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Linsenmeier RA, Dmitriev AV, Dmitriev AA. Oxygen profiles and oxygen consumption in the isolated mouse retina. Exp Eye Res 2023; 233:109554. [PMID: 37437835 PMCID: PMC10528762 DOI: 10.1016/j.exer.2023.109554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Revised: 06/14/2023] [Accepted: 06/23/2023] [Indexed: 07/14/2023]
Abstract
The retina has a large demand for oxygen, but there is only limited information on differences between oxygen utilization (QO2) in the inner and outer retina, and limited data on mouse, which has become a prevalent animal model. This study utilized the isolated mouse retina, which allowed more detailed spatial analysis of QO2 than other methods. Oxygen sensitive microelectrodes were used to obtain profiles of oxygen tension across the isolated mouse retina, and mathematical models of retinal oxygen diffusion with four and five layers were fitted to the data to obtain values for QO2 of the outer retina (QOR) and inner retina (QIR). The boundaries between layers were free parameters in these models. The five-layer model resulted in lower error between the model and data, and agreed better with known anatomy. The three layers for the outer retina occupied half of the retina, as in prior work on rat, cat, and monkey, and the inner half of the retina could be divided into two layers, in which the one closer to the vitreous (layer 5) had much lower QO2 than the more distal inner retina (layer 4). QIR in darkness was 3.9 ml O2-100 g-1-min-1, similar to the value for intact cat retina, and did not change during light. QOR in darkness was 2.4 ml O2-100 g-1-min-1, lower than previous values in cat and rat, possibly because of damage to photoreceptors during isolation. There was a tendency for QOR to be lower in light, but it was not significant in this preparation.
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Affiliation(s)
- Robert A Linsenmeier
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, USA; Department of Neurobiology, Northwestern University, Evanston, Illinois, USA; Department of Ophthalmology, Northwestern University, Chicago, Illinois, USA.
| | - Andrey V Dmitriev
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, USA.
| | - Alexander A Dmitriev
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, USA.
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2
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Mitamura M, Kase S, Hirooka K, Ishida S. A case of choroidal melanocytosis observed by multimodal imaging with laser speckle flowgraphy. BMC Ophthalmol 2023; 23:180. [PMID: 37101259 PMCID: PMC10131401 DOI: 10.1186/s12886-023-02933-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 04/21/2023] [Indexed: 04/28/2023] Open
Abstract
BACKGROUND Choroidal melanocytosis is characterized by congenital diffuse melanin pigmentation with extensive parenchymal infiltration of spindle cells in the choroid; however, little is known about the choroidal circulation and morphological changes. We herein report a case of choroidal melanocytosis observed by multimodal imaging with laser speckle flowgraphy (LSFG). CASE PRESENTATION A 56-year-old woman was referred to our hospital because of serous retinal detachment (SRD) in her left eye. At the initial examination, her best-corrected visual acuity (BCVA) was 1.5 oculus dexter (OD) and 0.8 oculus sinister (OS). An irregular, flat, brownish lesion was noted around the macula OS. Optical coherence tomography showed a choroidal structure with marked hyporeflectivity and SRD where the retinal thickness was preserved. Indocyanine green angiography demonstrated fluorescence blockade throughout. Fundus autofluorescence revealed enlarged macular hypofluorescence, suggesting chronic retinal pigment epithelium damage associated with prolonged SRD. B-mode echography showed no choroidal elevation. Based on the clinical findings, the left eye was diagnosed with choroidal melanocytosis. Four years and 10 months after the initial visit, her BCVA was 0.5 and SRD remained. During the entire period of observation, the mean blur rate (MBR) (mean ± standard deviation) of choroidal blood flow velocity on LSFG was 10.15 ± 0.72 arbitrary units (AU) OD and 1.31 ± 0.06 AU OS. CONCLUSION Choroidal melanocytosis presented with chronic minor circulatory disturbances due to melanocyte proliferation in the choroid, but the markedly low MBR values by LSFG were dissociated from her retinal thickness and visual function. The proliferation of melanocytes may be a cause of overestimating the cold-color signal of LSFG due to their pigmentation.
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Affiliation(s)
- Mizuho Mitamura
- Department of Ophthalmology, Faculty of Medicine, Graduate School of Medicine, Hokkaido University, N-15, W-7, Kita-ku, Sapporo, 060-8638, Japan
| | - Satoru Kase
- Department of Ophthalmology, Faculty of Medicine, Graduate School of Medicine, Hokkaido University, N-15, W-7, Kita-ku, Sapporo, 060-8638, Japan.
| | - Kiriko Hirooka
- Department of Ophthalmology, Faculty of Medicine, Graduate School of Medicine, Hokkaido University, N-15, W-7, Kita-ku, Sapporo, 060-8638, Japan
| | - Susumu Ishida
- Department of Ophthalmology, Faculty of Medicine, Graduate School of Medicine, Hokkaido University, N-15, W-7, Kita-ku, Sapporo, 060-8638, Japan
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3
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Fang R, Rubinoff I, Zhang HF. Multiple forward scattering reduces the measured scattering coefficient of whole blood in visible-light optical coherence tomography. BIOMEDICAL OPTICS EXPRESS 2022; 13:4510-4527. [PMID: 36187273 PMCID: PMC9484418 DOI: 10.1364/boe.459607] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 07/18/2022] [Accepted: 07/19/2022] [Indexed: 05/10/2023]
Abstract
The optical properties of blood encode oxygen-dependent information. Noninvasive optical detection of these properties is increasingly desirable to extract biomarkers for tissue health. Recently, visible-light optical coherence tomography (vis-OCT) demonstrated retinal oxygen saturation (sO2) measurements by inversely measuring the oxygen-dependent absorption and scattering coefficients of whole blood. However, vis-OCT may be sensitive to optical scattering properties of whole blood, different from those reported in the literature. Incorrect assumptions of such properties can add additional uncertainties or biases to vis-OCT's sO2 model. This work investigates whole blood's scattering coefficient measured by vis-OCT. Using Monte Carlo simulation of a retinal vessel, we determined that vis-OCT almost exclusively detects multiple-scattered photons in whole blood. Meanwhile, photons mostly forward scatter in whole blood within the visible spectral range, allowing photons to maintain ballistic paths and penetrate deeply, leading to a reduction in the measured scattering coefficient. We defined a scattering scaling factor (SSF) to account for such a reduction and found that SSF varied with measurement conditions, such as numerical aperture, depth resolution, and depth selection. We further experimentally validated SSF in ex vivo blood phantoms with pre-set sO2 levels and in the human retina, both of which agreed well with our simulation.
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Affiliation(s)
- Raymond Fang
- Department of Biomedical Engineering, Northwestern University, Evanston IL 60208, USA
- These authors contributed equally to this work
| | - Ian Rubinoff
- Department of Biomedical Engineering, Northwestern University, Evanston IL 60208, USA
- These authors contributed equally to this work
| | - Hao F. Zhang
- Department of Biomedical Engineering, Northwestern University, Evanston IL 60208, USA
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Taylor-Williams M, Spicer G, Bale G, Bohndiek SE. Noninvasive hemoglobin sensing and imaging: optical tools for disease diagnosis. JOURNAL OF BIOMEDICAL OPTICS 2022; 27:JBO-220074VR. [PMID: 35922891 PMCID: PMC9346606 DOI: 10.1117/1.jbo.27.8.080901] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 06/27/2022] [Indexed: 05/08/2023]
Abstract
SIGNIFICANCE Measurement and imaging of hemoglobin oxygenation are used extensively in the detection and diagnosis of disease; however, the applied instruments vary widely in their depth of imaging, spatiotemporal resolution, sensitivity, accuracy, complexity, physical size, and cost. The wide variation in available instrumentation can make it challenging for end users to select the appropriate tools for their application and to understand the relative limitations of different methods. AIM We aim to provide a systematic overview of the field of hemoglobin imaging and sensing. APPROACH We reviewed the sensing and imaging methods used to analyze hemoglobin oxygenation, including pulse oximetry, spectral reflectance imaging, diffuse optical imaging, spectroscopic optical coherence tomography, photoacoustic imaging, and diffuse correlation spectroscopy. RESULTS We compared and contrasted the ability of different methods to determine hemoglobin biomarkers such as oxygenation while considering factors that influence their practical application. CONCLUSIONS We highlight key limitations in the current state-of-the-art and make suggestions for routes to advance the clinical use and interpretation of hemoglobin oxygenation information.
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Affiliation(s)
- Michaela Taylor-Williams
- University of Cambridge, Department of Physics, Cavendish Laboratory, Cambridge, United Kingdom, United Kingdom
- University of Cambridge, Cancer Research UK Cambridge Institute, Cambridge, United Kingdom, United Kingdom
| | - Graham Spicer
- University of Cambridge, Department of Physics, Cavendish Laboratory, Cambridge, United Kingdom, United Kingdom
- University of Cambridge, Cancer Research UK Cambridge Institute, Cambridge, United Kingdom, United Kingdom
| | - Gemma Bale
- University of Cambridge, Department of Physics, Cavendish Laboratory, Cambridge, United Kingdom, United Kingdom
- University of Cambridge, Electrical Division, Department of Engineering, Cambridge, United Kingdom, United Kingdom
| | - Sarah E Bohndiek
- University of Cambridge, Department of Physics, Cavendish Laboratory, Cambridge, United Kingdom, United Kingdom
- University of Cambridge, Cancer Research UK Cambridge Institute, Cambridge, United Kingdom, United Kingdom
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5
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Alexopoulos P, Madu C, Wollstein G, Schuman JS. The Development and Clinical Application of Innovative Optical Ophthalmic Imaging Techniques. Front Med (Lausanne) 2022; 9:891369. [PMID: 35847772 PMCID: PMC9279625 DOI: 10.3389/fmed.2022.891369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 05/23/2022] [Indexed: 11/22/2022] Open
Abstract
The field of ophthalmic imaging has grown substantially over the last years. Massive improvements in image processing and computer hardware have allowed the emergence of multiple imaging techniques of the eye that can transform patient care. The purpose of this review is to describe the most recent advances in eye imaging and explain how new technologies and imaging methods can be utilized in a clinical setting. The introduction of optical coherence tomography (OCT) was a revolution in eye imaging and has since become the standard of care for a plethora of conditions. Its most recent iterations, OCT angiography, and visible light OCT, as well as imaging modalities, such as fluorescent lifetime imaging ophthalmoscopy, would allow a more thorough evaluation of patients and provide additional information on disease processes. Toward that goal, the application of adaptive optics (AO) and full-field scanning to a variety of eye imaging techniques has further allowed the histologic study of single cells in the retina and anterior segment. Toward the goal of remote eye care and more accessible eye imaging, methods such as handheld OCT devices and imaging through smartphones, have emerged. Finally, incorporating artificial intelligence (AI) in eye images has the potential to become a new milestone for eye imaging while also contributing in social aspects of eye care.
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Affiliation(s)
- Palaiologos Alexopoulos
- Department of Ophthalmology, NYU Langone Health, NYU Grossman School of Medicine, New York, NY, United States
| | - Chisom Madu
- Department of Ophthalmology, NYU Langone Health, NYU Grossman School of Medicine, New York, NY, United States
| | - Gadi Wollstein
- Department of Ophthalmology, NYU Langone Health, NYU Grossman School of Medicine, New York, NY, United States
- Department of Biomedical Engineering, NYU Tandon School of Engineering, Brooklyn, NY, United States
- Center for Neural Science, College of Arts & Science, New York University, New York, NY, United States
| | - Joel S. Schuman
- Department of Ophthalmology, NYU Langone Health, NYU Grossman School of Medicine, New York, NY, United States
- Department of Biomedical Engineering, NYU Tandon School of Engineering, Brooklyn, NY, United States
- Center for Neural Science, College of Arts & Science, New York University, New York, NY, United States
- Department of Electrical and Computer Engineering, NYU Tandon School of Engineering, Brooklyn, NY, United States
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6
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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: 5] [Impact Index Per Article: 2.5] [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.
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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
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7
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Retinal blood flow dysregulation precedes neural retinal dysfunction in type 2 diabetic mice. Sci Rep 2021; 11:18401. [PMID: 34526573 PMCID: PMC8443656 DOI: 10.1038/s41598-021-97651-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Accepted: 08/27/2021] [Indexed: 11/23/2022] Open
Abstract
We investigated and compared the susceptibility of retinal blood flow regulation and neural function in mice developing type 2 diabetes. The longitudinal changes in retinal neuronal function and blood flow responses to a 10-min systemic hyperoxia and a 3-min flicker stimulation were evaluated every 2 weeks in diabetic db/db mice and nondiabetic controls (db/m) from age 8 to 20 weeks. The retinal blood flow and neural activity were assessed using laser speckle flowgraphy and electroretinography (ERG), respectively. The db/db mice had significantly higher blood glucose levels and body weight. The resting retinal blood flow was steady and comparable between two groups throughout the study. Hyperoxia elicited a consistent decrease, and flicker light an increase, in retinal blood flow in db/m mice independent of age. However, these flow responses were significantly diminished in db/db mice at 8 weeks old and then the mice became unresponsive to stimulations at 12 weeks. Subsequently, the ERG implicit time for oscillatory potential was significantly increased at 14 weeks of age while the a-wave and b-wave amplitudes and implicit times remained unchanged. The deficiencies of flow regulation and neurovascular coupling in the retina appear to precede neural dysfunction in the mouse with type 2 diabetes.
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8
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Li Y, Li B, Wang B, Liu M, Zhang X, Li A, Zhang J, Zhang H, Xiu R. Integrated pancreatic microcirculatory profiles of streptozotocin-induced and insulin-administrated type 1 diabetes mellitus. Microcirculation 2021; 28:e12691. [PMID: 33655585 PMCID: PMC8365673 DOI: 10.1111/micc.12691] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 02/17/2021] [Accepted: 02/24/2021] [Indexed: 12/12/2022]
Abstract
OBJECTIVE As an integrated system, pancreatic microcirculatory disturbance plays a vital role in the pathogenesis of type 1 diabetes mellitus (T1DM), which involves changes in microcirculatory oxygen and microhemodynamics. Therefore, we aimed to release type 1 diabetic and insulin-administrated microcirculatory profiles of the pancreas. METHODS BALB/c mice were assigned to control, T1DM, and insulin-administrated groups randomly. T1DM was induced by intraperitoneal injection of streptozotocin (STZ). 1.5 IU insulin was administrated subcutaneously to keep the blood glucose within the normal range. After anesthetizing by isoflurane, the raw data set of pancreatic microcirculation was collected by the multimodal device- and computer algorithm-based microcirculatory evaluating system. After adjusting outliers and normalization, pancreatic microcirculatory oxygen and microhemodynamic data sets were imported into the three-dimensional module and compared. RESULTS Microcirculatory profiles of the pancreas in T1DM exhibited a loss of microhemodynamic coherence (significantly decreased microvascular blood perfusion) accompanied by an impaired oxygen balance (significantly decreased PO2 , SO2 , and rHb). More importantly, with insulin administration, the pathological microcirculatory profiles were partially restored. Meanwhile, there were correlations between pancreatic microcirculatory blood perfusion and PO2 levels. CONCLUSIONS Our findings establish the first integrated three-dimensional pancreatic microcirculatory profiles of STZ-induced and insulin-administrated T1DM.
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Affiliation(s)
- Yuan Li
- Institute of Microcirculation, Key Laboratory of Microcirculation, Ministry of Health, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Bingwei Li
- Institute of Microcirculation, Key Laboratory of Microcirculation, Ministry of Health, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Bing Wang
- Institute of Microcirculation, Key Laboratory of Microcirculation, Ministry of Health, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Mingming Liu
- Institute of Microcirculation, Key Laboratory of Microcirculation, Ministry of Health, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China.,Diabetes Research Center, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Xiaoyan Zhang
- Institute of Microcirculation, Key Laboratory of Microcirculation, Ministry of Health, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Ailing Li
- Institute of Microcirculation, Key Laboratory of Microcirculation, Ministry of Health, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Jian Zhang
- Institute of Microcirculation, Key Laboratory of Microcirculation, Ministry of Health, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China.,Diabetes Research Center, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Honggang Zhang
- Institute of Microcirculation, Key Laboratory of Microcirculation, Ministry of Health, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Ruijuan Xiu
- Institute of Microcirculation, Key Laboratory of Microcirculation, Ministry of Health, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
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9
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Abstract
Vision loss, among the most feared complications of diabetes, is primarily caused by diabetic retinopathy, a disease that manifests in well-recognized, characteristic microvascular lesions. The reasons for retinal susceptibility to damage in diabetes are unclear, especially considering that microvascular networks are found in all tissues. However, the unique metabolic demands of retinal neurons could account for their vulnerability in diabetes. Photoreceptors are the first neurons in the visual circuit and are also the most energy-demanding cells of the retina. Here, we review experimental and clinical evidence linking photoreceptors to the development of diabetic retinopathy. We then describe the influence of retinal illumination on photoreceptor metabolism, effects of light modulation on the severity of diabetic retinopathy, and recent clinical trials testing the treatment of diabetic retinopathy with interventions that impact photoreceptor metabolism. Finally, we introduce several possible mechanisms that could link photoreceptor responses to light and the development of retinal vascular disease in diabetes. Collectively, these concepts form the basis for a growing body of investigative efforts aimed at developing novel pharmacologic and nonpharmacologic tools that target photoreceptor physiology to treat a very common cause of blindness across the world.
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10
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Liu R, Cheng S, Tian L, Yi J. Deep spectral learning for label-free optical imaging oximetry with uncertainty quantification. LIGHT, SCIENCE & APPLICATIONS 2019; 8:102. [PMID: 31754429 PMCID: PMC6864044 DOI: 10.1038/s41377-019-0216-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 10/17/2019] [Accepted: 11/01/2019] [Indexed: 05/06/2023]
Abstract
Measurement of blood oxygen saturation (sO2) by optical imaging oximetry provides invaluable insight into local tissue functions and metabolism. Despite different embodiments and modalities, all label-free optical-imaging oximetry techniques utilize the same principle of sO2-dependent spectral contrast from haemoglobin. Traditional approaches for quantifying sO2 often rely on analytical models that are fitted by the spectral measurements. These approaches in practice suffer from uncertainties due to biological variability, tissue geometry, light scattering, systemic spectral bias, and variations in the experimental conditions. Here, we propose a new data-driven approach, termed deep spectral learning (DSL), to achieve oximetry that is highly robust to experimental variations and, more importantly, able to provide uncertainty quantification for each sO2 prediction. To demonstrate the robustness and generalizability of DSL, we analyse data from two visible light optical coherence tomography (vis-OCT) setups across two separate in vivo experiments on rat retinas. Predictions made by DSL are highly adaptive to experimental variabilities as well as the depth-dependent backscattering spectra. Two neural-network-based models are tested and compared with the traditional least-squares fitting (LSF) method. The DSL-predicted sO2 shows significantly lower mean-square errors than those of the LSF. For the first time, we have demonstrated en face maps of retinal oximetry along with a pixel-wise confidence assessment. Our DSL overcomes several limitations of traditional approaches and provides a more flexible, robust, and reliable deep learning approach for in vivo non-invasive label-free optical oximetry.
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Affiliation(s)
- Rongrong Liu
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208 USA
| | - Shiyi Cheng
- Department of Electrical and Computer Engineering, Boston University, Boston, MA 02215 USA
| | - Lei Tian
- Department of Electrical and Computer Engineering, Boston University, Boston, MA 02215 USA
| | - Ji Yi
- Department of Electrical and Computer Engineering, Boston University, Boston, MA 02215 USA
- Department of Biomedical Engineering, Boston University, Boston, MA 02215 USA
- Department of Medicine, Boston University School of Medicine, Boston Medical Center, Boston, MA 02118 USA
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11
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Pi S, Hormel TT, Wei X, Cepurna W, Camino A, Guo Y, Huang D, Morrison J, Jia Y. Monitoring retinal responses to acute intraocular pressure elevation in rats with visible light optical coherence tomography. NEUROPHOTONICS 2019; 6:041104. [PMID: 31312671 PMCID: PMC6624745 DOI: 10.1117/1.nph.6.4.041104] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Accepted: 06/21/2019] [Indexed: 05/08/2023]
Abstract
Elevated intraocular pressure (IOP) is an important risk factor for glaucoma. However, the role of IOP in glaucoma progression, as well as retinal physiology in general, remains incompletely understood. We demonstrate the use of visible light optical coherence tomography to measure retinal responses to acute IOP elevation in Brown Norway rats. We monitored retinal responses in reflectivity, angiography, blood flow, oxygen saturation ( sO 2 ), and oxygen metabolism over a range of IOP from 10 to 100 mmHg. As IOP was elevated, nerve fiber layer reflectivity was found to decrease. Vascular perfusion in the three retinal capillary plexuses remained steady until IOP exceeded 70 mmHg and arterial flow was noted to reverse periodically at high IOPs. However, a significant drop in total retinal blood flow was observed first at 40 mmHg. As IOP increased, the venous sO 2 demonstrated a gradual decrease despite steady arterial sO 2 , which is consistent with increased arterial-venous oxygen extraction across the retinal capillary beds. Calculated total retinal oxygen metabolism was steady, reflecting balanced responses of blood flow and oxygen extraction, until IOP exceeded 40 mmHg, and fell to 0 at 70 and 80 mmHg. Above this, measurements were unattainable. All measurements reverted to baseline when the IOP was returned to 10 mmHg, indicating good recovery following acute pressure challenge. These results demonstrate the ability of this system to monitor retinal oxygen metabolism noninvasively and how it can help us understand retinal responses to elevated IOP.
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Affiliation(s)
- Shaohua Pi
- Oregon Health and Science University, Casey Eye Institute, Portland, Oregon, United States
| | - Tristan T. Hormel
- Oregon Health and Science University, Casey Eye Institute, Portland, Oregon, United States
| | - Xiang Wei
- Oregon Health and Science University, Casey Eye Institute, Portland, Oregon, United States
| | - William Cepurna
- Oregon Health and Science University, Casey Eye Institute, Portland, Oregon, United States
| | - Acner Camino
- Oregon Health and Science University, Casey Eye Institute, Portland, Oregon, United States
| | - Yukun Guo
- Oregon Health and Science University, Casey Eye Institute, Portland, Oregon, United States
| | - David Huang
- Oregon Health and Science University, Casey Eye Institute, Portland, Oregon, United States
| | - John Morrison
- Oregon Health and Science University, Casey Eye Institute, Portland, Oregon, United States
| | - Yali Jia
- Oregon Health and Science University, Casey Eye Institute, Portland, Oregon, United States
- Address all correspondence to Yali Jia, E-mail:
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12
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Beckmann L, Zhang X, Nadkarni NA, Cai Z, Batra A, Sullivan DP, Muller WA, Sun C, Kuranov R, Zhang HF. Longitudinal deep-brain imaging in mouse using visible-light optical coherence tomography through chronic microprism cranial window. BIOMEDICAL OPTICS EXPRESS 2019; 10:5235-5250. [PMID: 31646044 PMCID: PMC6788609 DOI: 10.1364/boe.10.005235] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 09/10/2019] [Accepted: 09/10/2019] [Indexed: 05/02/2023]
Abstract
We longitudinally imaged both the superficial and deep cortical microvascular networks in brains of healthy mice and in a mouse model of stroke in vivo using visible-light optical coherence tomography (vis-OCT). We surgically implanted a microprism in mouse brains sealed by a chronic cranial window. The microprism enabled vis-OCT to image the entire depth of the mouse cortex. Following microprism implantation, we imaged the mice for 28 days and found that that it took around 15 days for both the superficial and deep cortical microvessels to recover from the implantation surgery. After the brains recovered, we introduced ischemic strokes by transient middle cerebral artery occlusion (tMCAO). We monitored the strokes for up to 60 days and observed different microvascular responses to tMCAO at different cortical depths in both the acute and chronic phases of the stroke. This work demonstrates that the combined microprism and cranial window is well-suited for longitudinal investigation of cortical microvascular disorders using vis-OCT.
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Affiliation(s)
- Lisa Beckmann
- Department of Biomedical Engineering, Northwestern University, Evanston IL 60208, USA
- These authors contributed equally to this work
| | - Xian Zhang
- Department of Biomedical Engineering, Northwestern University, Evanston IL 60208, USA
- Department of Ophthalmology, Tongji Hospital, Tongji Medical College, HuaZhong University of Science and Technology, Wuhan, Hubei, China
- These authors contributed equally to this work
| | - Neil A. Nadkarni
- Department of Neurology, Northwestern University, Chicago IL 60611, USA
| | - Zhen Cai
- Department of Biomedical Engineering, Northwestern University, Evanston IL 60208, USA
- Department of Ophthalmology, Tongji Hospital, Tongji Medical College, HuaZhong University of Science and Technology, Wuhan, Hubei, China
| | - Ayush Batra
- Department of Neurology, Northwestern University, Chicago IL 60611, USA
| | - David P. Sullivan
- Department of Pathology, Northwestern University, Chicago IL 60611, USA
| | - William A. Muller
- Department of Pathology, Northwestern University, Chicago IL 60611, USA
| | - Cheng Sun
- Department of Mechanical Engineering, Northwestern University, Evanston IL 60208, USA
| | - Roman Kuranov
- Department of Biomedical Engineering, Northwestern University, Evanston IL 60208, USA
- Opticent Health, Evanston IL, Evanston IL 60201, USA
| | - Hao F. Zhang
- Department of Biomedical Engineering, Northwestern University, Evanston IL 60208, USA
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13
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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.
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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
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14
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Feng W, Liu S, Zhang C, Xia Q, Yu T, Zhu D. Comparison of cerebral and cutaneous microvascular dysfunction with the development of type 1 diabetes. Theranostics 2019; 9:5854-5868. [PMID: 31534524 PMCID: PMC6735377 DOI: 10.7150/thno.33738] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Accepted: 06/19/2019] [Indexed: 02/07/2023] Open
Abstract
Rationale: Diabetes can lead to cerebral and cutaneous vascular dysfunction. However, it is still unclear how vascular function changes with the development of diabetes and what differences exist between cerebral and cutaneous vascular dysfunction. Thus, it is very important to monitor changes in cerebral and cutaneous vascular function responses in vivo and study their differences during diabetes development. Methods: With the assistance of newly developed skull and skin optical clearing techniques, we monitored the responses of sodium nitroprusside (SNP)- and acetyl choline (ACh)-induced cerebral and cutaneous vascular blood flow and blood oxygen in diabetic mice in vivo during the development of type 1 diabetes (T1D) by combining laser speckle contrast imaging with hyperspectral imaging. We then compared the differences between cerebral and cutaneous vascular responses and explored the reasons for abnormal changes induced in response to different vascular beds. Results: In the early stage of diabetes (T1D-1 week), there were abnormal changes in the cerebral vascular blood flow and blood oxygen responses to SNP and ACh as well as cutaneous vascular blood oxygen. The cutaneous vascular blood flow response also became abnormal from T1D-3 weeks. Additionally, the T1D-induced abnormal blood flow response was associated with changes in vascular myosin light chain phosphorylation and muscarinic acetylcholine receptor M3 levels, and the aberrant blood oxygen response was related to an increase in glycated hemoglobin levels. Conclusion: These results suggest that the abnormal cutaneous vascular blood oxygen response occurred earlier than the blood flow response and therefore has the potential to serve as a good assessment indicator for revealing cerebrovascular dysfunction in the early stage of diabetes.
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Affiliation(s)
- Wei Feng
- Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics-Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
- MoE Key Laboratory for Biomedical Photonics, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Shaojun Liu
- Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics-Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
- MoE Key Laboratory for Biomedical Photonics, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Chao Zhang
- Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics-Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
- MoE Key Laboratory for Biomedical Photonics, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Qing Xia
- Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics-Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
- MoE Key Laboratory for Biomedical Photonics, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Tingting Yu
- Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics-Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
- MoE Key Laboratory for Biomedical Photonics, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Dan Zhu
- Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics-Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
- MoE Key Laboratory for Biomedical Photonics, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
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15
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Joseph A, Guevara-Torres A, Schallek J. Imaging single-cell blood flow in the smallest to largest vessels in the living retina. eLife 2019; 8:45077. [PMID: 31084705 PMCID: PMC6516827 DOI: 10.7554/elife.45077] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 04/15/2019] [Indexed: 01/15/2023] Open
Abstract
Tissue light scatter limits the visualization of the microvascular network deep inside the living mammal. The transparency of the mammalian eye provides a noninvasive view of the microvessels of the retina, a part of the central nervous system. Despite its clarity, imperfections in the optics of the eye blur microscopic retinal capillaries, and single blood cells flowing within. This limits early evaluation of microvascular diseases that originate in capillaries. To break this barrier, we use 15 kHz adaptive optics imaging to noninvasively measure single-cell blood flow, in one of the most widely used research animals: the C57BL/6J mouse. Measured flow ranged four orders of magnitude (0.0002-1.55 µL min-1) across the full spectrum of retinal vessel diameters (3.2-45.8 µm), without requiring surgery or contrast dye. Here, we describe the ultrafast imaging, analysis pipeline and automated measurement of millions of blood cell speeds.
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Affiliation(s)
- Aby Joseph
- Institute of Optics, University of Rochester, New York, United States.,Center for Visual Science, University of Rochester, New York, United States
| | - Andres Guevara-Torres
- Institute of Optics, University of Rochester, New York, United States.,Center for Visual Science, University of Rochester, New York, United States
| | - Jesse Schallek
- Center for Visual Science, University of Rochester, New York, United States.,Flaum Eye Institute, University of Rochester, New York, United States.,Department of Neuroscience, University of Rochester, New York, United States
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16
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Shu X, Beckmann L, Wang Y, Rubinoff I, Lucy K, Ishikawa H, Wollstein G, Fawzi AA, Schuman JS, Kuranov RV, Zhang HF. Designing visible-light optical coherence tomography towards clinics. Quant Imaging Med Surg 2019; 9:769-781. [PMID: 31281773 PMCID: PMC6571199 DOI: 10.21037/qims.2019.05.01] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 05/04/2019] [Indexed: 12/31/2022]
Abstract
BACKGROUND The capabilities of visible-light optical coherence tomography (vis-OCT) in noninvasive anatomical and functional retinal imaging have been demonstrated by multiple groups in both rodents and healthy human subjects. Translating laboratory prototypes to an integrated clinical-environment-friendly system is required to explore the full potential of vis-OCT in disease management. METHODS We developed and optimized a portable vis-OCT system for human retinal imaging in clinical settings. We acquired raster- and circular-scan images from both healthy and diseased human eyes. RESULTS The new vis-OCT provided high-quality retinal images of both subjects without any known eye diseases and patients with various retinal diseases, including retinal occlusive disease and diabetic retinopathy (DR) over a broad range of ages. CONCLUSIONS A newly designed vis-OCT system is sufficiently optimized to be suited for routine patients' examinations in clinics. Vis-OCT has the potential to add new anatomical and functional imaging capabilities to ophthalmic clinical care.
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Affiliation(s)
- Xiao Shu
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, USA
| | - Lisa Beckmann
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, USA
| | | | - Ian Rubinoff
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, USA
| | - Katie Lucy
- NYU Langone Eye Center, NYU School of Medicine, New York, NY, USA
| | - Hiroshi Ishikawa
- NYU Langone Eye Center, NYU School of Medicine, New York, NY, USA
| | - Gadi Wollstein
- NYU Langone Eye Center, NYU School of Medicine, New York, NY, USA
| | - Amani A. Fawzi
- Department of Ophthalmology, Northwestern University, Chicago, IL, USA
| | - Joel S. Schuman
- NYU Langone Eye Center, NYU School of Medicine, New York, NY, USA
| | - Roman V. Kuranov
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, USA
- Opticent Health, Evanston, IL, USA
| | - Hao F. Zhang
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, USA
- Department of Ophthalmology, Northwestern University, Chicago, IL, USA
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17
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Early detection of diabetic retinopathy. Surv Ophthalmol 2018; 63:601-608. [DOI: 10.1016/j.survophthal.2018.04.003] [Citation(s) in RCA: 79] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2017] [Revised: 04/07/2018] [Accepted: 04/09/2018] [Indexed: 12/15/2022]
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18
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Soetikno BT, Beckmann L, Zhang X, Fawzi AA, Zhang HF. Visible-light optical coherence tomography oximetry based on circumpapillary scan and graph-search segmentation. BIOMEDICAL OPTICS EXPRESS 2018; 9:3640-3652. [PMID: 30338145 PMCID: PMC6191632 DOI: 10.1364/boe.9.003640] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Revised: 06/25/2018] [Accepted: 06/25/2018] [Indexed: 05/18/2023]
Abstract
Visible-light optical coherence tomography (vis-OCT) enables retinal oximetry by measuring the oxygen saturation of hemoglobin (sO2) from within individual retinal blood vessels. The sO2 calculation requires reliable estimation of the true spectrum of backscattered light from the posterior vessel wall. Unfortunately, subject motion and image noise make averaging from multiple A-lines at the same depth position challenging, and lead to inaccurate sO2 estimation. In this study, we developed an algorithm to reliably extract the backscattered light's spectrum. We used circumpapillary scanning to sample the vessels repeatedly at the same location. A combination of cross-correlation and graph-search based segmentation extracted the posterior wall locations. Using measurements from 100 B-scans as a gold standard, we demonstrated that our method achieved highly accurate measures of sO2 with minimal bias. In addition, we also investigated how the number of repeated measurements affects the accuracy of sO2 measurement. Our method sets the stage for large-scale studies of retinal oxygenation in animals and humans.
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Affiliation(s)
- Brian T. Soetikno
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, USA
- Department of Ophthalmology, Northwestern University, Chicago, IL, USA
- Medical Scientist Training Program, Northwestern University, Chicago, IL, USA
| | - Lisa Beckmann
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, USA
| | - Xian Zhang
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, USA
| | - Amani A. Fawzi
- Department of Ophthalmology, Northwestern University, Chicago, IL, USA
| | - Hao F. Zhang
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, USA
- Department of Ophthalmology, Northwestern University, Chicago, IL, USA
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19
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Harper DJ, Augustin M, Lichtenegger A, Eugui P, Reyes C, Glösmann M, Hitzenberger CK, Baumann B. White light polarization sensitive optical coherence tomography for sub-micron axial resolution and spectroscopic contrast in the murine retina. BIOMEDICAL OPTICS EXPRESS 2018; 9:2115-2129. [PMID: 29760974 PMCID: PMC5946775 DOI: 10.1364/boe.9.002115] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 03/29/2018] [Accepted: 03/30/2018] [Indexed: 05/03/2023]
Abstract
A white light polarization sensitive optical coherence tomography system has been developed, using a supercontinuum laser as the light source. By detecting backscattered light from 400 - 700 nm, an axial resolution of 1.0 µm in air was achieved. The system consists of a free-space interferometer and two homemade spectrometers that detect orthogonal polarization states. Following system specifications, images of a healthy murine retina as acquired by this non-contact system are presented, showing high resolution reflectivity images as well as spectroscopic and polarization sensitive contrast. Additional images of the very-low-density-lipoprotein-receptor (VLDLR) knockout mouse model were acquired. The high resolution allows the detection of small lesions in the retina.
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Affiliation(s)
- Danielle J. Harper
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20/4L, 1090 Vienna,
Austria
| | - Marco Augustin
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20/4L, 1090 Vienna,
Austria
| | - Antonia Lichtenegger
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20/4L, 1090 Vienna,
Austria
| | - Pablo Eugui
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20/4L, 1090 Vienna,
Austria
| | - Carlos Reyes
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20/4L, 1090 Vienna,
Austria
| | - Martin Glösmann
- University of Veterinary Medicine Vienna, Core Facility for Research and Technology, Veterinaerplatz 1, 1210 Vienna,
Austria
| | - Christoph K. Hitzenberger
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20/4L, 1090 Vienna,
Austria
| | - Bernhard Baumann
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20/4L, 1090 Vienna,
Austria
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20
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Shu X, Beckmann L, Zhang HF. Visible-light optical coherence tomography: a review. JOURNAL OF BIOMEDICAL OPTICS 2017; 22:1-14. [PMID: 29218923 PMCID: PMC5745673 DOI: 10.1117/1.jbo.22.12.121707] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Accepted: 11/13/2017] [Indexed: 05/03/2023]
Abstract
Visible-light optical coherence tomography (vis-OCT) is an emerging imaging modality, providing new capabilities in both anatomical and functional imaging of biological tissue. It relies on visible light illumination, whereas most commercial and investigational OCTs use near-infrared light. As a result, vis-OCT requires different considerations in engineering design and implementation but brings unique potential benefits to both fundamental research and clinical care of several diseases. Here, we intend to provide a summary of the development of vis-OCT and its demonstrated applications. We also provide perspectives on future technology improvement and applications.
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Affiliation(s)
- Xiao Shu
- Northwestern University, Department of Biomedical Engineering, Evanston, Illinois, United States
| | - Lisa Beckmann
- Northwestern University, Department of Biomedical Engineering, Evanston, Illinois, United States
| | - Hao F. Zhang
- Northwestern University, Department of Biomedical Engineering, Evanston, Illinois, United States
- Northwestern University, Department of Ophthalmology, Chicago, Illinois, United States
- Address all correspondence to: Hao F. Zhang, E-mail:
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21
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Shu X, Liu W, Duan L, Zhang HF. Spectroscopic Doppler analysis for visible-light optical coherence tomography. JOURNAL OF BIOMEDICAL OPTICS 2017; 22:1-8. [PMID: 29043714 PMCID: PMC5644441 DOI: 10.1117/1.jbo.22.12.121702] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Accepted: 08/18/2017] [Indexed: 05/20/2023]
Abstract
Retinal oxygen metabolic rate can be effectively measured by visible-light optical coherence tomography (vis-OCT), which simultaneously quantifies oxygen saturation and blood flow rate in retinal vessels through spectroscopic analysis and Doppler measurement, respectively. Doppler OCT relates phase variation between sequential A-lines to the axial flow velocity of the scattering medium. The detectable phase shift is between -π and π due to its periodicity, which limits the maximum measurable unambiguous velocity without phase unwrapping. Using shorter wavelengths, vis-OCT is more vulnerable to phase ambiguity since flow induced phase variation is linearly related to the center wavenumber of the probing light. We eliminated the need for phase unwrapping using spectroscopic Doppler analysis. We split the whole vis-OCT spectrum into a series of narrow subbands and reconstructed vis-OCT images to extract corresponding Doppler phase shifts in all the subbands. Then, we quantified flow velocity by analyzing subband-dependent phase shift using linear regression. In the phantom experiment, we showed that spectroscopic Doppler analysis extended the measurable absolute phase shift range without conducting phase unwrapping. We also tested this method to quantify retinal blood flow in rodents in vivo.
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Affiliation(s)
- Xiao Shu
- Northwestern University, Department of Biomedical Engineering, Evanston, Illinois, United States
| | - Wenzhong Liu
- Opticent Health, Evanston, Illinois, United States
| | - Lian Duan
- Northwestern University, Department of Biomedical Engineering, Evanston, Illinois, United States
| | - Hao F. Zhang
- Northwestern University, Department of Biomedical Engineering, Evanston, Illinois, United States
- Northwestern University, Department of Ophthalmology, Chicago, Illinois, United States
- Address all correspondence to: Hao F. Zhang, E-mail:
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22
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Chen S, Shu X, Nesper PL, Liu W, Fawzi AA, Zhang HF. Retinal oximetry in humans using visible-light optical coherence tomography [Invited]. BIOMEDICAL OPTICS EXPRESS 2017; 8:1415-1429. [PMID: 28663838 PMCID: PMC5480553 DOI: 10.1364/boe.8.001415] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Revised: 02/01/2017] [Accepted: 02/01/2017] [Indexed: 05/18/2023]
Abstract
We measured hemoglobin oxygen saturation (sO2) in the retinal circulation in healthy humans using visible-light optical coherence tomography (vis-OCT). The measurements showed clear oxygenation differences between central retinal arteries and veins close to the optic nerve head. Spatial variations at different vascular branching levels were also revealed. In addition, we presented theoretical and experimental results to establish that noises in OCT intensity followed Rice distribution. We used this knowledge to retrieve unbiased estimation of true OCT intensity to improve the accuracy of vis-OCT oximetry, which had inherently lower signal-to-nose ratio from human eyes due to safety and comfort limitations. We demonstrated that the new statistical-fitting sampling strategy could reduce the estimation error in sO2 by three percentage points (pp). The presented work aims to provide a foundation for using vis-OCT to achieve accurate retinal oximetry in clinical settings.
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Affiliation(s)
- Siyu Chen
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Xiao Shu
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Peter L. Nesper
- Department of Ophthalmology, Northwestern University, Chicago, IL 60611, USA
| | - Wenzhong Liu
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
- Currently with Opticent Health, Evanston, IL 60208, USA
| | - Amani A. Fawzi
- Department of Ophthalmology, Northwestern University, Chicago, IL 60611, USA
| | - Hao F. Zhang
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
- Department of Ophthalmology, Northwestern University, Chicago, IL 60611, USA
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