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Sullender CT, Mark AE, Clark TA, Esipova TV, Vinogradov SA, Jones TA, Dunn AK. Imaging of cortical oxygen tension and blood flow following targeted photothrombotic stroke. NEUROPHOTONICS 2018; 5:035003. [PMID: 30137881 PMCID: PMC6062776 DOI: 10.1117/1.nph.5.3.035003] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Accepted: 07/02/2018] [Indexed: 05/24/2023]
Abstract
We present a dual-modality imaging system combining laser speckle contrast imaging and oxygen-dependent quenching of phosphorescence to simultaneously map cortical blood flow and oxygen tension ( pO 2 ) in mice. Phosphorescence signal localization is achieved through the use of a digital micromirror device (DMD) that allows for selective excitation of arbitrary regions of interest. By targeting both excitation maxima of the oxygen-sensitive Oxyphor PtG4, we are able to examine the effects of excitation wavelength on the measured phosphorescence lifetime. We demonstrate the ability to measure the differences in pO 2 between arteries and veins and large changes during a hyperoxic challenge. We dynamically monitor blood flow and pO 2 during DMD-targeted photothrombotic occlusion of an arteriole and highlight the presence of an ischemia-induced depolarization. Chronic tracking of the ischemic lesion over eight days revealed a rapid recovery, with the targeted vessel fully reperfusing and pO 2 returning to baseline values within five days. This system has broad applications for studying the acute and chronic pathophysiology of ischemic stroke and other vascular diseases of the brain.
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Affiliation(s)
- Colin T. Sullender
- University of Texas at Austin, Department of Biomedical Engineering, Austin, Texas, United States
| | - Andrew E. Mark
- University of Texas at Austin, Department of Biomedical Engineering, Austin, Texas, United States
| | - Taylor A. Clark
- University of Texas at Austin, Department of Psychology, Austin, Texas, United States
- University of Texas at Austin, Institute for Neuroscience, Austin, Texas, United States
| | - Tatiana V. Esipova
- University of Pennsylvania, Department of Biochemistry and Biophysics, Philadelphia, Pennsylvania, United States
| | - Sergei A. Vinogradov
- University of Pennsylvania, Department of Biochemistry and Biophysics, Philadelphia, Pennsylvania, United States
| | - Theresa A. Jones
- University of Texas at Austin, Department of Psychology, Austin, Texas, United States
- University of Texas at Austin, Institute for Neuroscience, Austin, Texas, United States
| | - Andrew K. Dunn
- University of Texas at Austin, Department of Biomedical Engineering, Austin, Texas, United States
- University of Texas at Austin, Institute for Neuroscience, Austin, Texas, United States
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Campbell CL, Wood K, Brown CTA, Moseley H. Monte Carlo modelling of photodynamic therapy treatments comparing clustered three dimensional tumour structures with homogeneous tissue structures. Phys Med Biol 2016; 61:4840-54. [PMID: 27273196 DOI: 10.1088/0031-9155/61/13/4840] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
We explore the effects of three dimensional (3D) tumour structures on depth dependent fluence rates, photodynamic doses (PDD) and fluorescence images through Monte Carlo radiation transfer modelling of photodynamic therapy. The aim with this work was to compare the commonly used uniform tumour densities with non-uniform densities to determine the importance of including 3D models in theoretical investigations. It was found that fractal 3D models resulted in deeper penetration on average of therapeutic radiation and higher PDD. An increase in effective treatment depth of 1 mm was observed for one of the investigated fractal structures, when comparing to the equivalent smooth model. Wide field fluorescence images were simulated, revealing information about the relationship between tumour structure and the appearance of the fluorescence intensity. Our models indicate that the 3D tumour structure strongly affects the spatial distribution of therapeutic light, the PDD and the wide field appearance of surface fluorescence images.
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Affiliation(s)
- C L Campbell
- School of Physics and Astronomy, University of St Andrews, UK
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Kazmi SMS, Faraji E, Davis MA, Huang YY, Zhang XJ, Dunn AK. Flux or speed? Examining speckle contrast imaging of vascular flows. BIOMEDICAL OPTICS EXPRESS 2015. [PMID: 26203384 PMCID: PMC4505712 DOI: 10.1364/boe.6.002588] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Speckle contrast imaging enables rapid mapping of relative blood flow distributions using camera detection of back-scattered laser light. However, speckle derived flow measures deviate from direct measurements of erythrocyte speeds by 47 ± 15% (n = 13 mice) in vessels of various calibers. Alternatively, deviations with estimates of volumetric flux are on average 91 ± 43%. We highlight and attempt to alleviate this discrepancy by accounting for the effects of multiple dynamic scattering with speckle imaging of microfluidic channels of varying sizes and then with red blood cell (RBC) tracking correlated speckle imaging of vascular flows in the cerebral cortex. By revisiting the governing dynamic light scattering models, we test the ability to predict the degree of multiple dynamic scattering across vessels in order to correct for the observed discrepancies between relative RBC speeds and multi-exposure speckle imaging estimates of inverse correlation times. The analysis reveals that traditional speckle contrast imagery of vascular flows is neither a measure of volumetric flux nor particle speed, but rather the product of speed and vessel diameter. The corrected speckle estimates of the relative RBC speeds have an average 10 ± 3% deviation in vivo with those obtained from RBC tracking.
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Affiliation(s)
- S. M. Shams Kazmi
- The University of Texas at Austin, Department of Biomedical Engineering, 107 W. Dean Keeton C0800, Austin, Texas 78712, USA
| | - Ehssan Faraji
- The University of Texas at Austin, Department of Biomedical Engineering, 107 W. Dean Keeton C0800, Austin, Texas 78712, USA
| | - Mitchell A. Davis
- The University of Texas at Austin, Department of Biomedical Engineering, 107 W. Dean Keeton C0800, Austin, Texas 78712, USA
| | - Yu-Yen Huang
- The University of Texas at Austin, Department of Biomedical Engineering, 107 W. Dean Keeton C0800, Austin, Texas 78712, USA
- Currently with Dartmouth College, Thayer School of Engineering, 14 Engineering Drive, Hanover, New Hampshire 03755, USA
| | - Xiaojing J. Zhang
- The University of Texas at Austin, Department of Biomedical Engineering, 107 W. Dean Keeton C0800, Austin, Texas 78712, USA
- Currently with Dartmouth College, Thayer School of Engineering, 14 Engineering Drive, Hanover, New Hampshire 03755, USA
| | - Andrew K. Dunn
- The University of Texas at Austin, Department of Biomedical Engineering, 107 W. Dean Keeton C0800, Austin, Texas 78712, USA
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Davis MA, Dunn AK. Dynamic light scattering Monte Carlo: a method for simulating time-varying dynamics for ordered motion in heterogeneous media. OPTICS EXPRESS 2015; 23:17145-17155. [PMID: 26191723 PMCID: PMC4523555 DOI: 10.1364/oe.23.017145] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Revised: 06/10/2015] [Accepted: 06/11/2015] [Indexed: 05/29/2023]
Abstract
Few methods exist that can accurately handle dynamic light scattering in the regime between single and highly multiple scattering. We demonstrate dynamic light scattering Monte Carlo (DLS-MC), a numerical method by which the electric field autocorrelation function may be calculated for arbitrary geometries if the optical properties and particle motion are known or assumed. DLS-MC requires no assumptions regarding the number of scattering events, the final form of the autocorrelation function, or the degree of correlation between scattering events. Furthermore, the method is capable of rapidly determining the effect of particle motion changes on the autocorrelation function in heterogeneous samples. We experimentally validated the method and demonstrated that the simulations match both the expected form and the experimental results. We also demonstrate the perturbation capabilities of the method by calculating the autocorrelation function of flow in a representation of mouse microvasculature and determining the sensitivity to flow changes as a function of depth.
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Affiliation(s)
- Mitchell A. Davis
- Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78712,
USA
| | - Andrew K. Dunn
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX 78712,
USA
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Davis MA, Kazmi SMS, Dunn AK. Imaging depth and multiple scattering in laser speckle contrast imaging. JOURNAL OF BIOMEDICAL OPTICS 2014; 19:086001. [PMID: 25089945 PMCID: PMC4119427 DOI: 10.1117/1.jbo.19.8.086001] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Revised: 05/15/2014] [Accepted: 06/23/2014] [Indexed: 05/18/2023]
Abstract
Laser speckle contrast imaging (LSCI) is a powerful and simple method for full field imaging of blood flow. However, the depth dependence and the degree of multiple scattering have not been thoroughly investigated. We employ three-dimensional Monte Carlo simulations of photon propagation combined with high resolution vascular anatomy to investigate these two issues. We found that 95% of the detected signal comes from the top 700 μm of tissue. Additionally, we observed that single-intravascular scattering is an accurate description of photon sampling dynamics, but that regions of interest (ROIs) in areas free of obvious surface vessels had fewer intravascular scattering events than ROI over resolved surface vessels. Furthermore, we observed that the local vascular anatomy can strongly affect the depth dependence of LSCI. We performed simulations over a wide range of intravascular and extravascular scattering properties to confirm the applicability of these results to LSCI imaging over a wide range of visible and near-infrared wavelengths.
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Affiliation(s)
- Mitchell A. Davis
- The University of Texas at Austin, Department of Electrical and Computer Engineering, Austin, Texas 78712, United States
| | - S. M. Shams Kazmi
- The University of Texas at Austin, Department of Biomedical Engineering, Austin, Texas 78712, United States
| | - Andrew K. Dunn
- The University of Texas at Austin, Department of Biomedical Engineering, Austin, Texas 78712, United States
- Address all correspondence to: Andrew K. Dunn, E-mail:
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