1
|
Yu PK, Mehnert A, Dickson JB, Qambari H, Balaratnasingam C, Cringle S, Darcey D, Yu DY. Quantitative study of spatial and temporal variation in retinal capillary network perfusion in rat eye by in vivo confocal imaging. Sci Rep 2023; 13:18923. [PMID: 37919331 PMCID: PMC10622421 DOI: 10.1038/s41598-023-44480-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Accepted: 10/09/2023] [Indexed: 11/04/2023] Open
Abstract
Microvascular dysfunction is the underlying pathological process in many systemic diseases. However, investigation into its pathogenesis is impeded by the accessibility and complexity of the microvasculature within different organs, particularly for the central nervous system. The retina as an extension of the cerebrum provides a glimpse into the brain through which the microvasculature can be observed. Two major questions remain unanswered: How do the microvessels regulate spatial and temporal delivery to satisfy the varying cellular demands, and how can we quantify blood perfusion in the 3D capillary network? Here, quantitative measurements of red blood cell (RBC) speed in each vessel in the field were made in the in vivo rat retinal capillary network using an ultrafast confocal technique with fluorescently labelled RBCs. Retinal RBC speed and number were found to vary remarkably between microvessels ranging from 215 to 6641 microns per second with significant variations spatially and temporally. Overall, the RBC speed was significantly faster in the microvessels in the superficial retina than in the deep retina (estimated marginal means of 2405 ± 238.2 µm/s, 1641 ± 173.0 µm/s respectively). These observations point to a highly dynamic nature of microvasculature that is specific to its immediate cellular environment and is constantly changing.
Collapse
Affiliation(s)
- Paula Kun Yu
- Centre for Ophthalmology and Visual Science, The University of Western Australia, Perth, Australia
- Lions Eye Institute, 2 Verdun Street, Nedlands, WA, Australia
| | - Andrew Mehnert
- Centre for Ophthalmology and Visual Science, The University of Western Australia, Perth, Australia
- Lions Eye Institute, 2 Verdun Street, Nedlands, WA, Australia
| | | | - Hassanain Qambari
- Centre for Ophthalmology and Visual Science, The University of Western Australia, Perth, Australia
- Lions Eye Institute, 2 Verdun Street, Nedlands, WA, Australia
| | - Chandrakumar Balaratnasingam
- Centre for Ophthalmology and Visual Science, The University of Western Australia, Perth, Australia
- Lions Eye Institute, 2 Verdun Street, Nedlands, WA, Australia
- Department of Ophthalmology, Sir Charles Gairdner Hospital, Nedlands, WA, Australia
| | - Stephen Cringle
- Centre for Ophthalmology and Visual Science, The University of Western Australia, Perth, Australia
- Lions Eye Institute, 2 Verdun Street, Nedlands, WA, Australia
| | - Dean Darcey
- Lions Eye Institute, 2 Verdun Street, Nedlands, WA, Australia
| | - Dao-Yi Yu
- Centre for Ophthalmology and Visual Science, The University of Western Australia, Perth, Australia.
- Lions Eye Institute, 2 Verdun Street, Nedlands, WA, Australia.
| |
Collapse
|
2
|
Tsai J, Asanad S, Whiting M, Zhang X, Magder L, Saeedi O. Repeatability and Comparability of Retinal Blood Vessel Caliber Measurements by OCTA. Vision (Basel) 2023; 7:48. [PMID: 37489327 PMCID: PMC10366731 DOI: 10.3390/vision7030048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 05/23/2023] [Accepted: 06/16/2023] [Indexed: 07/26/2023] Open
Abstract
BACKGROUND To investigate the repeatability in vessel caliber measurements by optical coherence tomography angiography (OCTA). METHODS In this prospective study, 28 patients (47 eyes) underwent sequential OCTA imaging of the optic nerve head and macula. Two independent masked graders measured vessel caliber for sequential images of the optic nerve head and macula. The average vessel width was determined and variability between graders and images. RESULTS A total of 8400 measurements of 420 vessels from 84 OCTA images were included in the analysis. Overall, inter-grader agreement was excellent (ICC 0.90). The coefficient of variation (CoV) for all repeated OCTA images was 0.10. Greater glaucoma severity, older age, macular location, and diagnosis of diabetes were associated with thinner vessels (p < 0.05). CoV was higher in the peripapillary region (0.07) as compared to the macula (0.15). ICC was high for all subgroups except for the macula (ICC = 0.72). CONCLUSIONS Overall, the repeatability of vessel caliber measurements by OCTA was high and variability low. There was greater variability in the measurement of macular vessels, possibly due to technical limitations in acquiring accurate vessel widths for smaller macular vessels.
Collapse
Affiliation(s)
- Joby Tsai
- Department of Ophthalmology, Broward Health, Deerfield Beach, FL 33064, USA
| | - Samuel Asanad
- Department of Ophthalmology and Visual Sciences, University of Maryland, Baltimore, MD 21201, USA
| | - Martha Whiting
- Department of Ophthalmology and Visual Sciences, University of Maryland, Baltimore, MD 21201, USA
| | - Xuemin Zhang
- Department of Ophthalmology and Visual Sciences, University of Maryland, Baltimore, MD 21201, USA
| | - Laurence Magder
- Department of Epidemiology and Public Health, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Osamah Saeedi
- Department of Ophthalmology and Visual Sciences, University of Maryland, Baltimore, MD 21201, USA
| |
Collapse
|
3
|
Liu R, Wang X, Hoshi S, Zhang Y. High-speed measurement of retinal arterial blood flow in the living human eye with adaptive optics ophthalmoscopy. OPTICS LETTERS 2023; 48:1994-1997. [PMID: 37058625 DOI: 10.1364/ol.480896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Accepted: 03/06/2023] [Indexed: 06/19/2023]
Abstract
We present a technique to measure the rapid blood velocity in large retinal vessels with high spatiotemporal resolution. Red blood cell motion traces in the vessels were non-invasively imaged using an adaptive optics near-confocal scanning ophthalmoscope at a frame rate of 200 fps. We developed software to measure blood velocity automatically. We demonstrated the ability to measure the spatiotemporal profiles of the pulsatile blood flow with a maximum velocity of 95-156 mm/s in retinal arterioles with a diameter >100 µm. High-speed and high-resolution imaging increased the dynamic range, enhanced sensitivity, and improved the accuracy when studying retinal hemodynamics.
Collapse
|
4
|
Albright A, Fry BC, Verticchio A, Siesky B, Harris A, Arciero J. Metabolic blood flow regulation in a hybrid model of the human retinal microcirculation. Math Biosci 2023; 357:108969. [PMID: 36702235 PMCID: PMC10015448 DOI: 10.1016/j.mbs.2023.108969] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 01/17/2023] [Accepted: 01/17/2023] [Indexed: 01/25/2023]
Abstract
The retinal vascular network supplies perfusion to vital visual structures, including retinal ganglion cells responsible for vision. Impairments in retinal blood flow and oxygenation are involved in the progression of many ocular diseases, including glaucoma. In this study, an established theoretical hybrid model of a retinal microvascular network is extended to include the effects of local blood flow regulation on oxygenation. A heterogeneous representation of the arterioles based on confocal microscopy images is combined with a compartmental description of the downstream capillaries and venules. A Green's function method is used to simulate oxygen transport in the arterioles, and a Krogh cylinder model is applied to the capillary and venular compartments. Acute blood flow regulation is simulated in response to changes in pressure, shear stress, and metabolism. Model results predict that both increased intraocular pressure and impairment of blood flow regulation can cause decreased tissue oxygenation, indicating that both mechanisms represent factors that could lead to impaired oxygenation characteristic of ocular disease. Results also indicate that the metabolic response mechanism reduces the fraction of poorly oxygenated tissue but that the pressure- and shear stress-dependent response mechanisms may hinder the vascular response to changes in oxygenation. Importantly, the heterogeneity of the vascular network demonstrates that traditionally reported average values of tissue oxygen levels hide significant localized defects in tissue oxygenation that may be involved in disease processes, including glaucoma. Ultimately, the model framework presented in this study will facilitate future comparisons to sectorial-specific clinical data to better assess the role of impaired blood flow regulation in ocular disease.
Collapse
Affiliation(s)
- Amanda Albright
- Department of Mathematical Sciences, Indiana University-Purdue University Indianapolis, 402 N. Blackford St, LD 270, Indianapolis, IN 46202, USA
| | - Brendan C Fry
- Department of Mathematics and Statistics, Metropolitan State University of Denver, P.O. Box 173362, Campus Box 38, Denver, CO 80217, USA
| | - Alice Verticchio
- Department of Ophthalmology, Icahn School of Medicine at Mount Sinai Hospital, One Gustave L. Levy Place, Box 1183, New York, NY 10029, USA
| | - Brent Siesky
- Department of Ophthalmology, Icahn School of Medicine at Mount Sinai Hospital, One Gustave L. Levy Place, Box 1183, New York, NY 10029, USA
| | - Alon Harris
- Department of Ophthalmology, Icahn School of Medicine at Mount Sinai Hospital, One Gustave L. Levy Place, Box 1183, New York, NY 10029, USA
| | - Julia Arciero
- Department of Mathematical Sciences, Indiana University-Purdue University Indianapolis, 402 N. Blackford St, LD 270, Indianapolis, IN 46202, USA.
| |
Collapse
|
5
|
Liu Y, Yu S, Zhang Y, Liu X. Label-free full-field Doppler phase microscopy based on optical computation. BIOMEDICAL OPTICS EXPRESS 2023; 14:441-452. [PMID: 36698679 PMCID: PMC9842006 DOI: 10.1364/boe.479255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 12/08/2022] [Accepted: 12/09/2022] [Indexed: 06/17/2023]
Abstract
The capability to image subtle mechanical motion at cellular and sub-cellular scales can be used to study how extracellular particles interact with cultured cells and, more generally, how cells interact with their environment. However, current technologies need to provide sufficient spatial resolution, temporal resolution, and motion sensitivity to image cellular and sub-cellular motion in the en face plane. To address this unmet need, we investigate a full-field Doppler phase microscopy (FF-DPM) technology based on an innovative optical computation strategy that enables depth-resolved imaging and phase quantification. In this study, we validated the motion tracking (displacements and velocities) capability of FF-DPM by imaging samples actuated by a piezo transducer (PZT). We demonstrated FF-DPM imaging of magnetic particles under different conditions with different motion characteristics. Our results show that free particles (suspended in a cell culture medium) had a significantly larger magnitude of motion than particles adhered to a cell. The key innovation of this study is the use of an optical computation strategy to perform depth-resolved phase quantification and Doppler measurement. The FF-DPM will have a significant impact, as it provides a unique capability to quantitatively measure subtle motion for models based on cultured cells.
Collapse
Affiliation(s)
- Yuwei Liu
- Department of Electrical and Computer Engineering, New Jersey Institute of Technology, University Heights, Newark, New Jersey, 07105, USA
| | - Shupei Yu
- Department of Cheminstry and Environmental Science, New Jersey Institute of Technology, University Heights, Newark, New Jersey, 07105, USA
| | - Yuanwei Zhang
- Department of Cheminstry and Environmental Science, New Jersey Institute of Technology, University Heights, Newark, New Jersey, 07105, USA
| | - Xuan Liu
- Department of Electrical and Computer Engineering, New Jersey Institute of Technology, University Heights, Newark, New Jersey, 07105, USA
| |
Collapse
|
6
|
Pappelis K, Jansonius NM. Retinal Oxygen Delivery and Extraction in Ophthalmologically Healthy Subjects With Different Blood Pressure Status. Transl Vis Sci Technol 2022; 11:9. [PMID: 35119472 PMCID: PMC8819358 DOI: 10.1167/tvst.11.2.9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose To compare retinal oxygen delivery (DO2) and oxygen extraction (VO2) in ophthalmologically healthy subjects with different blood pressure (BP) status. Methods In this case-control study, we prospectively included 93 eyes of 93 subjects (aged 50-65 years) from a Dutch cohort (n = 167,000) and allocated them to four groups (low BP, normal BP [controls], treated arterial hypertension [AHT], untreated AHT). We estimated vascular calibers from fundus images and fractal dimension from optical coherence tomography angiography scans. We combined calibers, fractal dimension, BP, and intraocular pressure measurements in a proxy of retinal blood flow (RBF), using a Poiseuille-based model. We measured arterial and venous oxygen saturations (SaO2, SvO2) with a scanning laser ophthalmoscope. We calculated the DO2 and VO2 from the RBF, SaO2, and SvO2. We compared the DO2 and VO2 between groups and investigated the DO2-VO2 association. Results DO2 and VO2 were different between groups (P = 0.009, P = 0.036, respectively). In a post hoc analysis, the low BP group had lower DO2 than the untreated AHT group (P = 4.9 × 10-4). The low BP group and the treated AHT group had a lower VO2 than the untreated AHT group (P = 0.021 and P = 0.034, respectively). There was a significant DO2-VO2 correlation (Robs = 0.65, bobs = 0.51, P = 2.4 × 10-12). After correcting for shared measurement error, the slope was not significant. Conclusions The DO2 and VO2 were altered in ophthalmologically healthy subjects with different BP status. Future studies could elucidate whether these changes can explain the increased risk of ophthalmic pathologies in those subjects. Translational Relevance Understanding the baseline interplay between BP, retinal perfusion, and oxygenation allows for improved evaluation of retinal disease manifestation.
Collapse
Affiliation(s)
- Konstantinos Pappelis
- Department of Ophthalmology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands.,Graduate School of Medical Sciences (Research School of Behavioural and Cognitive Neurosciences), University of Groningen, Groningen, the Netherlands
| | - Nomdo M Jansonius
- Department of Ophthalmology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands.,Graduate School of Medical Sciences (Research School of Behavioural and Cognitive Neurosciences), University of Groningen, Groningen, the Netherlands
| |
Collapse
|
7
|
Rahimi M, Leahy S, Blair NP, Shahidi M. Variability of Retinal Oxygen Metrics in Healthy and Diabetic Subjects. Transl Vis Sci Technol 2021; 10:20. [PMID: 34661625 PMCID: PMC8525846 DOI: 10.1167/tvst.10.12.20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose Previous studies have reported alterations in total retinal blood flow (TRBF), oxygen delivery (DO2), oxygen metabolism (MO2), and oxygen extraction fraction (OEF) due to retinal diseases. The purposes of the current study were to determine variabilities and establish normal confidence intervals (CIs) for these metrics. Methods A total of 22 healthy and 14 diabetic subjects participated in the study. Retinal vascular oxygen saturation (SO2) and TRBF were measured by oximetry and Doppler optical coherence tomography, respectively. DO2, MO2, and OEF were calculated from SO2 and TRBF measurements. Means, standard deviations (SDs), and CIs of metrics were determined in healthy subjects. Intra-visit variability was determined by the mean SDs of repeated measurements. Inter-visit variability was determined by the difference of measurements between two visits. Results TRBF was 44 ± 15 µL/min (95% CI, 37-51) in healthy subjects. Intra-visit variabilities of TRBF were 5 µL/min and 6 µL/min in healthy and diabetic subjects, respectively. Inter-visit variability of TRBF was 3 µL/min in diabetic subjects. DO2, MO2, and OEF were 8.3 ± 2.9 µLO2/min (95% CI, 7.0-9.6), 3.2 ± 0.9 µLO2/min (95% CI, 2.8-3.6), and 0.40 ± 0.08 (95% CI, 0.36-0.43), respectively, in healthy subjects. Inter-visit variabilities of DO2, MO2, and OEF were 0.6 µLO2/min, 0.1 µLO2/min, and 0.03, respectively, in diabetic subjects. Conclusions The findings established variabilities and normal baselines for TRBF, DO2, MO2, and OEF measurements in a small cohort of subjects. Translational Relevance The variability and normal baselines of retinal oxygen metrics may be useful for diagnosing and monitoring patients with retinal diseases.
Collapse
Affiliation(s)
- Mansour Rahimi
- Department of Ophthalmology, USC Roski Eye Institute, Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA
| | - Sophie Leahy
- Department of Ophthalmology, USC Roski Eye Institute, Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA
| | - Norman P Blair
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL, USA
| | - Mahnaz Shahidi
- Department of Ophthalmology, USC Roski Eye Institute, Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA
| |
Collapse
|
8
|
Pappelis K, Jansonius NM. U-Shaped Effect of Blood Pressure on Structural OCT Metrics and Retinal Perfusion in Ophthalmologically Healthy Subjects. Invest Ophthalmol Vis Sci 2021; 62:5. [PMID: 34499704 PMCID: PMC8434757 DOI: 10.1167/iovs.62.12.5] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Purpose We wanted to investigate the association of blood pressure (BP) status with the ganglion cell-inner plexiform layer (GCIPL) and retinal nerve fiber layer (RNFL) thickness of nonglaucomatous eyes and to elucidate whether this effect is related to vascular metrics proxying retinal perfusion. Methods For this case-control study, we prospectively included 96 eyes of 96 healthy subjects (age 50–65) from a large-scale population-based cohort in the northern Netherlands (n = 167,000) and allocated them to four groups (low BP, normal BP [controls], treated arterial hypertension [AHT], untreated AHT). We measured macular GCIPL and RNFL (mRNFL) and peripapillary RNFL (pRNFL) thicknesses with optical coherence tomography (OCT). We estimated retinal blood flow (RBF), retinal vascular resistance (RVR), and autoregulatory reserve (AR) from quantitative OCT-angiography, fundus imaging, BP, and intraocular pressure. We compared structural and vascular metrics across groups and performed mediation analysis. Results Compared to controls, GCIPL was thinner in the low BP group (P = 0.013), treated hypertensives (P = 0.007), and untreated hypertensives (P = 0.007). Treated hypertensives exhibited the thinnest mRNFL (P = 0.001), temporal pRNFL (P = 0.045), and inferior pRNFL (P = 0.034). The association of GCIPL thickness with BP was mediated by RBF within the combined low BP group and controls (P = 0.003), by RVR and AR within the combined treated hypertensives and controls (P = 0.001, P = 0.032), and by RVR within the combined untreated antihypertensives and controls (P = 0.022). Conclusions Inner retinal thinning was associated with both tails of the BP distribution and with ineffective autoregulation. Longitudinal studies could clarify whether these defects can explain the reported glaucomatous predisposition of these population groups.
Collapse
Affiliation(s)
- Konstantinos Pappelis
- Department of Ophthalmology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.,Graduate School of Medical Sciences (Research School of Behavioural and Cognitive Neurosciences), University of Groningen, Groningen, The Netherlands
| | - Nomdo M Jansonius
- Department of Ophthalmology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.,Graduate School of Medical Sciences (Research School of Behavioural and Cognitive Neurosciences), University of Groningen, Groningen, The Netherlands
| |
Collapse
|
9
|
Kim TH, Le D, Son T, Yao X. Vascular morphology and blood flow signatures for differential artery-vein analysis in optical coherence tomography of the retina. BIOMEDICAL OPTICS EXPRESS 2021; 12:367-379. [PMID: 33520388 PMCID: PMC7818960 DOI: 10.1364/boe.413149] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 12/07/2020] [Accepted: 12/09/2020] [Indexed: 05/09/2023]
Abstract
Differential artery-vein (AV) analysis is essential for retinal study, disease detection, and treatment assessment. This study is to characterize vascular reflectance profiles and blood flow patterns of retinal artery and vein systems in optical coherence tomography (OCT) and OCT angiography (OCTA), and establish them as robust signatures for objective AV classification. A custom designed OCT was employed for three-dimensional (3D) imaging of mouse retina, and corresponding OCTA was reconstructed. Radially resliced OCT B-scans revealed two, i.e. top and bottom, hyperreflective wall boundaries in retinal arteries, while these wall boundaries were absent in OCT of retinal veins. Additional OCTA analysis consistently displayed a layered speckle distribution in the vein, which may indicate the venous laminar flow. These OCT and OCTA differences offer unique signatures for objective AV classification in OCT and OCTA.
Collapse
Affiliation(s)
- Tae-Hoon Kim
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - David Le
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Taeyoon Son
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Xincheng Yao
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL 60612, USA
| |
Collapse
|
10
|
Richter D, Fard AM, Straub J, Wei W, Zhang Q, Wang RK. Relative retinal flow velocity detection using optical coherence tomography angiography imaging. BIOMEDICAL OPTICS EXPRESS 2020; 11:6710-6720. [PMID: 33282519 PMCID: PMC7687964 DOI: 10.1364/boe.408481] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 10/19/2020] [Accepted: 10/20/2020] [Indexed: 05/25/2023]
Abstract
Optical coherence tomography angiography (OCTA) imaging is a valuable tool for the visualization of retinal vasculature at an unprecedented level of details. However, due to relatively long time-interval between repeated scans in the conventional OCTA scanning protocol, the OCTA flow signal suffers from low dynamic range and loss of velocity-intensity correlation. The ability to distinguish fast and slow flow in the retina may provide a powerful tool for the assessment of early-stage retinal diseases such as vein occlusion. Here, we report a method to detect relative flow velocity in human retina using a 67.5 kHz spectral-domain OCTA device. By adapting the selection of A-scan time-intervals within a single OCTA acquisition and combining the resulting OCTA images, we expand the detectable velocity range. After a quantitative validation of this method performing microchannel flow experiments with varying flow velocities, we demonstrate this approach on human eyes using CIRRUS HD-OCT 5000 with AngioPlex (ZEISS, Dublin, CA) through a prototype scanning pattern.
Collapse
Affiliation(s)
- Dmitry Richter
- Carl Zeiss Meditec, Inc., Dublin, CA 94568, USA
- Current Address: Wellman Center for Photomedicine, Harvard Medical School and Massachusetts General Hospital, Boston, MA 02114, USA
| | - Ali M Fard
- Carl Zeiss Meditec, Inc., Dublin, CA 94568, USA
| | | | - Wei Wei
- Department of Bioengineering, University of Washington, Seattle, WA 98105, USA
| | - Qinqin Zhang
- Department of Bioengineering, University of Washington, Seattle, WA 98105, USA
| | - Ruikang K Wang
- Department of Bioengineering, University of Washington, Seattle, WA 98105, USA
- Department of Ophthalmology, University of Washington, Seattle, WA 98109, USA
| |
Collapse
|
11
|
Pappelis K, Choritz L, Jansonius NM. Microcirculatory model predicts blood flow and autoregulation range in the human retina: in vivo investigation with laser speckle flowgraphy. Am J Physiol Heart Circ Physiol 2020; 319:H1253-H1273. [PMID: 32986964 DOI: 10.1152/ajpheart.00404.2020] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
In this study, we mathematically predict retinal vascular resistance (RVR) and retinal blood flow (RBF), we test predictions using laser speckle flowgraphy (LSFG), we estimate the range of vascular autoregulation, and we examine the relationship of RBF with the retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC). Fundus, optical coherence tomography (OCT), and OCT-angiography images, systolic/diastolic blood pressure (SBP/DBP), and intraocular pressure (IOP) measurements were obtained from 36 human subjects. We modeled two circulation markers (RVR and RBF) and estimated individualized lower/higher autoregulation limits (LARL/HARL), using retinal vessel calibers, fractal dimension, perfusion pressure, and population-based hematocrit values. Quantitative LSFG waveforms were extracted from vessels of the same eyes, before and during IOP elevation. LSFG metrics explained most variance in RVR (R2 = 0.77/P = 6.9·10-9) and RBF (R2 = 0.65/P = 1.0·10-6), suggesting that the markers strongly reflect blood flow physiology. Higher RBF was associated with thicker RNFL (P = 4.0·10-4) and GCC (P = 0.003), thus also verifying agreement with structural measurements. LARL was at SBP/DBP of 105/65 mmHg for the average subject without arterial hypertension and at 115/75 mmHg for the average hypertensive subject. Moreover, during IOP elevation, changes in RBF were more pronounced than changes in RVR. These observations physiologically imply that healthy subjects are already close to LARL, thus prone to hypoperfusion. In conclusion, we modeled two clinical markers and described a novel method to predict individualized autoregulation limits. These findings could improve understanding of retinal perfusion and pave the way for personalized intervention decisions, when treating patients with coexisting ophthalmic and cardiovascular pathologies.NEW & NOTEWORTHY We describe and test a new approach to quantify retinal blood flow, based on standard clinical examinations and imaging techniques, linked together with a physiological model. We use these findings to generate individualized estimates of the autoregulation range. We provide evidence that healthy subjects are closer to the lower autoregulation limit than thought before. This suggests that some retinas are less prepared to withstand hypoperfusion, even after small intraocular pressure rises or blood pressure drops.
Collapse
Affiliation(s)
- Konstantinos Pappelis
- Department of Ophthalmology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.,Research School of Behavioural and Cognitive Neurosciences, Graduate School of Medical Sciences, University of Groningen, Groningen, The Netherlands
| | - Lars Choritz
- University Eye Clinic, Otto von Guericke University Magdeburg, Magdeburg, Germany
| | - Nomdo M Jansonius
- Department of Ophthalmology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.,Research School of Behavioural and Cognitive Neurosciences, Graduate School of Medical Sciences, University of Groningen, Groningen, The Netherlands
| |
Collapse
|
12
|
Wang T, Pfeiffer T, Daemen J, Mastik F, Wieser W, van der Steen AFW, Huber R, van Soest G. Simultaneous Morphological and Flow Imaging Enabled by Megahertz Intravascular Doppler Optical Coherence Tomography. IEEE TRANSACTIONS ON MEDICAL IMAGING 2020; 39:1535-1544. [PMID: 31725370 DOI: 10.1109/tmi.2019.2948258] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
We demonstrate three-dimensional intravascular flow imaging compatible with routine clinical image acquisition workflow by means of megahertz (MHz) intravascular Doppler Optical Coherence Tomography (OCT). The OCT system relies on a 1.1 mm diameter motorized imaging catheter and a 1.5 MHz Fourier Domain Mode Locked (FDML) laser. Using a post processing method to compensate the drift of the FDML laser output, we can resolve the Doppler phase shift between two adjoining OCT A-line datasets. By interpretation of the velocity field as measured around the zero phase shift, the flow direction at specific angles can be qualitatively estimated. Imaging experiments were carried out in phantoms, micro channels, and swine coronary artery in vitro at a speed of 600 frames/s. The MHz wavelength sweep rate of the OCT system allows us to directly investigate flow velocity of up to 37.5 cm/s while computationally expensive phase-unwrapping has to be applied to measure such high speed using conventional OCT system. The MHz sweep rate also enables a volumetric Doppler imaging even with a fast pullback at 40 mm/s. We present the first simultaneously recorded 3D morphological images and Doppler flow profiles. Flow pattern estimation and three-dimensional structural reconstruction of entire coronary artery are achieved using a single OCT pullback dataset.
Collapse
|
13
|
Ferris NG, Cannon TM, Villiger M, Bouma BE, Uribe-Patarroyo N. Forward multiple scattering dominates speckle decorrelation in whole-blood flowmetry using optical coherence tomography. BIOMEDICAL OPTICS EXPRESS 2020; 11:1947-1966. [PMID: 32341859 PMCID: PMC7173878 DOI: 10.1364/boe.384539] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 03/06/2020] [Accepted: 03/06/2020] [Indexed: 05/22/2023]
Abstract
Quantitative blood flow measurements using optical coherence tomography (OCT) have a wide potential range of medical research and clinical applications. Flowmetry based on the temporal dynamics of the OCT signal may have the ability to measure three-dimensional flow profiles regardless of the flow direction. State-of-the-art models describing the OCT signal temporal statistics are based on dynamic light scattering (DLS), a model which is inherently limited to single scattering regimes. DLS methods continue to be applied to OCT despite the knowledge that red blood cells produce strong forward multiple scattering. Here, we postulate that forward multiple scattering is the primary mechanism causing the rate of speckle-decorrelation derived from data acquired in vivo to deviate from the rate of decorrelation determined in phantom experiments. We also postulate that multiple scattering contributions to decorrelation are only present when the sample exhibits velocity field inhomogeneities larger than the scale of a resolution volume and are thus absent in rigid bulk motion. To test these hypotheses, we performed a systematic study of the effects of forward multiple scattering on OCT signal decorrelation with phantom experiments under physiologically relevant flow conditions and relative bulk motion. Our experimental results confirm that the amount of forward multiple scattering affects the proportionality between lateral flow and decorrelation. We propose that multiply scattered light carries information from different locations in the sample and each location imprints scattering dynamics on the scattered light causing increased decorrelation rates. Our analysis confirms that the detection of forward scattered light inside the vessel lumen causes an increase in the rate of decorrelation which results in an overestimation of blood flow velocities at depths as shallow as 40 µm into whole blood for OCT systems with typical numerical apertures used in retinal imaging.
Collapse
Affiliation(s)
- Natalie G. Ferris
- Wellman Center for Photomedicine, Harvard Medical School and Massachusetts General Hospital, 40 Blossom Street, Boston, Massachusetts 02114, USA
- Harvard-MIT Program in Health Sciences and Technology, Cambridge, Massachusetts 02139, USA
- Harvard Graduate Program in Biophysics, Harvard University Cambridge, Massachusetts 02139, USA
| | - Taylor M. Cannon
- Wellman Center for Photomedicine, Harvard Medical School and Massachusetts General Hospital, 40 Blossom Street, Boston, Massachusetts 02114, USA
- Harvard-MIT Program in Health Sciences and Technology, Cambridge, Massachusetts 02139, USA
| | - Martin Villiger
- Wellman Center for Photomedicine, Harvard Medical School and Massachusetts General Hospital, 40 Blossom Street, Boston, Massachusetts 02114, USA
| | - Brett E. Bouma
- Wellman Center for Photomedicine, Harvard Medical School and Massachusetts General Hospital, 40 Blossom Street, Boston, Massachusetts 02114, USA
- Harvard-MIT Program in Health Sciences and Technology, Cambridge, Massachusetts 02139, USA
- Institute for Medical Engineering and Science, MIT, Massachusetts 02139, USA
| | - Néstor Uribe-Patarroyo
- Wellman Center for Photomedicine, Harvard Medical School and Massachusetts General Hospital, 40 Blossom Street, Boston, Massachusetts 02114, USA
| |
Collapse
|
14
|
Si P, Honkala A, de la Zerda A, Smith BR. Optical Microscopy and Coherence Tomography of Cancer in Living Subjects. Trends Cancer 2020; 6:205-222. [PMID: 32101724 DOI: 10.1016/j.trecan.2020.01.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2019] [Revised: 01/05/2020] [Accepted: 01/07/2020] [Indexed: 12/16/2022]
Abstract
Intravital microscopy (IVM) and optical coherency tomography (OCT) are two powerful optical imaging tools that allow visualization of dynamic biological activities in living subjects with subcellular resolutions. Recent advances in labeling and label-free techniques empower IVM and OCT for a wide range of preclinical and clinical cancer imaging, providing profound insights into the complex physiological, cellular, and molecular behaviors of tumors. Preclinical IVM and OCT have elucidated many otherwise inscrutable aspects of cancer biology, while clinical applications of IVM and OCT are revolutionizing cancer diagnosis and therapies. We review important progress in the fields of IVM and OCT for cancer imaging in living subjects, highlighting key technological developments and their emerging applications in fundamental cancer biology research and clinical oncology investigation.
Collapse
Affiliation(s)
- Peng Si
- Department of Structural Biology, Stanford University, Stanford, CA 94305, USA; Molecular Imaging Program at Stanford, Stanford University, Stanford, CA 94305, USA
| | - Alexander Honkala
- Department of Radiation Oncology, Stanford University, Stanford, CA 94305, USA
| | - Adam de la Zerda
- Department of Structural Biology, Stanford University, Stanford, CA 94305, USA; Molecular Imaging Program at Stanford, Stanford University, Stanford, CA 94305, USA; Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA; The Chan Zuckerberg Biohub, San Francisco, CA 94158, USA.
| | - Bryan Ronain Smith
- Molecular Imaging Program at Stanford, Stanford University, Stanford, CA 94305, USA; Department of Biomedical Engineering and Institute for Quantitative Health Science and Engineering, Michigan State University, East Lansing, MI 48824, USA.
| |
Collapse
|
15
|
Song W, Fu S, Song S, Zhang S, Zhang L, Ness S, Desai M, Yi J. Longitudinal detection of retinal alterations by visible and near-infrared optical coherence tomography in a dexamethasone-induced ocular hypertension mouse model. NEUROPHOTONICS 2019; 6:041103. [PMID: 31312670 PMCID: PMC6614697 DOI: 10.1117/1.nph.6.4.041103] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Accepted: 06/12/2019] [Indexed: 05/23/2023]
Abstract
The retina, as part of the central nervous system, has distinct anatomical and structural properties for its visual function. Light scattering spectroscopy, while widely used for tissue structural characterization and disease diagnosis, has been relatively unexplored in the living retina. Recently, we have developed a fiber-based visible and near-infrared optical coherence tomography system (vnOCT) for in vivo retinal imaging, to uniquely measure a spectroscopic marker (VN ratio) sensitive to nanoscale pathological changes. In the present study, we applied vnOCT in an animal model of glaucoma (dexamethasone-induced ocular hypertension mouse) and tested the capabilities of four optical markers, VN ratio, peripapillary retinal nerve fiber layer (RNFL) thickness, total retinal blood flow, and hemoglobin oxygen saturation ( sO 2 ), for the detection of retinal ganglion cell (RGC) damage in association with ocular hypertension. We found that RNFL-RGC VN ratio and arteriovenous (A-V) sO 2 are capable of detecting early retinal alteration in ocular hypertensive eyes, preceding measurable change of RNFL thickness. This study suggests a potential clinical application of vnOCT in early detection of glaucoma.
Collapse
Affiliation(s)
- Weiye Song
- Boston University School of Medicine, Boston Medical Center, Department of Medicine, Boston, Massachusetts, United States
| | - Sipei Fu
- Boston University, Department of Biology, Boston, Massachusetts, United States
| | - Shangshang Song
- Boston University Sargent School of Rehabilitation, Department of Health Science, Boston, Massachusetts, United States
| | - Sui Zhang
- Dana-Farber Cancer Institute, Boston, Massachusetts, United States
| | - Lei Zhang
- Boston University School of Medicine, Boston Medical Center, Department of Medicine, Boston, Massachusetts, United States
| | - Steven Ness
- Boston Medical Center, Department of Ophthalmology, Boston, Massachusetts, United States
| | - Manishi Desai
- Boston Medical Center, Department of Ophthalmology, Boston, Massachusetts, United States
| | - Ji Yi
- Boston University School of Medicine, Boston Medical Center, Department of Medicine, Boston, Massachusetts, United States
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
| |
Collapse
|
16
|
Kumari R, Sunil D, Ningthoujam RS. Naphthalimides in fluorescent imaging of tumor hypoxia - An up-to-date review. Bioorg Chem 2019; 88:102979. [PMID: 31100616 DOI: 10.1016/j.bioorg.2019.102979] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 04/14/2019] [Accepted: 05/07/2019] [Indexed: 01/17/2023]
Abstract
Hypoxia is a distinctive characteristic of advanced solid malignancies that results from a disparity between oxygen supply and its consumption. The degree of hypoxia is believed to have adverse prognostic significance. Therefore detecting cellular hypoxia can potentially offer insights into the grade of tumour as well as its evolution towards a progressive malignant phenotype, which clinically translates to greater metastatic potential and treatment resistance. Fluorescence imaging to visualize hypoxia in biological systems is a minimally-invasive method. Recently there are several reports on interdisciplinary research that aims at developing functional probes that can be efficiently used for non-invasive imaging of hypoxic tumours. Upregulated levels of nitroreductase (NTR) is detected in hypoxic solid malignancies, and this characteristic feature is increasingly utilized in the development of NTR-targeted fluorescent molecules to selectively sense hypoxia in vivo. The present review summarizes various reports published on the design concepts of nitro naphthalimide-based bio-reductive fluorescent sensors that can be applied noninvasively to image hypoxia in cancer.
Collapse
Affiliation(s)
- Rashmi Kumari
- Department of Chemistry, Manipal Institute of Technology, Manipal Academy of Higher Education, Manipal 576 104, Karnataka, India
| | - Dhanya Sunil
- Department of Chemistry, Manipal Institute of Technology, Manipal Academy of Higher Education, Manipal 576 104, Karnataka, India.
| | | |
Collapse
|
17
|
Shahidi M, Felder AE, Tan O, Blair NP, Huang D. Retinal Oxygen Delivery and Metabolism in Healthy and Sickle Cell Retinopathy Subjects. Invest Ophthalmol Vis Sci 2019; 59:1905-1909. [PMID: 29677351 PMCID: PMC5886143 DOI: 10.1167/iovs.17-23647] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Purpose Reduction in inner retinal oxygen delivery (DO2) can cause retinal hypoxia and impair inner retinal oxygen metabolism (MO2), leading to vision loss. The purpose of the current study was to establish measurements of DO2 and MO2 in healthy subjects and test the hypothesis that DO2 and MO2 are reduced in sickle cell retinopathy (SCR) subjects. Methods Dual wavelength retinal oximetry and Doppler optical coherence tomography were performed in 12 healthy control and 12 SCR subjects. Images were analyzed to measure retinal arterial and venous oxygen content (O2A and O2V), venous diameter (DV), and total retinal blood flow (TRBF). Retinal arteriovenous oxygen content difference (O2AV), DO2, MO2, and oxygen extraction fraction (OEF) were calculated according to the following equations: O2AV = O2A - O2V; DO2 = TRBF * O2A; MO2 = TRBF * O2AV; OEF = MO2/DO2. Results Retinal DV and TRBF were higher in the SCR group as compared to the control group, whereas, O2A, O2V, and O2AV were lower in SCR group as compared to the control group. DO2, MO2, and OEF were not significantly different between control and SCR groups. MO2 and DO2 were linearly related, such that higher MO2 was associated with higher DO2. There was an inverse relationship between TRBF and OEF, such that lower TRBF was associated with higher OEF. Conclusions Increased blood flow compensated for decreased oxygen content, thereby maintaining DO2, MO2, and OEF at predominately lower stages of SCR. Quantitative assessment of these parameters has the potential to advance knowledge and improve diagnostic evaluation of retinal ischemic conditions.
Collapse
Affiliation(s)
- Mahnaz Shahidi
- Department of Ophthalmology, University of Southern California, Los Angeles, California, United States
| | - Anthony E Felder
- Richard and Loan Hill Department of Bioengineering, University of Illinois at Chicago, Chicago, Illinois, United States
| | - Ou Tan
- Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, United States
| | - Norman P Blair
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, Illinois, United States
| | - David Huang
- Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, United States
| |
Collapse
|
18
|
Dadkhah A, Zhou J, Yeasmin N, Jiao S. Integrated multimodal photoacoustic microscopy with OCT- guided dynamic focusing. BIOMEDICAL OPTICS EXPRESS 2019; 10:137-150. [PMID: 30775089 PMCID: PMC6363202 DOI: 10.1364/boe.10.000137] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Revised: 11/27/2018] [Accepted: 11/27/2018] [Indexed: 05/10/2023]
Abstract
Combining different contrast mechanisms to achieve simultaneous multimodal imaging is always desirable but is challenging due to the various optical and hardware requirements for different imaging systems. We developed a multimodal microscopic optical imaging system with the capability of providing comprehensive structural, functional and molecular information of living tissues. This imaging system integrated photoacoustic microscopy (PAM), optical coherence tomography (OCT), optical Doppler tomography (ODT) and confocal fluorescence microscopy in one platform. By taking advantage of the depth resolving capability of OCT, we developed a novel OCT-guided surface contour scanning methodology for dynamic focusing adjustment. We have conducted phantom, in vivo, and ex vivo tests to demonstrate the capability of the multimodal imaging system for providing comprehensive microscopic information of biological tissues. Integrating all the aforementioned imaging modalities with OCT-guided dynamic focusing for simultaneous multimodal imaging has promising potential for preclinical research and clinical practice in the future.
Collapse
Affiliation(s)
- Arash Dadkhah
- Department of Biomedical Engineering, Florida International University, Miami, FL 33174, USA
| | - Jun Zhou
- School of Physics and Information Engineering, Jianghan University, Wuhan, Hubei 430056, China
| | - Nusrat Yeasmin
- Department of Biomedical Engineering, Florida International University, Miami, FL 33174, USA
| | - Shuliang Jiao
- Department of Biomedical Engineering, Florida International University, Miami, FL 33174, USA
| |
Collapse
|
19
|
Wei X, Balne PK, Meissner KE, Barathi VA, Schmetterer L, Agrawal R. Assessment of flow dynamics in retinal and choroidal microcirculation. Surv Ophthalmol 2018; 63:646-664. [DOI: 10.1016/j.survophthal.2018.03.003] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 03/19/2018] [Accepted: 03/19/2018] [Indexed: 01/08/2023]
|
20
|
Gu B, Wang X, Twa MD, Tam J, Girkin CA, Zhang Y. Noninvasive in vivo characterization of erythrocyte motion in human retinal capillaries using high-speed adaptive optics near-confocal imaging. BIOMEDICAL OPTICS EXPRESS 2018; 9:3653-3677. [PMID: 30338146 PMCID: PMC6191635 DOI: 10.1364/boe.9.003653] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Revised: 07/02/2018] [Accepted: 07/02/2018] [Indexed: 05/18/2023]
Abstract
The flow of erythrocytes in parafoveal capillaries was imaged in the living human eye with an adaptive optics near-confocal ophthalmoscope at a frame rate of 800 Hz with a low coherence near-infrared (NIR) light source. Spatiotemporal traces of the erythrocyte movement were extracted from consecutive images. Erythrocyte velocity was measured using custom software based on the Radon transform. The impact of imaging speed on velocity measurement was estimated using images of frame rates of 200, 400, and 800 Hz. The NIR light allowed for long imaging periods without visually stimulating the retina and disturbing the natural rheological state. High speed near-confocal imaging enabled direct and accurate measurement of erythrocyte velocity, and revealed a distinctively cardiac-dependent pulsatile velocity waveform of the erythrocyte flow in retinal capillaries, disclosed the impact of the leukocytes on erythrocyte motion, and provided new metrics for precise assessment of erythrocyte movement. The approach may facilitate new investigations on the pathophysiology of retinal microcirculation with applications for ocular and systemic diseases.
Collapse
Affiliation(s)
- Boyu Gu
- Department of Ophthalmology and Visual Sciences, School of Medicine, University of Alabama at Birmingham, 1670 University Boulevard, Birmingham, AL 35294, USA
| | - Xiaolin Wang
- Department of Ophthalmology and Visual Sciences, School of Medicine, University of Alabama at Birmingham, 1670 University Boulevard, Birmingham, AL 35294, USA
| | - Michael D. Twa
- Department of Optometry and Vision Science, School of Optometry, University of Alabama at Birmingham, 1716 University Boulevard, Birmingham, AL 35294, USA
| | - Johnny Tam
- National Eye Institute, National Institutes of Health, 10 Center Drive, Bethesda, MD 20892, USA
| | - Christopher A. Girkin
- Department of Ophthalmology and Visual Sciences, School of Medicine, University of Alabama at Birmingham, 1670 University Boulevard, Birmingham, AL 35294, USA
| | - Yuhua Zhang
- Department of Ophthalmology and Visual Sciences, School of Medicine, University of Alabama at Birmingham, 1670 University Boulevard, Birmingham, AL 35294, USA
| |
Collapse
|
21
|
Sandhu S, Kydd L, Jaworski J. Luminescent Probe Based Techniques for Hypoxia Imaging. JOURNAL OF NANOMEDICINE RESEARCH 2017; 6:00160. [PMID: 30417104 PMCID: PMC6223636 DOI: 10.15406/jnmr.2017.06.00160] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Hypoxia is a condition of tissue environments wherein a lower than normal level of oxygen is available, and it serves as the root cause and indicator of various diseases. Detection of hypoxia in tumors is imperative for furthering our understanding of the pathological effects and the development of proper treatments, as it is well established that hypoxic tumors are able to impede the cancer treatment process by being resistant to many therapies. It is important therefore to be able to detect hypoxia in tissues and tumors through in vivo imaging methods. A growing area for detection of hypoxia in vivo is the use of fluorescent/luminescent probes which has accelerated in recent years. The continued quest for improvements in selectivity and sensitivity has inspired researchers to pursue new strategies for fluorescence/luminescent probe design. This review will discuss various luminescent probes based on small molecules, dyes, macromolecules, and nanoparticles for sensitive and specific detection of oxygen levels directly or by indirect mechanisms such as the presence of enzymes or related factors that arise in a hypoxic environment. Following the particular mechanism of detection, each probe has specific structural and photophysical properties which permit its selectivity and sensitivity. These probes show promise in terms of low toxicity and high specificity among other merits discussed, and in providing new dimensions for hypoxia detection, these works contribute to future potential methods for clinical diagnosis of hypoxic tissues and tumors.
Collapse
Affiliation(s)
- Sana Sandhu
- Department of Bioengineering, University of Texas at Arlington, USA
| | - LeNaiya Kydd
- Department of Bioengineering, University of Texas at Arlington, USA
| | - Justyn Jaworski
- Department of Bioengineering, University of Texas at Arlington, USA
| |
Collapse
|
22
|
Witkowska KJ, Bata AM, Calzetti G, Luft N, Fondi K, Wozniak PA, Schmidl D, Bolz M, Popa-Cherecheanu A, Werkmeister RM, Garhöfer G, Schmetterer L. Optic nerve head and retinal blood flow regulation during isometric exercise as assessed with laser speckle flowgraphy. PLoS One 2017; 12:e0184772. [PMID: 28898284 PMCID: PMC5595424 DOI: 10.1371/journal.pone.0184772] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Accepted: 08/30/2017] [Indexed: 12/20/2022] Open
Abstract
The aim of the present study was to investigate regulation of blood flow (BF) in the optic nerve head (ONH) and a peripapillary region (PPR) during an isometric exercise-induced increase in ocular perfusion pressure (OPP) using laser speckle flowgraphy (LSFG) in healthy subjects. For this purpose, a total of 27 subjects was included in this study. Mean blur rate in tissue (MT) was measured in the ONH and in a PPR as well as relative flow volume (RFV) in retinal arteries (ART) and veins (VEIN) using LSFG. All participants performed isometric exercise for 6 minutes during which MT and mean arterial pressure were measured every minute. From these data OPP and pressure/flow curves were calculated. Isometric exercise increased OPP, MTONH and MTPRR. The relative increase in OPP (78.5 ± 19.8%) was more pronounced than the increase in BF parameters (MTONH: 18.1 ± 7.7%, MTPRR: 21.1 ± 8.3%, RFVART: 16.5 ±12.0%, RFVVEIN: 17.7 ± 12.4%) indicating for an autoregulatory response of the vasculature. The pressure/flow curves show that MTONH, MTPRR, RFVART, RFVVEIN started to increase at OPP levels of 51.2 ± 2.0%, 58.1 ± 2.4%, 45.6 ± 1.9% and 45.6 ± 1.9% above baseline. These data indicate that ONHBF starts to increase at levels of approx. 50% increase in OPP: This is slightly lower than the values we previously reported from LDF data. Signals from the PPR may have input from both, the retina and the choroid, but the relative contribution is unknown. In addition, retinal BF appears to increase at slightly lower OPP values of approximately 45%. LSFG may be used to study ONH autoregulation in diseases such as glaucoma. Trial Registration: ClinicalTrials.gov NCT02102880
Collapse
Affiliation(s)
| | - Ahmed M. Bata
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
| | | | - Nikolaus Luft
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
- Department of Ophthalmology, Kepler University Hospital, Linz, Austria
| | - Klemens Fondi
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Piotr A. Wozniak
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
- Department of Ophthalmology, Medical University of Warsaw, Warsaw, Poland
| | - Doreen Schmidl
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Matthias Bolz
- Department of Ophthalmology, Kepler University Hospital, Linz, Austria
| | - Alina Popa-Cherecheanu
- Carol Davila University of Medicine and Pharmacy, Bucharest, Romania
- Department of Ophthalmology, Emergency University Hospital, Bucharest, Romania
| | - René M. Werkmeister
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Gerhard Garhöfer
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Leopold Schmetterer
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
- Singapore Eye Research Institute, Singapore, Singapore
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
- * E-mail:
| |
Collapse
|
23
|
Uddin MI, Jayagopal A, McCollum GW, Yang R, Penn JS. In Vivo Imaging of Retinal Hypoxia Using HYPOX-4-Dependent Fluorescence in a Mouse Model of Laser-Induced Retinal Vein Occlusion (RVO). Invest Ophthalmol Vis Sci 2017; 58:3818-3824. [PMID: 28750413 PMCID: PMC5531786 DOI: 10.1167/iovs.16-21187] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose To demonstrate the utility of a novel in vivo molecular imaging probe, HYPOX-4, to detect and image retinal hypoxia in real time, in a mouse model of retinal vein occlusion (RVO). Methods Retinal vein occlusion was achieved in adult mice by photodynamic retinal vein thrombosis (PRVT). One or two major retinal vein(s) was/were occluded in close proximity to the optic nerve head (ONH). In vivo imaging of retinal hypoxia was performed using, HYPOX-4, an imaging probe developed by our laboratory. Pimonidazole-adduct immunostaining was performed and used as a standard ex vivo method for the detection of retinal hypoxia in this mouse RVO model. The retinal vasculature was imaged using fluorescein angiography (FA) and isolectin B4 staining. Retinal thickness was assessed by spectral-domain optical coherence tomography (SD-OCT) analysis. Results By application of the standard ex vivo pimonidazole-adduct immunostaining technique, retinal hypoxia was observed within 2 hours post-PRVT. The observed hypoxic retinal areas depended on whether one or two retinal vein(s) was/were occluded. Similar areas of hypoxia were imaged in vivo using HYPOX-4. Using OCT, retinal edema was observed immediately post-PRVT induction, resolving 8 days later. Nominal preretinal neovascularization was observed at 10 to 14 days post-RVO. Conclusions HYPOX-4 is an efficient probe capable of imaging retinal hypoxia in vivo, in RVO mice. Future studies will focus on its use in correlating retinal hypoxia to the onset and progression of ischemic vasculopathies.
Collapse
Affiliation(s)
- Md Imam Uddin
- Department of Ophthalmology and Visual Sciences, Vanderbilt University School of Medicine, Nashville, Tennessee, United States
| | - Ashwath Jayagopal
- Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche, Ltd. Basel, Switzerland
| | - Gary W McCollum
- Department of Ophthalmology and Visual Sciences, Vanderbilt University School of Medicine, Nashville, Tennessee, United States
| | - Rong Yang
- Department of Ophthalmology and Visual Sciences, Vanderbilt University School of Medicine, Nashville, Tennessee, United States
| | - John S Penn
- Department of Ophthalmology and Visual Sciences, Vanderbilt University School of Medicine, Nashville, Tennessee, United States 2Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche, Ltd. Basel, Switzerland 3Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, United States 4Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States
| |
Collapse
|
24
|
Liu W, Wang S, Soetikno B, Yi J, Zhang K, Chen S, Linsenmeier RA, Sorenson CM, Sheibani N, Zhang HF. Increased Retinal Oxygen Metabolism Precedes Microvascular Alterations in Type 1 Diabetic Mice. Invest Ophthalmol Vis Sci 2017; 58:981-989. [PMID: 28535269 PMCID: PMC5308771 DOI: 10.1167/iovs.16-20600] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Purpose To investigate inner retinal oxygen metabolic rate (IRMRO2) during early stages of type 1 diabetes in a transgenic mouse model. Methods In current study, we involved seven diabetic mice (Akita/+, TSP1−/−) and seven control mice (TSP1−/−), and applied visible-light optical coherence tomography (vis-OCT) to image functional parameters including retinal blood flow rate, oxygen saturation (sO2) and the IRMRO2 value longitudinally from 5 weeks of age to 13 weeks of age. After imaging at 13 weeks of age, we analyzed the imaging results, and examined histology of mouse retina. Results Between diabetic mice and the control group, we observed significant differences in venous sO2 from 9 weeks of age (P = 0.006), and significant increment in IRMRO2 from 11 weeks of age (P = 0.001) in diabetic mice compared with control group. We did not find significant differences in retinal blood flow rate as well as arterial sO2 during imaging between diabetic and control mice. Histologic examination of diabetic and control mice at 13 weeks of age also revealed no anatomical retinal alternations. Conclusions In diabetic retinopathy, complications in retinal oxygen metabolism may occur before changes of retinal anatomical structure.
Collapse
Affiliation(s)
- Wenzhong Liu
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States
| | - Shoujian Wang
- Departments of Ophthalmology and Visual Science, University of Wisconsin, Madison, Wisconsin, United States
| | - Brian Soetikno
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States
| | - Ji Yi
- Department of Medicine, Boston University, Boston, Massachusetts, United States
| | - Kevin Zhang
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States
| | - Siyu Chen
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States
| | - Robert A Linsenmeier
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States 4Department of Ophthalmology, Northwestern University, Chicago, Illinois, United States 5Department of Neurobiology, Northwestern University, Evanston, Illinois, United States
| | - Christine M Sorenson
- Department of Pediatrics, University Wisconsin, Madison, Wisconsin, United States
| | - Nader Sheibani
- Departments of Ophthalmology and Visual Science, University of Wisconsin, Madison, Wisconsin, United States
| | - Hao F Zhang
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States 4Department of Ophthalmology, Northwestern University, Chicago, Illinois, United States
| |
Collapse
|
25
|
Pechauer AD, Tan O, Liu L, Jia Y, Hou V, Hills W, Huang D. Retinal Blood Flow Response to Hyperoxia Measured With En Face Doppler Optical Coherence Tomography. Invest Ophthalmol Vis Sci 2017; 57:OCT141-5. [PMID: 27409465 PMCID: PMC4968776 DOI: 10.1167/iovs.15-18917] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Purpose To use multiplane en face Doppler optical coherence tomography (OCT) to measure the change in total retinal blood flow (TRBF) in response to hyperoxia. Methods One eye of each healthy human participant (n = 8) was scanned with a commercial high-speed (70-kHz) spectral OCT system. Three repeated scans were captured at baseline and after 10 minutes of oxygen (hyperoxia) by open nasal mask. The procedure was performed twice on day 1 and once more on day 2. Blood flow of each vein was estimated using Doppler OCT at an optimized en face plane. The TRBF was summed from all veins at the optic disc. The TRBF hyperoxic response was calculated as the TRBF percent change from baseline. Results Participants experienced a 23.6% ± 10.7% (mean ± standard deviation [SD]) decrease (P < 0.001, paired t-test) in TRBF during hyperoxia. The within-day repeatability of baseline TRBF was 4.1% and the between-day reproducibility was 10.9% coefficient of variation (CV). Between-grader reproducibility was 3.9% CV. The repeatability and reproducibility (pooled SD) of hyperoxic response were 6.1% and 6.4%, respectively. Conclusions The multiplane en face Doppler OCT algorithm was able to detect, in all participants, a decreased TRBF in response to hyperoxia. The response magnitude for each participant varied among repeated trials, and the averaging of multiple trials was helpful in establishing the individual response. This technique shows good potential for the clinical investigation of vascular autoregulation.
Collapse
|
26
|
Pechauer AD, Hwang TS, Hagag AM, Liu L, Tan O, Zhang X, Parker M, Huang D, Wilson DJ, Jia Y. Assessing total retinal blood flow in diabetic retinopathy using multiplane en face Doppler optical coherence tomography. Br J Ophthalmol 2017; 102:126-130. [PMID: 28495904 DOI: 10.1136/bjophthalmol-2016-310042] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Revised: 04/19/2017] [Accepted: 04/23/2017] [Indexed: 01/05/2023]
Abstract
AIM To assess total retinal blood flow (TRBF) in diabetic retinopathy (DR) using multiplane en face Doppler optical coherence tomography (OCT). METHODS A 70 kHz spectral-domain OCT system scanned a 2×2 mm area centred at the optic disc of the eyes with DR and healthy participants. The multiplane en face Doppler OCT algorithm generated a three-dimensional volumetric data set consisting of 195 en face planes. The TRBF was calculated from the maximum flow values of each branching retinal vein at an optimised en face plane. DR severity was graded according to the international clinical classification system. The generalised linear model method was used to compare flow values between DR groups and the control group. RESULTS A total of 71 eyes from 71 participants were included. Ten eyes were excluded due to poor image quality. The within-visit repeatability of scans was 4.1% (coefficient of variation). There was no significant difference in the TRBF between the healthy (46.7±10.2 µL/min) and mild/moderate non-proliferative DR (44.9±12.6 µL/min) groups. The TRBF in severe non-proliferative DR (39.1±12.6 µL/min) and proliferative DR (28.9±8.85 µL/min) groups were significantly lower (p=0.04 and p<0.0001, respectively) than that of the healthy group. TRBF was correlated with DR disease severity (p<0.0001, linear trend test). CONCLUSION The novel multiplane en face Doppler OCT method provided reliable measurements of TRBF in DR eyes. This may be a useful tool in understanding the pathophysiology of DR.
Collapse
Affiliation(s)
- Alex D Pechauer
- Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, USA
| | - Thomas S Hwang
- Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, USA
| | - Ahmed M Hagag
- Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, USA
| | - Liang Liu
- Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, USA
| | - Ou Tan
- Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, USA
| | - Xinbo Zhang
- Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, USA
| | - Maria Parker
- Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, USA
| | - David Huang
- Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, USA
| | - David J Wilson
- Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, USA
| | - Yali Jia
- Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, USA
| |
Collapse
|
27
|
Chen C, Cheng KHY, Jakubovic R, Jivraj J, Ramjist J, Deorajh R, Gao W, Barnes E, Chin L, Yang VXD. High speed, wide velocity dynamic range Doppler optical coherence tomography (Part V): Optimal utilization of multi-beam scanning for Doppler and speckle variance microvascular imaging. OPTICS EXPRESS 2017; 25:7761-7777. [PMID: 28380895 DOI: 10.1364/oe.25.007761] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In this paper, a multi-beam scanning technique is proposed to optimize the microvascular images of human skin obtained with Doppler effect based methods and speckle variance processing. Flow phantom experiments were performed to investigate the suitability for combining multi-beam data to achieve enhanced microvascular imaging. To our surprise, the highly variable spot sizes (ranging from 13 to 77 μm) encountered in high numerical aperture multi-beam OCT system imaging the same target provided reasonably uniform Doppler variance and speckle variance responses as functions of flow velocity, which formed the basis for combining them to obtain better microvascular imaging without scanning penalty. In vivo 2D and 3D imaging of human skin was then performed to further demonstrate the benefit of combining multi-beam scanning to obtain improved signal-to-noise ratio (SNR) in microvascular imaging. Such SNR improvement can be as high as 10 dB. To our knowledge, this is the first demonstration of combining different spot size, staggered multiple optical foci scanning, to achieve enhanced SNR for blood flow OCT imaging.
Collapse
|
28
|
Nafar Z, Jiang M, Wen R, Jiao S. Visible-light optical coherence tomography-based multimodal retinal imaging for improvement of fluorescent intensity quantification. BIOMEDICAL OPTICS EXPRESS 2016; 7:3220-3229. [PMID: 27699094 PMCID: PMC5030006 DOI: 10.1364/boe.7.003220] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 07/31/2016] [Accepted: 07/31/2016] [Indexed: 05/03/2023]
Abstract
We developed a spectral-domain visible-light optical coherence tomography (VIS-OCT) based multimodal imaging technique which can accomplish simultaneous OCT and fluorescence imaging with a single broadband light source. Phantom experiments showed that by using the simultaneously acquired OCT images as a reference, the effect of light attenuation on the intensity of the fluorescent images by materials in front of the fluorescent target can be compensated. This capability of the multimodal imaging technique is of high importance for achieving quantification of the true intensities of autofluorescence (AF) imaging of the retina. We applied the technique in retinal imaging including AF imaging of the retinal pigment epithelium and fluorescein angiography (FA). We successfully demonstrated the effect of compensation on AF and FA images with the simultaneously acquired VIS-OCT images.
Collapse
Affiliation(s)
- Zahra Nafar
- Department of Biomedical Engineering, Florida International University, 10555 W Flagler ST, EC-2610, Miami, FL 33174, USA
| | - Minshan Jiang
- Department of Biomedical Engineering, Florida International University, 10555 W Flagler ST, EC-2610, Miami, FL 33174, USA
| | - Rong Wen
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, 1638 NW 10 Ave, Miami, FL 33136, USA
| | - Shuliang Jiao
- Department of Biomedical Engineering, Florida International University, 10555 W Flagler ST, EC-2610, Miami, FL 33174, USA
| |
Collapse
|
29
|
Mohindroo C, Ichhpujani P, Kumar S. Current Imaging Modalities for assessing Ocular Blood Flow in Glaucoma. J Curr Glaucoma Pract 2016; 10:104-112. [PMID: 27857490 PMCID: PMC5104970 DOI: 10.5005/jp-journals-10008-1210] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 06/12/2016] [Indexed: 11/29/2022] Open
Abstract
Glaucoma may be caused by an interplay of elevated intraocular pressure (IOP), vascular, genetic, anatomical, brain, and immune factors. The direct assessment of ocular hemodynam-ics offers promise for glaucoma detection, differentiation, and possibly new treatment modalities. All the methods currently in use to measure ocular blood flow have inherent limitations and measure different aspects of ocular blood flow. This review article attempts to provide detailed information on ocular perfu-sion pressure as well as an overview of the newly developed imaging technologies used to investigate ocular blood flow in glaucoma patients. HOW TO CITE THIS ARTICLE Mohindroo C, Ichhpujani P, Kumar S. Current Imaging Modalities for assessing Ocular Blood Flow in Glaucoma. J Curr Glaucoma Pract 2016;10(3):104-112.
Collapse
Affiliation(s)
- Chirayu Mohindroo
- Intern, Department of Ophthalmology, Government Medical College and Hospital, Chandigarh, India
| | - Parul Ichhpujani
- Associate Professor, Department of Ophthalmology, Government Medical College and Hospital, Chandigarh, India
| | - Suresh Kumar
- Professor, Department of Ophthalmology, Government Medical College and Hospital, Chandigarh, India
| |
Collapse
|
30
|
Uddin MI, Evans SM, Craft JR, Capozzi ME, McCollum GW, Yang R, Marnett LJ, Uddin MJ, Jayagopal A, Penn JS. In Vivo Imaging of Retinal Hypoxia in a Model of Oxygen-Induced Retinopathy. Sci Rep 2016; 6:31011. [PMID: 27491345 PMCID: PMC4974503 DOI: 10.1038/srep31011] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Accepted: 07/11/2016] [Indexed: 01/16/2023] Open
Abstract
Ischemia-induced hypoxia elicits retinal neovascularization and is a major component of several blinding retinopathies such as retinopathy of prematurity (ROP), diabetic retinopathy (DR) and retinal vein occlusion (RVO). Currently, noninvasive imaging techniques capable of detecting and monitoring retinal hypoxia in living systems do not exist. Such techniques would greatly clarify the role of hypoxia in experimental and human retinal neovascular pathogenesis. In this study, we developed and characterized HYPOX-4, a fluorescence-imaging probe capable of detecting retinal-hypoxia in living animals. HYPOX-4 dependent in vivo and ex vivo imaging of hypoxia was tested in a mouse model of oxygen-induced retinopathy (OIR). Predicted patterns of retinal hypoxia were imaged by HYPOX-4 dependent fluorescence activity in this animal model. In retinal cells and mouse retinal tissue, pimonidazole-adduct immunostaining confirmed the hypoxia selectivity of HYPOX-4. HYPOX-4 had no effect on retinal cell proliferation as indicated by BrdU assay and exhibited no acute toxicity in retinal tissue as indicated by TUNEL assay and electroretinography (ERG) analysis. Therefore, HYPOX-4 could potentially serve as the basis for in vivo fluorescence-based hypoxia-imaging techniques, providing a tool for investigators to understand the pathogenesis of ischemic retinopathies and for physicians to address unmet clinical needs.
Collapse
Affiliation(s)
- Md. Imam Uddin
- Department of Ophthalmology and Visual Sciences, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Stephanie M. Evans
- Department of Ophthalmology and Visual Sciences, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Jason R. Craft
- Department of Ophthalmology and Visual Sciences, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Megan E. Capozzi
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Gary W. McCollum
- Department of Ophthalmology and Visual Sciences, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Rong Yang
- Department of Ophthalmology and Visual Sciences, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Lawrence J. Marnett
- A. B. Hancock, Jr., Memorial Laboratory for Cancer Research, Departments of Biochemistry, Chemistry and Pharmacology, Vanderbilt Institute of Chemical Biology, Center for Molecular Toxicology and Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Md. Jashim Uddin
- A. B. Hancock, Jr., Memorial Laboratory for Cancer Research, Departments of Biochemistry, Chemistry and Pharmacology, Vanderbilt Institute of Chemical Biology, Center for Molecular Toxicology and Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Ashwath Jayagopal
- Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche, Ltd., Basel, Switzerland
| | - John S. Penn
- Department of Ophthalmology and Visual Sciences, Vanderbilt University School of Medicine, Nashville, TN, USA
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, USA
| |
Collapse
|
31
|
Liu W, Yi J, Chen S, Jiao S, Zhang HF. Measuring retinal blood flow in rats using Doppler optical coherence tomography without knowing eyeball axial length. Med Phys 2016; 42:5356-62. [PMID: 26328984 DOI: 10.1118/1.4928597] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Doppler optical coherence tomography (OCT) is widely used for measuring retinal blood flow. Existing Doppler OCT methods require the eyeball axial length, in which empirical values are usually used. However, variations in the axial length can create a bias unaccounted for in the retinal blood flow measurement. The authors plan to develop a Doppler OCT method that can measure the total retinal blood flow rate without requiring the eyeball axial length. METHODS The authors measured the retinal blood flow rate using a dual-ring scanning protocol. The small and large scanning rings entered the eye at different incident angles (small ring: 4°; large ring: 6°), focused on different locations on the retina, and detected the projected velocities/phase shifts along the probing beams. The authors calculated the ratio of the projected velocities between the two rings, and then used this ratio to estimate absolute flow velocity. The authors tested this method in both Intralipid phantoms and in vivo rats. RESULTS In the Intralipid flow phantom experiments, the preset and measured flow rates were consistent with the coefficient of determination as 0.97. Linear fitting between preset and measured flow rates determined the fitting slope as 1.07 and the intercept as -0.28. In in vivo rat experiments, the measured average total retinal blood flow was 7.02 ± 0.31 μl/min among four wild-type rats. The authors' measured flow rates were consistent with results in the literature. CONCLUSIONS By using a dual-ring scanning protocol with carefully controlled incident angle difference between the two scanning rings in Doppler OCT, the authors demonstrated that it is feasible to measure the absolute retinal blood flow without knowing the eyeball axial length.
Collapse
Affiliation(s)
- Wenzhong Liu
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois 60208
| | - Ji Yi
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois 60208
| | - Siyu Chen
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois 60208
| | - Shuliang Jiao
- Department of Biomedical Engineering, Florida International University, Miami, Florida 33174
| | - Hao F Zhang
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois 60208 and Department of Ophthalmology, Northwestern University, Chicago, Illinois 60611
| |
Collapse
|
32
|
Huang S, Shen M, Zhu D, Chen Q, Shi C, Chen Z, Lu F. In vivo imaging of retinal hemodynamics with OCT angiography and Doppler OCT. BIOMEDICAL OPTICS EXPRESS 2016; 7:663-76. [PMID: 26977370 PMCID: PMC4771479 DOI: 10.1364/boe.7.000663] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 01/20/2016] [Accepted: 01/20/2016] [Indexed: 05/08/2023]
Abstract
Retinal hemodynamics is important for early diagnosis and precise monitoring in retinal vascular diseases. We propose a novel method for measuring absolute retinal blood flow in vivo using the combined techniques of optical coherence tomography (OCT) angiography and Doppler OCT. Doppler values can be corrected by Doppler angles extracted from OCT angiography images. A three-dimensional (3D) segmentation algorithm based on dynamic programming was developed to extract the 3D boundaries of optic disc vessels, and Doppler angles were calculated from 3D vessel geometry. The accuracy of blood flow from the Doppler OCT was validated using a flow phantom. The feasibility of the method was tested on a subject in vivo. The pulsatile retinal blood flow and the parameters for retinal hemodynamics were successfully obtained.
Collapse
Affiliation(s)
- Shenghai Huang
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China
- Co-first authors: they have contributed equally to the project
| | - Meixiao Shen
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China
- Co-first authors: they have contributed equally to the project
| | - Dexi Zhu
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Qi Chen
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Ce Shi
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Zhongping Chen
- University of California, Irvine, Beckman Laser Institute, 1002 Health Sciences Road East, Irvine, California, USA
| | - Fan Lu
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China
| |
Collapse
|
33
|
Liu W, Zhang HF. Noninvasive in vivo imaging of oxygen metabolic rate in the retina. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2015; 2014:3865-8. [PMID: 25570835 DOI: 10.1109/embc.2014.6944467] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Precise and noninvasive measurement of retinal oxygen metabolic rate is important for retinal pathological investigations as well as retinal disease detection, which has not been achieved until recently. Here, we quantified retinal oxygen metabolic rate in rats by combining photoacoustic ophthalmoscopy with spectral domain-optical coherence tomography. We employed multi-wavelength photoacoustic ophthalmoscopy for oxygen saturation measurement and applied dual-ring scanning Doppler spectral domain-optical coherence tomography to image retinal blood flow. With retinal oxygen saturation and blood flow being measured, we determined the retinal oxygen metabolic rate in a typical rat to be 373.41 ± 88.04 ng/minute.
Collapse
|
34
|
Depth-resolved rhodopsin molecular contrast imaging for functional assessment of photoreceptors. Sci Rep 2015; 5:13992. [PMID: 26358529 PMCID: PMC4566094 DOI: 10.1038/srep13992] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Accepted: 08/13/2015] [Indexed: 11/08/2022] Open
Abstract
Rhodopsin, the light-sensing molecule in the outer segments of rod photoreceptors, is responsible for converting light into neuronal signals in a process known as phototransduction. Rhodopsin is thus a functional biomarker for rod photoreceptors. Here we report a novel technology based on visible-light optical coherence tomography (VIS-OCT) for in vivo molecular imaging of rhodopsin. The depth resolution of OCT allows the visualization of the location where the change of optical absorption occurs and provides a potentially accurate assessment of rhodopsin content by segmentation of the image at the location. Rhodopsin OCT can be used to quantitatively image rhodopsin distribution and thus assess the distribution of functional rod photoreceptors in the retina. Rhodopsin OCT can bring significant impact into ophthalmic clinics by providing a tool for the diagnosis and severity assessment of a variety of retinal conditions.
Collapse
|
35
|
Chen S, Yi J, Zhang HF. Measuring oxygen saturation in retinal and choroidal circulations in rats using visible light optical coherence tomography angiography. BIOMEDICAL OPTICS EXPRESS 2015; 6:2840-53. [PMID: 26309748 PMCID: PMC4541512 DOI: 10.1364/boe.6.002840] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Revised: 06/30/2015] [Accepted: 07/06/2015] [Indexed: 05/20/2023]
Abstract
Visible light optical coherence tomography (vis-OCT) has demonstrated its capability of measuring vascular oxygen saturation (sO2) in vivo. Enhanced by OCT angiography, the signal from microvasculature can be further isolated and directly used for sO2 extraction. In this work, we extended the theoretical formulation for OCT angiography-based oximetry by incorporating the contribution from motion contrast enhancement. We presented a new method to eliminate the associated confounding variables due to blood flow. First, we performed in vitro experiments to verify our theory, showing a stable spectral derivative within the selected wavelength bands for sO2 extraction. Then, we tested our method in vivo to measure retinal sO2 in rats inhaling different gas mixtures: normal air, 5% CO2, pure O2, and 10% O2. Absolute sO2 values in major arterioles and venules in the retinal circulation can be accurately measured. In addition, we demonstrated the relative changes of sO2 can be measured non-invasively from choriocapillaris immediately underneath the retinal pigmented epithelium (RPE) in rodents.
Collapse
Affiliation(s)
- Siyu Chen
- Department of Biomedical Engineering, Northwestern University, 2145 Sheridan Rd. Evanston, IL 60208 USA
- These authors contributed equally to this work
| | - Ji Yi
- Department of Biomedical Engineering, Northwestern University, 2145 Sheridan Rd. Evanston, IL 60208 USA
- These authors contributed equally to this work
| | - Hao F. Zhang
- Department of Biomedical Engineering, Northwestern University, 2145 Sheridan Rd. Evanston, IL 60208 USA
- Department of Ophthalmology, Northwestern University, 2145 Sheridan Rd., Evanston 60208, USA
| |
Collapse
|
36
|
Tan O, Liu G, Liang L, Gao SS, Pechauer AD, Jia Y, Huang D. En face Doppler total retinal blood flow measurement with 70 kHz spectral optical coherence tomography. JOURNAL OF BIOMEDICAL OPTICS 2015; 20:066004. [PMID: 26062663 PMCID: PMC4462711 DOI: 10.1117/1.jbo.20.6.066004] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Accepted: 05/14/2015] [Indexed: 05/03/2023]
Abstract
An automated algorithm was developed for total retinal blood flow (TRBF) using 70-kHz spectral optical coherence tomography (OCT). The OCT was calibrated for the transformation from Doppler shift to speed based on a flow phantom. The TRBF scan pattern contained five repeated volume scans (2 x 2 mm) obtained in 3 s and centered on central retinal vessels in the optic disc. The TRBF was calculated using an en face Doppler technique. For each retinal vein, blood flow was measured at an optimal plane where the calculated flow was maximized. The TRBF was calculated by summing flow in all veins. The algorithm tracked vascular branching so that either root or branch veins are summed, but never both. The TRBF in five repeated volumes were averaged to reduce variation due to cardiac cycle pulsation. Finally, the TRBF was corrected for eye length variation. Twelve healthy eyes and 12 glaucomatous eyes were enrolled to test the algorithm. The TRBF was 45.4 ± 6.7 μl/min for healthy control and 34.7 ± 7.6 μl/min for glaucomatous participants (p-value = 0.01). The intravisit repeatability was 8.6% for healthy controls and 8.4% for glaucoma participants. The proposed automated method provided repeatable TRBF measurement.
Collapse
Affiliation(s)
- Ou Tan
- Oregon Health and Science University, Casey Eye Institute, 3375 NW Terwilliger Boulevard, Portland, Oregon 97239, United States
- Address all correspondence to: Ou Tan, E-mail:
| | - Gangjun Liu
- Oregon Health and Science University, Casey Eye Institute, 3375 NW Terwilliger Boulevard, Portland, Oregon 97239, United States
| | - Liu Liang
- Oregon Health and Science University, Casey Eye Institute, 3375 NW Terwilliger Boulevard, Portland, Oregon 97239, United States
| | - Simon S. Gao
- Oregon Health and Science University, Casey Eye Institute, 3375 NW Terwilliger Boulevard, Portland, Oregon 97239, United States
| | - Alex D. Pechauer
- Oregon Health and Science University, Casey Eye Institute, 3375 NW Terwilliger Boulevard, Portland, Oregon 97239, United States
| | - Yali Jia
- Oregon Health and Science University, Casey Eye Institute, 3375 NW Terwilliger Boulevard, Portland, Oregon 97239, United States
| | - David Huang
- Oregon Health and Science University, Casey Eye Institute, 3375 NW Terwilliger Boulevard, Portland, Oregon 97239, United States
| |
Collapse
|
37
|
Poddar R, Zawadzki RJ, Cortés DE, Mannis MJ, Werner JS. In vivo volumetric depth-resolved vasculature imaging of human limbus and sclera with 1 μm swept source phase-variance optical coherence angiography. JOURNAL OF OPTICS (2010) 2015; 17:065301. [PMID: 25984290 PMCID: PMC4429254 DOI: 10.1088/2040-8978/17/6/065301] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We present nnnnnin vivo volumetric depth-resolved vasculature images of the anterior segment of the human eye acquired with phase-variance based motion contrast using a high-speed (100 kHz, 105 A-scans/s) swept source optical coherence tomography system (SSOCT). High phase stability SSOCT imaging was achieved by using a computationally efficient phase stabilization approach. The human corneo-scleral junction and sclera were imaged with swept source phase-variance optical coherence angiography and compared with slit lamp images from the same eyes of normal subjects. Different features of the rich vascular system in the conjunctiva and episclera were visualized and described. This system can be used as a potential tool for ophthalmological research to determine changes in the outflow system, which may be helpful for identification of abnormalities that lead to glaucoma.
Collapse
Affiliation(s)
- Raju Poddar
- Department of Bio-Engineering, Birla Institute of Technology-Mesra, Ranchi, JH 835 215, India
| | - Robert J Zawadzki
- Vision Science and Advanced Retinal Imaging Laboratory, Department of Ophthalmology and Vision Science, University of California Davis, Sacramento, CA 95817, USA
| | - Dennis E Cortés
- Vision Science and Advanced Retinal Imaging Laboratory, Department of Ophthalmology and Vision Science, University of California Davis, Sacramento, CA 95817, USA ; Department of Ophthalmology, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Mark J Mannis
- Vision Science and Advanced Retinal Imaging Laboratory, Department of Ophthalmology and Vision Science, University of California Davis, Sacramento, CA 95817, USA
| | - John S Werner
- Vision Science and Advanced Retinal Imaging Laboratory, Department of Ophthalmology and Vision Science, University of California Davis, Sacramento, CA 95817, USA
| |
Collapse
|
38
|
Aschinger GC, Schmetterer L, Doblhoff-Dier V, Leitgeb RA, Garhöfer G, Gröschl M, Werkmeister RM. Blood flow velocity vector field reconstruction from dual-beam bidirectional Doppler OCT measurements in retinal veins. BIOMEDICAL OPTICS EXPRESS 2015; 6:1599-615. [PMID: 26137367 PMCID: PMC4467707 DOI: 10.1364/boe.6.001599] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Revised: 03/06/2015] [Accepted: 03/06/2015] [Indexed: 05/21/2023]
Abstract
In this paper, we demonstrate the possibility to reconstruct the actual blood flow velocity vector field in retinal microvessels from dual-beam bidirectional Doppler optical coherence tomography measurements. First, for a better understanding of measured phase patterns, several flow situations were simulated on the basis of the known dual beam measurement geometry. We were able to extract the vector field parameters that determine the measured phase pattern, allowing for the development of an algorithm to reconstruct the velocity vector field from measured phase data. In a next step, measurements were performed at a straight vessel section and at a venous convergence; the obtained phase data were evaluated by means of the new approach. For the straight vessel section, the reconstructed flow velocity vector field yielded a parabolic flow. For the venous convergence, however, the reconstructed vector field deviated from a parabolic profile, but was in very good accordance with the simulated vector field for the given vessel geometry. The proposed algorithm allows predictions of the velocity vector field. Moreover, the algorithm is also sensitive to directional changes of the flow velocity as small as <1°, thereby offering insight in the flow characteristics of the non-Newtonian fluid blood in microvessels.
Collapse
Affiliation(s)
- Gerold C. Aschinger
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20/4L, A-1090 Vienna,
Austria
- Institute of Applied Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10, 1040 Vienna,
Austria
| | - Leopold Schmetterer
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20/4L, A-1090 Vienna,
Austria
- Department of Clinical Pharmacology, Medical University of Vienna, Waehringer Guertel 18-20/6L, A-1090 Vienna,
Austria
| | - Veronika Doblhoff-Dier
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20/4L, A-1090 Vienna,
Austria
- Institute of Applied Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10, 1040 Vienna,
Austria
| | - Rainer A. Leitgeb
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20/4L, A-1090 Vienna,
Austria
| | - Gerhard Garhöfer
- Department of Clinical Pharmacology, Medical University of Vienna, Waehringer Guertel 18-20/6L, A-1090 Vienna,
Austria
| | - Martin Gröschl
- Institute of Applied Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10, 1040 Vienna,
Austria
| | - René M. Werkmeister
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20/4L, A-1090 Vienna,
Austria
| |
Collapse
|
39
|
Uddin MI, Evans SM, Craft JR, Marnett LJ, Uddin MJ, Jayagopal A. Applications of azo-based probes for imaging retinal hypoxia. ACS Med Chem Lett 2015; 6:445-9. [PMID: 25893047 DOI: 10.1021/ml5005206] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Accepted: 02/12/2015] [Indexed: 11/29/2022] Open
Abstract
We report the design and synthesis of an activatable molecular imaging probe to detect hypoxia in mouse models of retinal vascular diseases. Hypoxia of the retina has been associated with the initiation and progression of blinding retinal vascular diseases including age-related macular degeneration, diabetic retinopathy, and retinopathy of prematurity. In vivo retinal imaging of hypoxia may be useful for early detection and timely treatment of retinal diseases. To achieve this goal, we synthesized HYPOX-3, a near-infrared (NIR) imaging agent coupled to a dark quencher, Black Hole Quencher 3 (BHQ3), which has been previously reported to contain a hypoxia-sensitive cleavable azo-bond. HYPOX-3 was cleaved in hypoxic retinal cell culture and animal models, enabling detection of hypoxia with high signal-to-noise ratios without acute toxicity. HYPOX-3 fluorescences in hypoxic cells and tissues and was undetectable under normoxia. These imaging agents are promising candidates for imaging retinal hypoxia in preclinical disease models and patients.
Collapse
Affiliation(s)
- Md. Imam Uddin
- Department
of Ophthalmology and Visual Sciences, Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, Tennessee 37232, United States
| | - Stephanie M. Evans
- Department
of Ophthalmology and Visual Sciences, Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, Tennessee 37232, United States
| | - Jason R. Craft
- Department
of Ophthalmology and Visual Sciences, Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, Tennessee 37232, United States
| | - Lawrence J. Marnett
- A. B.
Hancock, Jr., Memorial Laboratory for Cancer Research, Department
of Biochemistry, Chemistry and Pharmacology, Vanderbilt Institute
of Chemical Biology, Center for Molecular Toxicology and Vanderbilt-Ingram
Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
| | - Md. Jashim Uddin
- A. B.
Hancock, Jr., Memorial Laboratory for Cancer Research, Department
of Biochemistry, Chemistry and Pharmacology, Vanderbilt Institute
of Chemical Biology, Center for Molecular Toxicology and Vanderbilt-Ingram
Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
| | - Ashwath Jayagopal
- Department
of Ophthalmology and Visual Sciences, Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, Tennessee 37232, United States
- Molecular
Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
| |
Collapse
|
40
|
Evans SM, Kim K, Moore CE, Uddin MI, Capozzi ME, Craft JR, Sulikowski GA, Jayagopal A. Molecular probes for imaging of hypoxia in the retina. Bioconjug Chem 2014; 25:2030-7. [PMID: 25250692 PMCID: PMC4240343 DOI: 10.1021/bc500400z] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Hypoxia has been associated with retinal diseases which lead the causes of irreversible vision loss, including diabetic retinopathy, retinopathy of prematurity, and age-related macular degeneration. Therefore, technologies for imaging hypoxia in the retina are needed for early disease detection, monitoring of disease progression, and assessment of therapeutic responses in the patient. Toward this goal, we developed two hypoxia-sensitive imaging agents based on nitroimidazoles which are capable of accumulating in hypoxic cells in vivo. 2-nitroimidazole or Pimonidazole was conjugated to fluorescent dyes to yield the imaging agents HYPOX-1 and HYPOX-2. Imaging agents were characterized in cell culture and animal models of retinal vascular diseases which exhibit hypoxia. Both HYPOX-1 and -2 were capable of detecting hypoxia in cell culture models with >10:1 signal-to-noise ratios without acute toxicity. Furthermore, intraocular administration of contrast agents in mouse models of retinal hypoxia enabled ex vivo detection of hypoxic tissue. These imaging agents are a promising step toward translation of hypoxia-sensitive molecular imaging agents in preclinical animal models and patients.
Collapse
Affiliation(s)
- Stephanie M Evans
- Department of Ophthalmology and Visual Sciences, Vanderbilt Eye Institute , Nashville, Tennessee37232, United States
| | | | | | | | | | | | | | | |
Collapse
|
41
|
Song W, Wei Q, Liu W, Liu T, Yi J, Sheibani N, Fawzi AA, Linsenmeier RA, Jiao S, Zhang HF. A combined method to quantify the retinal metabolic rate of oxygen using photoacoustic ophthalmoscopy and optical coherence tomography. Sci Rep 2014; 4:6525. [PMID: 25283870 PMCID: PMC4185377 DOI: 10.1038/srep06525] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Accepted: 09/15/2014] [Indexed: 11/25/2022] Open
Abstract
Quantitatively determining physiological parameters at a microscopic level in the retina furthers the understanding of the molecular pathways of blinding diseases, such as diabetic retinopathy and glaucoma. An essential parameter, which has yet to be quantified noninvasively, is the retinal oxygen metabolic rate (rMRO2). Quantifying rMRO2 is challenging because two parameters, the blood flow rate and hemoglobin oxygen saturation (sO2), must be measured together. We combined photoacoustic ophthalmoscopy (PAOM) with spectral domain-optical coherence tomography (SD-OCT) to tackle this challenge, in which PAOM measured the sO2 and SD-OCT mapped the blood flow rate. We tested the integrated system on normal wild-type rats, in which the measured rMRO2 was 297.86 ± 70.23 nl/minute. This quantitative method may shed new light on both fundamental research and clinical care in ophthalmology in the future.
Collapse
Affiliation(s)
- Wei Song
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
- Department of Physics, Harbin Institute of Technology, 92 West Da-Zhi Street Nangang District, Harbin, Heilongjiang 150080, China
- These authors contributed equally to this work
| | - Qing Wei
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
- These authors contributed equally to this work
| | - Wenzhong Liu
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
- These authors contributed equally to this work
| | - Tan Liu
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Ji Yi
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Nader Sheibani
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, WI 53792, USA
| | - Amani A. Fawzi
- Department of Ophthalmology, Northwestern University, Chicago, IL 60611, USA
| | - Robert A. Linsenmeier
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
- Department of Ophthalmology, Northwestern University, Chicago, IL 60611, USA
- Department of Neurobiology and Physiology, Northwestern University, Evanston, IL 60208, USA
| | - Shuliang Jiao
- Department of Biomedical Engineering, Florida International University, Miami, FL 33174, USA
| | - Hao F. Zhang
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
- Department of Ophthalmology, Northwestern University, Chicago, IL 60611, USA
| |
Collapse
|
42
|
Palkovits S, Told R, Schmidl D, Boltz A, Napora KJ, Lasta M, Kaya S, Werkmeister RM, Popa-Cherecheanu A, Garhöfer G, Schmetterer L. Regulation of retinal oxygen metabolism in humans during graded hypoxia. Am J Physiol Heart Circ Physiol 2014; 307:H1412-8. [PMID: 25217648 DOI: 10.1152/ajpheart.00479.2014] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Animal experiments indicate that the inner retina keeps its oxygen extraction constant despite systemic hypoxia. For the human retina no such data exist. In the present study we hypothesized that systemic hypoxia does not alter inner retinal oxygen extraction. To test this hypothesis we included 30 healthy male and female subjects aged between 18 and 35 years. All subjects were studied at baseline and during breathing 12% O₂ in 88% N₂ as well as breathing 15% O₂ in 85% N₂. Oxygen saturation in a retinal artery (SO₂art) and an adjacent retinal vein (SO₂vein) were measured using spectroscopic fundus reflectometry. Measurements of retinal venous blood velocity using bidirectional laser Doppler velocimetry and retinal venous diameters using a Retinal Vessel Analyzer (RVA) were combined to calculate retinal blood flow. Oxygen and carbon dioxide partial pressure were measured from earlobe arterialized capillary blood. Retinal blood flow was increased by 43.0 ± 23.2% (P < 0.001) and 30.0 ± 20.9% (P < 0.001) during 12% and 15% O₂ breathing, respectively. SO₂art as well as SO₂vein decreased during both 12% O₂ breathing (SO₂art: -11.2 ± 4.3%, P < 0.001; SO₂vein: -3.9 ± 8.5%, P = 0.012) and 15% O₂ breathing (SO₂art: -7.9 ± 3.6%, P < 0.001; SO₂vein: -4.0 ± 7.0%, P = 0.010). The arteriovenous oxygen difference decreased during both breathing periods (12% O2: -28.9 ± 18.7%; 15% O₂: -19.1 ± 16.7%, P < 0.001 each). Calculated oxygen extraction did, however, not change during our experiments (12% O₂: -2.8 ± 18.9%, P = 0.65; 15% O₂: 2.4 ± 15.8%, P = 0.26). Our results indicate that in healthy humans, oxygen extraction of the inner retina remains constant during systemic hypoxia.
Collapse
Affiliation(s)
- Stefan Palkovits
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Reinhard Told
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria; Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria; and
| | - Doreen Schmidl
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria; Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria; and
| | - Agnes Boltz
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria; Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria; and
| | - Katarzyna J Napora
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Michael Lasta
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Semira Kaya
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
| | - René M Werkmeister
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria; and
| | | | - Gerhard Garhöfer
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Leopold Schmetterer
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria; Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria; and
| |
Collapse
|
43
|
Shahidi AM, Patel SR, Huang D, Tan O, Flanagan JG, Hudson C. Assessment of total retinal blood flow using Doppler Fourier Domain Optical Coherence Tomography during systemic hypercapnia and hypocapnia. Physiol Rep 2014; 2:2/7/e12046. [PMID: 25038117 PMCID: PMC4187559 DOI: 10.14814/phy2.12046] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
The purpose of this study was to investigate changes in total retinal blood flow (RBF) using Doppler Fourier Domain Optical Coherence Tomography (Doppler FD‐OCT) in response to the manipulation of systemic partial pressure of CO2 (PETCO2). Double circular Doppler blood flow scans were captured in nine healthy individuals (mean age ± standard deviation: 27.1 ± 4.1, six males) using the RTVue™ FD‐OCT (Optovue). PETCO2 was manipulated using a custom‐designed computer‐controlled gas blender (RespirAct™) connected to a sequential gas delivery rebreathing circuit. Doppler FD‐OCT measurements were captured at baseline, during stages of hypercapnia (+5/+10/+15 mmHg PETCO2), return to baseline and during stages of hypocapnia (−5/−10/−15 mmHg PETCO2). Repeated measures analysis of variance (reANOVA) and Tukey's post hoc analysis were used to compare Doppler FD‐OCT measurements between the various PETCO2 levels relative to baseline. The effect of PETCO2 on TRBF was also investigated using linear regression models. The average RBF significantly increased by 15% (P < 0.0001) with an increase in PETCO2 and decreased significantly by 10% with a decrease in PETCO2 (P = 0.001). Venous velocity significantly increased by 3.11% from baseline to extreme hypercapnia (P < 0.001) and reduced significantly by 2.01% at extreme hypocapnia (P = 0.012). No significant changes were found in the average venous area measurements under hypercapnia (P = 0.36) or hypocapnia (P = 0.40). Overall, increased and decreased PETCO2 values had a significant effect on RBF outcomes (P < 0.002). In healthy individuals, altered end‐tidal CO2 levels significantly changed RBF as measured by Doppler FD‐OCT. Total retinal blood flow changes in response to the manipulation of systemic partial pressure of CO2 was measured in healthy individuals using Doppler Fourier Domain Optical Coherence Tomography. Increased total retinal blood flow and decreased blood flow were found in response to hypercapnia and hypocapnia, respectively.
Collapse
Affiliation(s)
- Ayda M Shahidi
- Department of Ophthalmology and Vision Science, Toronto Western Research Institute, Toronto, Ontario, Canada School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada
| | - Sunni R Patel
- Department of Ophthalmology and Vision Science, Toronto Western Research Institute, Toronto, Ontario, Canada
| | - David Huang
- Oregon Health & Science University, Portland, Oregon
| | - Ou Tan
- Oregon Health & Science University, Portland, Oregon
| | - John G Flanagan
- Department of Ophthalmology and Vision Science, Toronto Western Research Institute, Toronto, Ontario, Canada School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada
| | - Chris Hudson
- Department of Ophthalmology and Vision Science, Toronto Western Research Institute, Toronto, Ontario, Canada School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada
| |
Collapse
|
44
|
Abstract
Gender medicine has been a major focus of research in recent years. The present review focuses on gender differences in the epidemiology of the most frequent ocular diseases that have been found to be associated with impaired ocular blood flow, such as age-related macular degeneration, glaucoma and diabetic retinopathy. Data have accumulated indicating that hormones have an important role in these diseases, since there are major differences in the prevalence and incidence between men and pre- and post-menopausal women. Whether this is related to vascular factors is, however, not entirely clear. Interestingly, the current knowledge about differences in ocular vascular parameters between men and women is sparse. Although little data is available, estrogen, progesterone and testosterone are most likely important regulators of blood flow in the retina and choroid, because they are key regulators of vascular tone in other organs. Estrogen seems to play a protective role since it decreases vascular resistance in large ocular vessels. Some studies indicate that hormone therapy is beneficial for ocular vascular disease in post-menopausal women. This evidence is, however, not sufficient to give any recommendation. Generally, remarkably few data are available on the role of sex hormones on ocular blood flow regulation, a topic that requires more attention in the future.
Collapse
Affiliation(s)
- Doreen Schmidl
- Department of Clinical Pharmacology, Medical University of Vienna , Vienna , Austria
| | | | | | | |
Collapse
|
45
|
Nan N, Wang X, Bu P, Li Z, Guo X, Chen Y, Wang X, Yuan F, Sasaki O. Full-range Fourier domain Doppler optical coherence tomography based on sinusoidal phase modulation. APPLIED OPTICS 2014; 53:2669-2676. [PMID: 24787594 DOI: 10.1364/ao.53.002669] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Accepted: 03/16/2014] [Indexed: 06/03/2023]
Abstract
A novel full-range Fourier domain Doppler optical coherence tomography (full-range FD-DOCT) using sinusoidal phase modulation for B-M scan is proposed. In this sinusoidal B-M scan, zero optical path difference (OPD) position does not move corresponding to lateral scanning points in contrast to linear B-M scan. Since high phase sensitivity arises around the zero OPD position, the proposed full-range FD-DOCT can achieve easily high velocity sensitivity without mirror image around the zero OPD position. Velocity sensitivity dependent on the OPD and the interval of scanning points is examined, and flow velocity detection capability is verified through Doppler imaging of a flow phantom and an in vivo biological sample.
Collapse
|
46
|
Leitgeb RA, Werkmeister RM, Blatter C, Schmetterer L. Doppler optical coherence tomography. Prog Retin Eye Res 2014; 41:26-43. [PMID: 24704352 PMCID: PMC4073226 DOI: 10.1016/j.preteyeres.2014.03.004] [Citation(s) in RCA: 227] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2014] [Revised: 03/21/2014] [Accepted: 03/26/2014] [Indexed: 11/19/2022]
Abstract
Optical Coherence Tomography (OCT) has revolutionized ophthalmology. Since its introduction in the early 1990s it has continuously improved in terms of speed, resolution and sensitivity. The technique has also seen a variety of extensions aiming to assess functional aspects of the tissue in addition to morphology. One of these approaches is Doppler OCT (DOCT), which aims to visualize and quantify blood flow. Such extensions were already implemented in time domain systems, but have gained importance with the introduction of Fourier domain OCT. Nowadays phase-sensitive detection techniques are most widely used to extract blood velocity and blood flow from tissues. A common problem with the technique is that the Doppler angle is not known and several approaches have been realized to obtain absolute velocity and flow data from the retina. Additional studies are required to elucidate which of these techniques is most promising. In the recent years, however, several groups have shown that data can be obtained with high validity and reproducibility. In addition, several groups have published values for total retinal blood flow. Another promising application relates to non-invasive angiography. As compared to standard techniques such as fluorescein and indocyanine-green angiography the technique offers two major advantages: no dye is required and depth resolution is required is provided. As such Doppler OCT has the potential to improve our abilities to diagnose and monitor ocular vascular diseases.
Collapse
Affiliation(s)
- Rainer A Leitgeb
- Center for Medical Physics and Biomedical Engineering, Medical University Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
| | - René M Werkmeister
- Center for Medical Physics and Biomedical Engineering, Medical University Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
| | - Cedric Blatter
- Center for Medical Physics and Biomedical Engineering, Medical University Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
| | - Leopold Schmetterer
- Center for Medical Physics and Biomedical Engineering, Medical University Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria; Department of Clinical Pharmacology, Medical University Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria.
| |
Collapse
|