://doi.org/10.1117/12.2583283

KEYWORDS: Calibration, Diffusion, Diffuse optical spectroscopy, Optical properties, Reflectivity, Tissue optics, Scattering, Optical components, Monte Carlo methods, Absorption

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Proceedings Article | 21 February 2020 Paper

Directly extracting the optical transport coefficients of a turbid medium via time-resolved diffuse reflectance: a Monte Carlo study

Michael Helton, Mary-Ann Mycek, Karthik Vishwanath

Proceedings Volume 11253, 112530O (2020) https://doi.org/10.1117/12.2543610

KEYWORDS: Monte Carlo methods, Optical properties, Scattering, Absorption, Tissues, Diffuse reflectance spectroscopy, Reflectivity, Picosecond phenomena, Sensors, Point spread functions

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Proceedings Article | 20 February 2020 Paper

Spectral phasor analysis of autofluorescence responses from cells embedded in turbid media containing collagen

Max Kreider, Andrew Rodriguez, Karthik Vishwanath, Paul Urayama

Proceedings Volume 11251, 112510B (2020) https://doi.org/10.1117/12.2546398

KEYWORDS: Cyanide, Collagen, Tissues, Yeast, Luminescence, Fluorescence spectroscopy, Laser induced fluorescence, Biological and chemical sensing

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Proceedings Article | 17 February 2020 Presentation + Paper

Lateral light losses in integrating sphere measurements: comparison of Monte-Carlo with inverse adding-doubling algorithm

Vinoin Devpaul Vincely, Karthik Vishwanath

Proceedings Volume 11231, 112310G (2020) https://doi.org/10.1117/12.2546265

KEYWORDS: Optical properties, Absorption, Scattering, Tissue optics, Integrating spheres, Monte Carlo methods

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Proceedings Article | 9 March 2018 Paper

Investigating the depth-sensitivity of laser speckle contrast imaging in flow phantoms

Anthony Young, Karthik Vishwanath

Proceedings Volume 10573, 105732Z (2018) https://doi.org/10.1117/12.2294480

KEYWORDS: Laser speckle contrast imaging, Speckle, Scattering, Tissue optics

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Proceedings Article | 9 March 2018 Paper

Sensitivity of diffuse correlation spectroscopy to flow rates: a study with tissue simulating optical phantoms

Sara Zanfardino, Karthik Vishwanath

Proceedings Volume 10573, 105732K (2018) https://doi.org/10.1117/12.2293952

KEYWORDS: Scattering, Absorption, Optical phantoms, Spectroscopy

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Proceedings Article | 19 February 2018 Paper

Extracting broadband optical properties from uniform optical phantoms using an integrating sphere and inverse adding-doubling

Vinoin Vincely, Karthik Vishwanath

Proceedings Volume 10486, 1048615 (2018) https://doi.org/10.1117/12.2291950

KEYWORDS: Tissue optics, Optical properties

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SPIE Journal Paper | 14 December 2017 Open Access

Compact dual-mode diffuse optical system for blood perfusion monitoring in a porcine model of microvascular tissue flaps

Seung Yup Lee, Julia Pakela, Michael Helton, Karthik Vishwanath, Yooree Chung, Noah Kolodziejski, Christopher Stapels, Daniel McAdams, Daniel Fernandez, James Christian, Jameson O'Reilly, Dana Farkas, Brent Ward, Stephen Feinberg, Mary-Ann Mycek

JBO, Vol. 22, Issue 12, 121609, (December 2017) https://doi.org/10.1117/12.10.1117/1.JBO.22.12.121609

KEYWORDS: Optical fibers, Skin, Arteries, Tissue optics, Blood, Blood circulation, Tissues, Surgery, Diffuse reflectance spectroscopy, Reflectivity

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Proceedings Article | 3 March 2017 Paper

The reliability and accuracy of estimating heart-rates from RGB video recorded on a consumer grade camera

Adam Eaton, Vinoin Vincely, Paige Lloyd, Kurt Hugenberg, Karthik Vishwanath

Proceedings Volume 10055, 100550Y (2017) https://doi.org/10.1117/12.2252629

KEYWORDS: Video, Video processing, RGB color model, Cameras, Principal component analysis, Machine vision, Computer vision technology, Skin, Beam propagation method, Signal processing

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Proceedings Article | 17 February 2017 Paper

Design verification of a compact system for detecting tissue perfusion using bimodal diffuse optical technologies

Julia Pakela, Taylor Hedrick, Seung Yup Lee, Karthik Vishwanath, Sara Zanfardino, Yooree Chung, Michael Helton, Noah Kolodziejski, Christopher Stapels, Daniel McAdams, Daniel Fernandez, James Christian, Stephen Feinberg, Mary-Ann Mycek

Proceedings Volume 10072, 1007217 (2017) https://doi.org/10.1117/12.2252811

KEYWORDS: Tissue optics, Diffuse reflectance spectroscopy, Reflectance spectroscopy, Tissues, Liquids, Biomedical optics, Spectroscopy, Optical properties, Fiber optics, Blood circulation, Data analysis, Reflectivity, In vivo imaging, Scattering

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Proceedings Article | 17 February 2017 Paper

In vivo preclinical verification of a multimodal diffuse reflectance and correlation spectroscopy system for sensing tissue perfusion

Julia Pakela, Seung Yup Lee, Taylor Hedrick, Karthik Vishwanath, Michael Helton, Yooree Chung, Noah Kolodziejski, Christopher Staples, Daniel McAdams, Daniel Fernandez, James Christian, Jameson O'Reilly, Dana Farkas, Brent Ward, Stephen Feinberg, Mary-Ann Mycek

Proceedings Volume 10072, 100720U (2017) https://doi.org/10.1117/12.2252620

KEYWORDS: Sensing systems, Reflectance spectroscopy, Tissues, Blood circulation, Blood, In vivo imaging, Diffuse reflectance spectroscopy, Spectroscopes, Tissue optics, Arteries, Skin, Optical fibers, Reflectivity

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Proceedings Article | 14 February 2017 Paper

Novel diffuse optics system for continuous tissue viability monitoring: extended recovery in vivo testing in a porcine flap model

Seung Yup Lee, Julia Pakela, Taylor Hedrick, Karthik Vishwanath, Michael Helton, Yooree Chung, Noah Kolodziejski, Christopher Stapels, Daniel McAdams, Daniel Fernandez, James Christian, Jameson O'Reilly, Dana Farkas, Brent Ward, Stephen Feinberg, Mary-Ann Mycek

Proceedings Volume 10054, 1005413 (2017) https://doi.org/10.1117/12.2252295

KEYWORDS: Tissues, Reflectance spectroscopy, Arteries, Tissue optics, In vivo imaging, Diffuse reflectance spectroscopy, Blood circulation, Surgery, Fiber optics, Veins, Reflectivity, Spectroscopy, Skin, Optical correlators

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Proceedings Article | 17 March 2016 Paper

Quantitative assessment of reactive hyperemia using laser speckle contrast imaging at multiple wavelengths

Anthony Young, Karthik Vishwanath

Proceedings Volume 9707, 97071H (2016) https://doi.org/10.1117/12.2213179

KEYWORDS: Laser speckle contrast imaging, Tissues, Speckle, Hemodynamics, Coherence imaging, Laser tissue interaction, Image processing, In vivo imaging, Functional imaging, Cameras, Light sources, Particles, Scattering, Imaging systems

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Proceedings Article | 29 February 2016 Paper

Monitoring longitudinal changes in irradiated head and neck cancer xenografts using diffuse reflectance spectroscopy

Karthik Vishwanath, Shudong Jiang, Jason Gunn, Kayla Marra, Jacqueline Andreozzi, Brian Pogue

Proceedings Volume 9689, 96891W (2016) https://doi.org/10.1117/12.2213192

KEYWORDS: Head, Neck, Cancer, Diffuse reflectance spectroscopy, Radiotherapy, Tissues, Tumors, Chromium, Electron beams, X-rays

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Proceedings Article | 4 March 2014 Paper

Sensing vascularization of ex-vivo produced oral mucosal equivalent (EVPOME) skin grafts in nude mice using optical spectroscopy

Karthik Vishwanath, Rajan Gurjar, Shiuhyang Kuo, Anthony Fasi, Roderick Kim, Suzannah Riccardi, Stephen Feinberg, David Wolf

Proceedings Volume 8926, 89260I (2014) https://doi.org/10.1117/12.2037085

KEYWORDS: Tissues, Skin, Tissue optics, Blood circulation, Signal detection, Optical fibers, Injuries, Composites, Laser induced plasma spectroscopy, Diffuse reflectance spectroscopy

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Proceedings Article | 4 March 2014 Paper

Extracting optical properties of turbid media using radially and spectrally resolved diffuse reflectance

Jonathan Malsan, Rajan Gurjar, David Wolf, Karthik Vishwanath

Proceedings Volume 8936, 893615 (2014) https://doi.org/10.1117/12.2039964

KEYWORDS: Optical properties, Absorption, Scattering, Solids, Reflectivity, Diffuse reflectance spectroscopy, Monte Carlo methods, Liquids, Sensors, Tissue optics

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SPIE Journal Paper | 31 July 2012 Open Access

Publisher's Note: Experimental validation of an inverse fluorescence Monte Carlo model to extract concentrations of metabolically relevant fluorophores from turbid phantoms and a murine tumor model

Chengbo Liu, Narasimhan Rajaram, Karthik Vishwanath, Tony Jiang, Nirmala Ramanujam, Gregory Palmer

JBO, Vol. 17, Issue 7, 079805, (July 2012) https://doi.org/10.1117/12.10.1117/1.JBO.17.7.079805

KEYWORDS: Luminescence, Monte Carlo methods, Tumors, Instrument modeling, Biomedical optics, Biomedical engineering, Biological research, Life sciences, Roads, Radiation oncology

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SPIE Journal Paper | 24 July 2012 Open Access

Experimental validation of an inverse fluorescence Monte Carlo model to extract concentrations of metabolically relevant fluorophores from turbid phantoms and a murine tumor model

Chengbo Liu, Narasimhan Rajaram, Karthik Vishwanath, Tony Jiang, Nirmala Ramanujam, Gregory Palmer

JBO, Vol. 17, Issue 7, 077012, (July 2012) https://doi.org/10.1117/12.10.1117/1.JBO.17.7.077012

KEYWORDS: Luminescence, Monte Carlo methods, Absorption, Calibration, Reflectivity, Tissues, Rhodamine, Scattering, Optical properties, Tissue optics

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SPIE Journal Paper | 1 September 2009 Open Access

Quantitative optical spectroscopy can identify long-term local tumor control in irradiated murine head and neck xenografts

Karthik Vishwanath, Daniel Klein, Kevin Chang, Thies Schroeder, Mark Dewhirst, Nirmala Ramanujam

JBO, Vol. 14, Issue 05, 054051, (September 2009) https://doi.org/10.1117/12.10.1117/1.3251013

KEYWORDS: Tumors, Diffuse reflectance spectroscopy, Cancer, Chromium, Head, Neck, Optical spectroscopy, Oncology, Animal model studies, Tumor growth modeling

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Proceedings Article | 25 February 2009 Paper

Combined Monte Carlo and path-integral method for simulated library of time-resolved reflectance curves from layered tissue models

Robert Wilson, Karthik Vishwanath, Mary-Ann Mycek

Proceedings Volume 7175, 717518 (2009) https://doi.org/10.1117/12.808423

KEYWORDS: Tissue optics, Tissues, Reflectivity, Monte Carlo methods, Absorption, Scattering, Photon transport, Computer simulations, Mathematical modeling, Astronomical imaging

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Proceedings Article | 24 February 2009 Paper

Frequency domain 3D simplified spherical harmonics approximation: development, validation, and implication in bioluminescence imaging

M. Chu, A. Klose, I. Styles, K. Vishwanath, H. Dehghani

Proceedings Volume 7174, 717422 (2009) https://doi.org/10.1117/12.808756

KEYWORDS: 3D modeling, Data modeling, Monte Carlo methods, Absorption, Spherical lenses, Optical properties, Bioluminescence, Photon transport, Diffusion, 3D image processing

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Proceedings Article | 19 July 2007 Paper

Semi-analytical method for rapid calculation of time-resolved reflectance from bi-layered tissue models

Robert Wilson, Karthik Vishwanath, Mary-Ann Mycek

Proceedings Volume 6628, 66280W (2007) https://doi.org/10.1117/12.729431

KEYWORDS: Tissues, Reflectivity, Absorption, Tissue optics, Monte Carlo methods, Computer simulations, Scattering, Photon transport, Optical properties, Anisotropy

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Proceedings Article | 11 July 2007 Paper

Sensing metabolic activity in tissue engineered constructs

Malavika Chandra, Robert Wilson, Wen-Liang Lo, Karthik Vishwanath, Kenji Izumi, Stephen Feinberg, Mary-Ann Mycek

Proceedings Volume 6628, 66280B (2007) https://doi.org/10.1117/12.729426

KEYWORDS: Luminescence, Tissues, Monte Carlo methods, Collagen, Signal detection, Sensors, Tissue optics, Fluorescence spectroscopy, Absorption, Natural surfaces

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Proceedings Article | 8 October 2005 Paper

Computer aided visualizations of 3-dimensional light distributions in tissues for quantitative optical diagnostics

Karthik Vishwanath, Mary-Ann Mycek

Proceedings Volume 5862, 58620M (2005) https://doi.org/10.1117/12.633026

KEYWORDS: Tissues, Luminescence, Monte Carlo methods, Scattering, Absorption, Fluorescence spectroscopy, Sensors, Signal detection, Visualization, Tissue optics

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Proceedings Article | 29 July 2003 Paper

Effects of tissue optical properties on time-resolved fluorescence measurements from brain tumors: an experimental and computational study

Pramod Butte, Karthik Vishwanath, Brian Pikul, Mary-Ann Mycek, Laura Marcu

Proceedings Volume 4955, (2003) https://doi.org/10.1117/12.478192

KEYWORDS: Brain, Tissue optics, Scattering, Tissues, Luminescence, Reflectivity, Laser scattering, Tumors, Diffusion, Optical properties

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Proceedings Article | 29 July 2003 Paper

Internal refractive index changes affect light transport in tissue

Ben Brooksby, Hamid Dehghani, Karthik Vishwanath, Brian Pogue, Keith Paulsen

Proceedings Volume 4955, (2003) https://doi.org/10.1117/12.477365

KEYWORDS: Refractive index, Tissue optics, Tissues, Monte Carlo methods, Scattering, Optical properties, Absorption, Photons, Refraction, 3D modeling

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Proceedings Article | 22 July 2003 Paper

Simulations of time-resolved fluorescence in multilayered biological tissues: applications to clinical data modeling

Mary-Ann Mycek, Karthik Vishwanath, Brian Pogue, Kevin Schomacker, Norman Nishioka

Proceedings Volume 4958, (2003) https://doi.org/10.1117/12.476135

KEYWORDS: Tissues, Monte Carlo methods, Luminescence, Time resolved spectroscopy, Absorption, Quantum efficiency, Collagen, Colon, Pathology, In vivo imaging

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Showing 5 of 35 publications

Conference Committee Involvement (1)

Preclinical and Clinical Optical Diagnostics

23 June 2019 | Munich, Germany

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