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Iyer RR, Žurauskas M, Rao Y, Chaney EJ, Boppart SA. Bichromatic tetraphasic full-field optical coherence microscopy. JOURNAL OF BIOMEDICAL OPTICS 2024; 29:S22704. [PMID: 38584966 PMCID: PMC10996847 DOI: 10.1117/1.jbo.29.s2.s22704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Revised: 02/29/2024] [Accepted: 03/05/2024] [Indexed: 04/09/2024]
Abstract
Significance Full-field optical coherence microscopy (FF-OCM) is a prevalent technique for backscattering and phase imaging with epi-detection. Traditional methods have two limitations: suboptimal utilization of functional information about the sample and complicated optical design with several moving parts for phase contrast. Aim We report an OCM setup capable of generating dynamic intensity, phase, and pseudo-spectroscopic contrast with single-shot full-field video-rate imaging called bichromatic tetraphasic (BiTe) full-field OCM with no moving parts. Approach BiTe OCM resourcefully uses the phase-shifting properties of anti-reflection (AR) coatings outside the rated bandwidths to create four unique phase shifts, which are detected with two emission filters for spectroscopic contrast. Results BiTe OCM overcomes the disadvantages of previous FF-OCM setup techniques by capturing both the intensity and phase profiles without any artifacts or speckle noise for imaging scattering samples in three-dimensional (3D). BiTe OCM also utilizes the raw data effectively to generate three complementary contrasts: intensity, phase, and color. We demonstrate BiTe OCM to observe cellular dynamics, image live, and moving micro-animals in 3D, capture the spectroscopic hemodynamics of scattering tissues along with dynamic intensity and phase profiles, and image the microstructure of fall foliage with two different colors. Conclusions BiTe OCM can maximize the information efficiency of FF-OCM while maintaining overall simplicity in design for quantitative, dynamic, and spectroscopic characterization of biological samples.
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Affiliation(s)
- Rishyashring R. Iyer
- University of Illinois Urbana-Champaign, Beckman Institute for Advanced Science and Technology, Urbana, Illinois, United States
- University of Illinois Urbana-Champaign, Department of Electrical and Computer Engineering, Urbana, Illinois, United States
| | - Mantas Žurauskas
- University of Illinois Urbana-Champaign, Beckman Institute for Advanced Science and Technology, Urbana, Illinois, United States
| | - Yug Rao
- University of Illinois Urbana-Champaign, Beckman Institute for Advanced Science and Technology, Urbana, Illinois, United States
- University of Illinois Urbana-Champaign, Department of Electrical and Computer Engineering, Urbana, Illinois, United States
| | - Eric J. Chaney
- University of Illinois Urbana-Champaign, Beckman Institute for Advanced Science and Technology, Urbana, Illinois, United States
| | - Stephen A. Boppart
- University of Illinois Urbana-Champaign, Beckman Institute for Advanced Science and Technology, Urbana, Illinois, United States
- University of Illinois Urbana-Champaign, Department of Electrical and Computer Engineering, Urbana, Illinois, United States
- University of Illinois Urbana-Champaign, Department of Bioengineering, Urbana, Illinois, United States
- University of Illinois Urbana Champaign, NIH/NIBIB P41 Center for Label-free Imaging and Multiscale Biophotonics (CLIMB), Urbana, Illinois, United States
- University of Illinois Urbana-Champaign, Cancer Center at Illinois, Urbana, Illinois, United States
- University of Illinois Urbana-Champaign, Carle Illinois College of Medicine, Urbana, Illinois, United States
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2
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Marshall AG, Neikirk K, Afolabi J, Mwesigwa N, Shao B, Kirabo A, Reddy AK, Hinton A. Update on the Use of Pulse Wave Velocity to Measure Age-Related Vascular Changes. Curr Hypertens Rep 2024; 26:131-140. [PMID: 38159167 PMCID: PMC10955453 DOI: 10.1007/s11906-023-01285-x] [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] [Accepted: 11/08/2023] [Indexed: 01/03/2024]
Abstract
PURPOSE OF REVIEW Pulse wave velocity (PWV) is an important and well-established measure of arterial stiffness that is strongly associated with aging. Age-related alterations in the elastic properties and integrity of arterial walls can lead to cardiovascular disease. PWV measurements play an important role in the early detection of these changes, as well as other cardiovascular disease risk factors, such as hypertension. This review provides a comprehensive summary of the current knowledge of the effects of aging on arterial stiffness, as measured by PWV. RECENT FINDINGS This review highlights recent findings showing the applicability of PWV analysis for investigating heart failure, hypertension, and other cardiovascular diseases, as well as cerebrovascular diseases and Alzheimer's disease. It also discusses the clinical implications of utilizing PWV to monitor treatment outcomes, various challenges in implementing PWV assessment in clinical practice, and the development of new technologies, including machine learning and artificial intelligence, which may improve the usefulness of PWV measurements in the future. Measuring arterial stiffness through PWV remains an important technique to study aging, especially as the technology continues to evolve. There is a clear need to leverage PWV to identify interventions that mitigate age-related increases in PWV, potentially improving CVD outcomes and promoting healthy vascular aging.
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Affiliation(s)
- Andrea G Marshall
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA
| | - Kit Neikirk
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA
| | - Jeremiah Afolabi
- Department of Medicine, Vanderbilt University Medical Center, 750 Robinson Research Building, 2200 Pierce Ave, Nashville, TN, 37232-0615, USA
| | - Naome Mwesigwa
- Department of Medicine, Vanderbilt University Medical Center, 750 Robinson Research Building, 2200 Pierce Ave, Nashville, TN, 37232-0615, USA
| | - Bryanna Shao
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA
| | - Annet Kirabo
- Department of Medicine, Vanderbilt University Medical Center, 750 Robinson Research Building, 2200 Pierce Ave, Nashville, TN, 37232-0615, USA
| | - Anilkumar K Reddy
- Department of Medicine, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA
| | - Antentor Hinton
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA.
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3
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Pian Q, Alfadhel M, Tang J, Lee GV, Li B, Fu B, Ayata Y, Yaseen MA, Boas DA, Secomb TW, Sakadzic S. Cortical microvascular blood flow velocity mapping by combining dynamic light scattering optical coherence tomography and two-photon microscopy. JOURNAL OF BIOMEDICAL OPTICS 2023; 28:076003. [PMID: 37484973 PMCID: PMC10362155 DOI: 10.1117/1.jbo.28.7.076003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Revised: 05/30/2023] [Accepted: 06/05/2023] [Indexed: 07/25/2023]
Abstract
Significance The accurate large-scale mapping of cerebral microvascular blood flow velocity is crucial for a better understanding of cerebral blood flow (CBF) regulation. Although optical imaging techniques enable both high-resolution microvascular angiography and fast absolute CBF velocity measurements in the mouse cortex, they usually require different imaging techniques with independent system configurations to maximize their performances. Consequently, it is still a challenge to accurately combine functional and morphological measurements to co-register CBF speed distribution from hundreds of microvessels with high-resolution microvascular angiograms. Aim We propose a data acquisition and processing framework to co-register a large set of microvascular blood flow velocity measurements from dynamic light scattering optical coherence tomography (DLS-OCT) with the corresponding microvascular angiogram obtained using two-photon microscopy (2PM). Approach We used DLS-OCT to first rapidly acquire a large set of microvascular velocities through a sealed cranial window in mice and then to acquire high-resolution microvascular angiograms using 2PM. The acquired data were processed in three steps: (i) 2PM angiogram coregistration with the DLS-OCT angiogram, (ii) 2PM angiogram segmentation and graphing, and (iii) mapping of the CBF velocities to the graph representation of the 2PM angiogram. Results We implemented the developed framework on the three datasets acquired from the mice cortices to facilitate the coregistration of the large sets of DLS-OCT flow velocity measurements with 2PM angiograms. We retrieved the distributions of red blood cell velocities in arterioles, venules, and capillaries as a function of the branching order from precapillary arterioles and postcapillary venules from more than 1000 microvascular segments. Conclusions The proposed framework may serve as a useful tool for quantitative analysis of large microvascular datasets obtained by OCT and 2PM in studies involving normal brain functioning, progression of various diseases, and numerical modeling of the oxygen advection and diffusion in the realistic microvascular networks.
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Affiliation(s)
- Qi Pian
- Massachusetts General Hospital, Harvard Medical School, Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Charlestown, Massachusetts, United States
| | - Mohammed Alfadhel
- Massachusetts General Hospital, Harvard Medical School, Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Charlestown, Massachusetts, United States
- Northeastern University, Department of Bioengineering, Boston, Massachusetts, United States
| | - Jianbo Tang
- Southern University of Science and Technology, Department of Biomedical Engineering, Shenzhen, China
| | - Grace V. Lee
- University of Arizona, Program in Applied Mathematics, Tucson, Arizona, United States
| | - Baoqiang Li
- Massachusetts General Hospital, Harvard Medical School, Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Charlestown, Massachusetts, United States
- Chinese Academy of Sciences, Shenzhen Institute of Advanced Technology, Brain Cognition and Brain Disease Institute; Shenzhen Fundamental Research Institutions, Shenzhen–Hong Kong Institute of Brain Science, Shenzhen, Guangdong, China
| | - Buyin Fu
- Massachusetts General Hospital, Harvard Medical School, Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Charlestown, Massachusetts, United States
| | - Yagmur Ayata
- Massachusetts General Hospital, Harvard Medical School, Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Charlestown, Massachusetts, United States
| | - Mohammad Abbas Yaseen
- Massachusetts General Hospital, Harvard Medical School, Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Charlestown, Massachusetts, United States
- Northeastern University, Department of Bioengineering, Boston, Massachusetts, United States
| | - David A. Boas
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
| | - Timothy W. Secomb
- University of Arizona, Program in Applied Mathematics, Tucson, Arizona, United States
- University of Arizona, Department of Mathematics, Tucson, Arizona, United States
- University of Arizona, Department of Physiology, Tucson, Arizona, United States
| | - Sava Sakadzic
- Massachusetts General Hospital, Harvard Medical School, Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Charlestown, Massachusetts, United States
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Li B, Yabluchanskiy A, Tarantini S, Allu SR, Şencan-Eğilmez I, Leng J, Alfadhel MAH, Porter JE, Fu B, Ran C, Erdener SE, Boas DA, Vinogradov SA, Sonntag WE, Csiszar A, Ungvari Z, Sakadžić S. Measurements of cerebral microvascular blood flow, oxygenation, and morphology in a mouse model of whole-brain irradiation-induced cognitive impairment by two-photon microscopy and optical coherence tomography: evidence for microvascular injury in the cerebral white matter. GeroScience 2023; 45:1491-1510. [PMID: 36792820 PMCID: PMC10400746 DOI: 10.1007/s11357-023-00735-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Accepted: 01/17/2023] [Indexed: 02/17/2023] Open
Abstract
Whole-brain irradiation (WBI, also known as whole-brain radiation therapy) is a mainstay treatment modality for patients with multiple brain metastases. It is also used as a prophylactic treatment for microscopic tumors that cannot be detected by magnetic resonance imaging. WBI induces a progressive cognitive decline in ~ 50% of the patients surviving over 6 months, significantly compromising the quality of life. There is increasing preclinical evidence that radiation-induced injury to the cerebral microvasculature and accelerated neurovascular senescence plays a central role in this side effect of WBI. To better understand this side effect, male C57BL/6 mice were first subjected to a clinically relevant protocol of fractionated WBI (5 Gy, two doses per week, for 4 weeks). Nine months post the WBI treatment, we applied two-photon microscopy and Doppler optical coherence tomography to measure capillary red-blood-cell (RBC) flux, capillary morphology, and microvascular oxygen partial pressure (PO2) in the cerebral somatosensory cortex in the awake, head-restrained, WPI-treated mice and their age-matched controls, through a cover-glass-sealed chronic cranial window. Thanks to the extended penetration depth with the fluorophore - Alexa680, measurements of capillary blood flow properties (e.g., RBC flux, speed, and linear density) in the cerebral subcortical white matter were enabled. We found that the WBI-treated mice exhibited a significantly decreased capillary RBC flux in the white matter. WBI also caused a significant reduction in capillary diameter, as well as a large (although insignificant) reduction in segment density at the deeper cortical layers (e.g., 600-700 μm), while the other morphological properties (e.g., segment length and tortuosity) were not obviously affected. In addition, we found that PO2 measured in the arterioles and venules, as well as the calculated oxygen saturation and oxygen extraction fraction, were not obviously affected by WBI. Lastly, WBI was associated with a significant increase in the erythrocyte-associated transients of PO2, while the changes of other cerebral capillary PO2 properties (e.g., capillary mean-PO2, RBC-PO2, and InterRBC-PO2) were not significant. Collectively, our findings support the notion that WBI results in persistent cerebral white matter microvascular impairment, which likely contributes to the WBI-induced brain injury and cognitive decline. Further studies are warranted to assess the WBI-induced changes in brain tissue oxygenation and malfunction of the white matter microvasculature as well.
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Affiliation(s)
- Baoqiang Li
- Brain Cognition and Brain Disease Institute, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, Guangdong, China
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, 02129, USA
| | - Andriy Yabluchanskiy
- Vascular Cognitive Impairment and Neurodegeneration Program, Oklahoma Center for Geroscience and Healthy Brain Aging, Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
- Department of Health Promotion Sciences, College of Public Health, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
- The Peggy and Charles Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
| | - Stefano Tarantini
- Vascular Cognitive Impairment and Neurodegeneration Program, Oklahoma Center for Geroscience and Healthy Brain Aging, Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
- Department of Health Promotion Sciences, College of Public Health, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
- The Peggy and Charles Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
- International Training Program in Geroscience, Doctoral School of Basic and Translational Medicine/Department of Public Health, Semmelweis University, Budapest, 1083, Hungary
| | - Srinivasa Rao Allu
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Department of Chemistry, School of Arts and Sciences, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Ikbal Şencan-Eğilmez
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, 02129, USA
- Biophotonics Research Center, Department of Radiology, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Ji Leng
- Brain Cognition and Brain Disease Institute, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, Guangdong, China
| | - Mohammed Ali H Alfadhel
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, 02129, USA
| | - Jason E Porter
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, 02129, USA
| | - Buyin Fu
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, 02129, USA
| | - Chongzhao Ran
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, 02129, USA
| | - Sefik Evren Erdener
- Department of Biomedical Engineering, Boston University, Boston, MA, 02215, USA
| | - David A Boas
- Department of Biomedical Engineering, Boston University, Boston, MA, 02215, USA
| | - Sergei A Vinogradov
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Department of Chemistry, School of Arts and Sciences, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - William E Sonntag
- Vascular Cognitive Impairment and Neurodegeneration Program, Oklahoma Center for Geroscience and Healthy Brain Aging, Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
- The Peggy and Charles Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
| | - Anna Csiszar
- Vascular Cognitive Impairment and Neurodegeneration Program, Oklahoma Center for Geroscience and Healthy Brain Aging, Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
- The Peggy and Charles Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
- International Training Program in Geroscience, Doctoral School of Basic and Translational Medicine/Department of Translational Medicine, Semmelweis University, Budapest, 1083, Hungary
| | - Zoltan Ungvari
- Vascular Cognitive Impairment and Neurodegeneration Program, Oklahoma Center for Geroscience and Healthy Brain Aging, Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA.
- Department of Health Promotion Sciences, College of Public Health, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA.
- The Peggy and Charles Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA.
- International Training Program in Geroscience, Doctoral School of Basic and Translational Medicine/Department of Public Health, Semmelweis University, Budapest, 1083, Hungary.
| | - Sava Sakadžić
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, 02129, USA.
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5
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Nelson MS, Liu Y, Wilson HM, Li B, Rosado-Mendez IM, Rogers JD, Block WF, Eliceiri KW. Multiscale Label-Free Imaging of Fibrillar Collagen in the Tumor Microenvironment. Methods Mol Biol 2023; 2614:187-235. [PMID: 36587127 DOI: 10.1007/978-1-0716-2914-7_13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
With recent advances in cancer therapeutics, there is a great need for improved imaging methods for characterizing cancer onset and progression in a quantitative and actionable way. Collagen, the most abundant extracellular matrix protein in the tumor microenvironment (and the body in general), plays a multifaceted role, both hindering and promoting cancer invasion and progression. Collagen deposition can defend the tumor with immunosuppressive effects, while aligned collagen fiber structures can enable tumor cell migration, aiding invasion and metastasis. Given the complex role of collagen fiber organization and topology, imaging has been a tool of choice to characterize these changes on multiple spatial scales, from the organ and tumor scale to cellular and subcellular level. Macroscale density already aids in the detection and diagnosis of solid cancers, but progress is being made to integrate finer microscale features into the process. Here we review imaging modalities ranging from optical methods of second harmonic generation (SHG), polarized light microscopy (PLM), and optical coherence tomography (OCT) to the medical imaging approaches of ultrasound and magnetic resonance imaging (MRI). These methods have enabled scientists and clinicians to better understand the impact collagen structure has on the tumor environment, at both the bulk scale (density) and microscale (fibrillar structure) levels. We focus on imaging methods with the potential to both examine the collagen structure in as natural a state as possible and still be clinically amenable, with an emphasis on label-free strategies, exploiting intrinsic optical properties of collagen fibers.
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Affiliation(s)
- Michael S Nelson
- Center for Quantitative Cell Imaging, University of Wisconsin-Madison, Madison, WI, USA.,Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, USA
| | - Yuming Liu
- Center for Quantitative Cell Imaging, University of Wisconsin-Madison, Madison, WI, USA
| | - Helen M Wilson
- Center for Quantitative Cell Imaging, University of Wisconsin-Madison, Madison, WI, USA.,Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, USA
| | - Bin Li
- Center for Quantitative Cell Imaging, University of Wisconsin-Madison, Madison, WI, USA.,Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, USA.,Morgridge Institute for Research, Madison, WI, USA
| | - Ivan M Rosado-Mendez
- Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, USA
| | - Jeremy D Rogers
- Morgridge Institute for Research, Madison, WI, USA.,McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, WI, USA
| | - Walter F Block
- Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, USA
| | - Kevin W Eliceiri
- Center for Quantitative Cell Imaging, University of Wisconsin-Madison, Madison, WI, USA. .,Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, USA. .,Morgridge Institute for Research, Madison, WI, USA. .,Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, USA. .,McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, WI, USA.
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6
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Functional photoacoustic microscopy of hemodynamics: a review. Biomed Eng Lett 2022; 12:97-124. [PMID: 35529339 PMCID: PMC9046529 DOI: 10.1007/s13534-022-00220-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 01/24/2022] [Accepted: 01/30/2022] [Indexed: 12/19/2022] Open
Abstract
Functional blood imaging can reflect tissue metabolism and organ viability, which is important for life science and biomedical studies. However, conventional imaging modalities either cannot provide sufficient contrast or cannot support simultaneous multi-functional imaging for hemodynamics. Photoacoustic imaging, as a hybrid imaging modality, can provide sufficient optical contrast and high spatial resolution, making it a powerful tool for in vivo vascular imaging. By using the optical-acoustic confocal alignment, photoacoustic imaging can even provide subcellular insight, referred as optical-resolution photoacoustic microscopy (OR-PAM). Based on a multi-wavelength laser source and developed the calculation methods, OR-PAM can provide multi-functional hemodynamic microscopic imaging of the total hemoglobin concentration (CHb), oxygen saturation (sO2), blood flow (BF), partial oxygen pressure (pO2), oxygen extraction fraction, and metabolic rate of oxygen (MRO2). This concise review aims to systematically introduce the principles and methods to acquire various functional parameters for hemodynamics by photoacoustic microscopy in recent studies, with characteristics and advantages comparison, typical biomedical applications introduction, and future outlook discussion.
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7
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Şencan İ, Esipova T, Kılıç K, Li B, Desjardins M, Yaseen MA, Wang H, Porter JE, Kura S, Fu B, Secomb TW, Boas DA, Vinogradov SA, Devor A, Sakadžić S. Optical measurement of microvascular oxygenation and blood flow responses in awake mouse cortex during functional activation. J Cereb Blood Flow Metab 2022; 42:510-525. [PMID: 32515672 PMCID: PMC8985437 DOI: 10.1177/0271678x20928011] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The cerebral cortex has a number of conserved morphological and functional characteristics across brain regions and species. Among them, the laminar differences in microvascular density and mitochondrial cytochrome c oxidase staining suggest potential laminar variability in the baseline O2 metabolism and/or laminar variability in both O2 demand and hemodynamic response. Here, we investigate the laminar profile of stimulus-induced intravascular partial pressure of O2 (pO2) transients to stimulus-induced neuronal activation in fully awake mice using two-photon phosphorescence lifetime microscopy. Our results demonstrate that stimulus-induced changes in intravascular pO2 are conserved across cortical layers I-IV, suggesting a tightly controlled neurovascular response to provide adequate O2 supply across cortical depth. In addition, we observed a larger change in venular O2 saturation (ΔsO2) compared to arterioles, a gradual increase in venular ΔsO2 response towards the cortical surface, and absence of the intravascular "initial dip" previously reported under anesthesia. This study paves the way for quantification of layer-specific cerebral O2 metabolic responses, facilitating investigation of brain energetics in health and disease and informed interpretation of laminar blood oxygen level dependent functional magnetic resonance imaging signals.
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Affiliation(s)
- İkbal Şencan
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Tatiana Esipova
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.,Department of Chemistry, School of Arts and Sciences, University of Pennsylvania, Philadelphia, PA, USA
| | - Kıvılcım Kılıç
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Baoqiang Li
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Michèle Desjardins
- Department of Physics, Engineering Physics and Optics, Université Laval, QC, Canada
| | - Mohammad A Yaseen
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Hui Wang
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Jason E Porter
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Sreekanth Kura
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Buyin Fu
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Timothy W Secomb
- Department of Physiology, University of Arizona, Tucson, AZ, USA
| | - David A Boas
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Sergei A Vinogradov
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.,Department of Chemistry, School of Arts and Sciences, University of Pennsylvania, Philadelphia, PA, USA
| | - Anna Devor
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA.,Department of Biomedical Engineering, Boston University, Boston, MA, USA.,Department of Neurosciences, University of California San Diego, La Jolla, CA, USA.,Department of Radiology, University of California San Diego, La Jolla, CA, USA
| | - Sava Sakadžić
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
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8
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Stefan S, Kim A, Marchand PJ, Lesage F, Lee J. Deep Learning and Simulation for the Estimation of Red Blood Cell Flux With Optical Coherence Tomography. Front Neurosci 2022; 16:835773. [PMID: 35250467 PMCID: PMC8891630 DOI: 10.3389/fnins.2022.835773] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Accepted: 01/14/2022] [Indexed: 11/13/2022] Open
Abstract
We present a deep learning and simulation-based method to measure cortical capillary red blood cell (RBC) flux using Optical Coherence Tomography (OCT). This method is more accurate than the traditional peak-counting method and avoids any user parametrization, such as a threshold choice. We used data that was simultaneously acquired using OCT and two-photon microscopy to uncover the distribution of parameters governing the height, width, and inter-peak time of peaks in OCT intensity associated with the passage of RBCs. This allowed us to simulate thousands of time-series examples for different flux values and signal-to-noise ratios, which we then used to train a 1D convolutional neural network (CNN). The trained CNN enabled robust measurement of RBC flux across the entire network of hundreds of capillaries.
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Affiliation(s)
- Sabina Stefan
- School of Engineering, Brown University, Providence, RI, United States
| | - Anna Kim
- Department of Neuroscience, Brown University, Providence, RI, United States
| | - Paul J. Marchand
- Department of Electrical Engineering, École Polytechnique de Montréal, Montréal, QC, Canada
| | - Frederic Lesage
- Department of Electrical Engineering, École Polytechnique de Montréal, Montréal, QC, Canada
| | - Jonghwan Lee
- School of Engineering, Brown University, Providence, RI, United States
- Carney Institute for Brain Science, Brown University, Providence, RI, United States
- *Correspondence: Jonghwan Lee,
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9
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Hepburn MS, Foo KY, Wijesinghe P, Munro PRT, Chin L, Kennedy BF. Speckle-dependent accuracy in phase-sensitive optical coherence tomography. OPTICS EXPRESS 2021; 29:16950-16968. [PMID: 34154247 DOI: 10.1364/oe.417954] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 03/26/2021] [Indexed: 05/25/2023]
Abstract
Phase-sensitive optical coherence tomography (OCT) is used to measure motion in a range of techniques, such as Doppler OCT and optical coherence elastography (OCE). In phase-sensitive OCT, motion is typically estimated using a model of the OCT signal derived from a single reflector. However, this approach is not representative of turbid samples, such as tissue, which exhibit speckle. In this study, for the first time, we demonstrate, through theory and experiment that speckle significantly lowers the accuracy of phase-sensitive OCT in a manner not accounted for by the OCT signal-to-noise ratio (SNR). We describe how the inaccuracy in speckle reduces phase difference sensitivity and introduce a new metric, speckle brightness, to quantify the amount of constructive interference at a given location in an OCT image. Experimental measurements show an almost three-fold degradation in sensitivity between regions of high and low speckle brightness at a constant OCT SNR. Finally, we apply these new results in compression OCE to demonstrate a ten-fold improvement in strain sensitivity, and a five-fold improvement in contrast-to-noise by incorporating independent speckle realizations. Our results show that speckle introduces a limit to the accuracy of phase-sensitive OCT and that speckle brightness should be considered to avoid erroneous interpretation of experimental data.
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10
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Silverman RH, Urs R, Tezel G, Yang X, Nelson I, Ketterling JA. Retrobulbar blood flow in rat eyes during acute elevation of intraocular pressure. Exp Eye Res 2021; 207:108606. [PMID: 33930396 DOI: 10.1016/j.exer.2021.108606] [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: 12/29/2020] [Revised: 04/12/2021] [Accepted: 04/22/2021] [Indexed: 10/21/2022]
Abstract
Most studies of the effect of acute elevation of intraocular pressure (IOP) on ocular blood-flow have utilized optical coherence tomography (OCT) to characterize retinal and choroidal flow and vascular density. This study investigates the effect of acute IOP elevation on blood flow velocity in the retrobulbar arteries and veins supplying and draining the eye, which, unlike the retinal and choroidal vasculature, are not directly compressed as IOP is increased. By cannulation of the anterior chamber of 20 Sprague-Dawley rats, we increased IOP in 10 mmHg steps from 10 to 60 mmHg and returned to 10 mmHg. After 1 min at each IOP (and 3 min after return to 10 mmHg), we acquired 18 MHz plane-wave ultrasound data at 3000 compound images/sec for 1.5 s. We produced color-flow Doppler images by digital signal processing of the ultrasound data, identified retrobulbar arteries and veins, generated spectrograms depicting flow velocity over the cardiac cycle and characterized changes of vascular density and perfusion in the orbit overall. Systolic, diastolic and mean velocities and resistive and pulsatile indices were determined from arterial spectrograms at each IOP level. Baseline mean arterial and mean venous velocities averaged 30.9 ± 10.8 and 8.5 ± 3.3 mm/s, respectively. Arterial velocity progressively decreased and resistance indices increased at and above an IOP of 30 mmHg. Mean arterial velocity at 60 mmHg dropped by 55% with respect to baseline, while venous velocity decreased by 20%. Arterial and venous velocities and resistance returned to near baseline after IOP was restored to 10 mmHg. Both vascular density and orbital perfusion decreased with IOP, but while perfusion returned to near normal when IOP returned to 10 mmHg, density remained reduced. Our findings are consistent with OCT-based studies showing reduced perfusion of the retina at levels comparable to retrobulbar arterial flow velocity change with increased IOP. The lesser effect on venous flow is possibly attributable to partial collapse of the venous lumen as volumetric venous outflow decreased at high IOP. The continued reduction in orbital vascular density 3 min after restoration of IOP to 10 mmHg might be attributable to persisting narrowing of capillaries, but this needs to be verified in future studies.
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Affiliation(s)
- Ronald H Silverman
- Department of Ophthalmology, Columbia University Irving Medical Center, New York, NY, USA.
| | - Raksha Urs
- Department of Ophthalmology, Columbia University Irving Medical Center, New York, NY, USA
| | - Gulgun Tezel
- Department of Ophthalmology, Columbia University Irving Medical Center, New York, NY, USA
| | - Xiangjun Yang
- Department of Ophthalmology, Columbia University Irving Medical Center, New York, NY, USA
| | - Inez Nelson
- Department of Ophthalmology, Columbia University Irving Medical Center, New York, NY, USA
| | - Jeffrey A Ketterling
- F.L. Lizzi Center for Biomedical Engineering, Riverside Research, New York, NY, USA
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11
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Xing F, Lee JH, Polucha C, Lee J. Design and optimization of line-field optical coherence tomography at visible wavebands. BIOMEDICAL OPTICS EXPRESS 2021; 12:1351-1365. [PMID: 33796358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 01/25/2021] [Accepted: 01/29/2021] [Indexed: 06/12/2023]
Abstract
Parallel line-field Fourier-domain optical coherence tomography (LF-FDOCT) has emerged to enable relatively higher speeds than the conventional FDOCT system. In the LF-FDOCT, one B-scan is captured at a time instead of scanning the beam to acquire hundreds of A-scans. On the other hand, spectroscopic OCT using the visible waveband provides absorption information over multiple wavelengths at each voxel. This information of spectral absorption enables quantitative measurement of blood oxygenation, voxel by voxel. Here, we presented the design and optimization of a LF-FDOCT system at the visible waveband (520-620 nm), especially using a generic Camera Link area sensor (2048 × 1088 pixels). To optimize the axial resolution and depth of imaging volume, we simulated various parameters and found that two Nyquist optima can exist, the origin and implication of which has been discussed. As a result, our system acquired 1088 A-scans in parallel at the camera's frame rate of 281 frame per second, achieving an equivalent rate of over 300,000 A-scan/s, while minimizing sacrifice in the point spread function (2.8 × 3.1 × 3.2 µm3, x × y × z) and the field of view (750 × 750 × 750 µm3). As an example of application, we presented high-speed imaging of blood oxygenation in the rodent brain cortex.
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Affiliation(s)
- Fangjian Xing
- School of Computer and Electronic information, Nanjing Normal University, Nanjing, 210023, China
- Center for Biomedical Engineering, School of Engineering, Brown University, Providence, Rhode Island 02912, USA
| | - Jang-Hoon Lee
- Center for Biomedical Engineering, School of Engineering, Brown University, Providence, Rhode Island 02912, USA
| | - Collin Polucha
- Center for Biomedical Engineering, School of Engineering, Brown University, Providence, Rhode Island 02912, USA
| | - Jonghwan Lee
- Center for Biomedical Engineering, School of Engineering, Brown University, Providence, Rhode Island 02912, USA
- Carney Institute for Brain Science, Brown University, Providence, Rhode Island 02912, USA
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12
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Xing F, Lee JH, Polucha C, Lee J. Design and optimization of line-field optical coherence tomography at visible wavebands. BIOMEDICAL OPTICS EXPRESS 2021; 12:1351-1365. [PMID: 33796358 PMCID: PMC7984778 DOI: 10.1364/boe.413424] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 01/25/2021] [Accepted: 01/29/2021] [Indexed: 06/17/2023]
Abstract
Parallel line-field Fourier-domain optical coherence tomography (LF-FDOCT) has emerged to enable relatively higher speeds than the conventional FDOCT system. In the LF-FDOCT, one B-scan is captured at a time instead of scanning the beam to acquire hundreds of A-scans. On the other hand, spectroscopic OCT using the visible waveband provides absorption information over multiple wavelengths at each voxel. This information of spectral absorption enables quantitative measurement of blood oxygenation, voxel by voxel. Here, we presented the design and optimization of a LF-FDOCT system at the visible waveband (520-620 nm), especially using a generic Camera Link area sensor (2048 × 1088 pixels). To optimize the axial resolution and depth of imaging volume, we simulated various parameters and found that two Nyquist optima can exist, the origin and implication of which has been discussed. As a result, our system acquired 1088 A-scans in parallel at the camera's frame rate of 281 frame per second, achieving an equivalent rate of over 300,000 A-scan/s, while minimizing sacrifice in the point spread function (2.8 × 3.1 × 3.2 µm3, x × y × z) and the field of view (750 × 750 × 750 µm3). As an example of application, we presented high-speed imaging of blood oxygenation in the rodent brain cortex.
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Affiliation(s)
- Fangjian Xing
- School of Computer and Electronic information, Nanjing Normal University, Nanjing, 210023, China
- Center for Biomedical Engineering, School of Engineering, Brown University, Providence, Rhode Island 02912, USA
| | - Jang-Hoon Lee
- Center for Biomedical Engineering, School of Engineering, Brown University, Providence, Rhode Island 02912, USA
| | - Collin Polucha
- Center for Biomedical Engineering, School of Engineering, Brown University, Providence, Rhode Island 02912, USA
| | - Jonghwan Lee
- Center for Biomedical Engineering, School of Engineering, Brown University, Providence, Rhode Island 02912, USA
- Carney Institute for Brain Science, Brown University, Providence, Rhode Island 02912, USA
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13
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Rakymzhan A, Li Y, Tang P, Wang RK. Differences in cerebral blood vasculature and flow in awake and anesthetized mouse cortex revealed by quantitative optical coherence tomography angiography. J Neurosci Methods 2021; 353:109094. [PMID: 33549637 DOI: 10.1016/j.jneumeth.2021.109094] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 01/27/2021] [Accepted: 01/31/2021] [Indexed: 12/25/2022]
Abstract
BACKGROUND Most of the in vivo neurovascular imaging studies are performed in anesthetized animals. However, anesthesia significantly affects cerebral hemodynamics. NEW METHOD We applied optical coherence tomography (OCT) methods such as optical microangiography (OMAG) and Doppler optical microangiography (DOMAG) to quantitatively evaluate the effect of anesthesia in cerebral vasculature and blood flow in mouse brain. RESULTS The OMAG results indicated the increase of large vessel diameter and capillary density induced by ketamine-xylazine and isoflurane, meaning that both anesthetics caused vasodilation. In addition, the preliminary results from DOMAG showed that isoflurane increased the baseline cerebral blood flow. COMPARISON WITH EXISTING METHODS In comparison with other in vivo imaging modalities, OCT can provide label-free assessment of cortical tissue including tissue morphology, cerebral blood vessel network and flow information down to capillary level, with a large field of view and high imaging speed. CONCLUSIONS OCT angiography methods demonstrated the ability to measure the differences in the baseline morphological and flow parameters of both large and capillary cerebrovascular networks between awake and anesthetized mice.
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Affiliation(s)
- Adiya Rakymzhan
- Department of Bioengineering, University of Washington, 3720 15th Ave NE, Seattle, WA, 98195, USA
| | - Yuandong Li
- Department of Bioengineering, University of Washington, 3720 15th Ave NE, Seattle, WA, 98195, USA
| | - Peijun Tang
- Department of Bioengineering, University of Washington, 3720 15th Ave NE, Seattle, WA, 98195, USA
| | - Ruikang K Wang
- Department of Bioengineering, University of Washington, 3720 15th Ave NE, Seattle, WA, 98195, USA.
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14
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Stefan S, Lee J. Deep learning toolbox for automated enhancement, segmentation, and graphing of cortical optical coherence tomography microangiograms. BIOMEDICAL OPTICS EXPRESS 2020; 11:7325-7342. [PMID: 33409000 PMCID: PMC7747889 DOI: 10.1364/boe.405763] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 11/17/2020] [Accepted: 11/17/2020] [Indexed: 05/03/2023]
Abstract
Optical coherence tomography angiography (OCTA) is becoming increasingly popular for neuroscientific study, but it remains challenging to objectively quantify angioarchitectural properties from 3D OCTA images. This is mainly due to projection artifacts or "tails" underneath vessels caused by multiple-scattering, as well as the relatively low signal-to-noise ratio compared to fluorescence-based imaging modalities. Here, we propose a set of deep learning approaches based on convolutional neural networks (CNNs) to automated enhancement, segmentation and gap-correction of OCTA images, especially of those obtained from the rodent cortex. Additionally, we present a strategy for skeletonizing the segmented OCTA and extracting the underlying vascular graph, which enables the quantitative assessment of various angioarchitectural properties, including individual vessel lengths and tortuosity. These tools, including the trained CNNs, are made publicly available as a user-friendly toolbox for researchers to input their OCTA images and subsequently receive the underlying vascular network graph with the associated angioarchitectural properties.
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Affiliation(s)
- Sabina Stefan
- Center for Biomedical Engineering, School of Engineering, Brown University, Providence, RI 02912, USA
| | - Jonghwan Lee
- Center for Biomedical Engineering, School of Engineering, Brown University, Providence, RI 02912, USA
- Carney Institute for Brain Science, Brown University, Providence, RI 02912, USA
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15
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Intact in vivo visualization of telencephalic microvasculature in medaka using optical coherence tomography. Sci Rep 2020; 10:19831. [PMID: 33199719 PMCID: PMC7669881 DOI: 10.1038/s41598-020-76468-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Accepted: 10/28/2020] [Indexed: 11/09/2022] Open
Abstract
To date, various human disease models in small fish-such as medaka (Oryzias lapties)-have been developed for medical and pharmacological studies. Although genetic and environmental homogeneities exist, disease progressions can show large individual differences in animal models. In this study, we established an intact in vivo angiographic approach and explored vascular networks in the telencephalon of wild-type adult medaka using the spectral-domain optical coherence tomography. Our approach, which required neither surgical operations nor labeling agents, allowed to visualize blood vessels in medaka telencephala as small as about 8 µm, that is, almost the size of the blood cells of medaka. Besides, we could show the three-dimensional microvascular distribution in the medaka telencephalon. Therefore, the intact in vivo imaging via optical coherence tomography can be used to perform follow-up studies on cerebrovascular alterations in metabolic syndrome and their associations with neurodegenerative disease models in medaka.
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16
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Bordoni L, Li B, Kura S, Boas DA, Sakadžić S, Østergaard L, Frische S, Gutiérrez-Jiménez E. Quantification of Capillary Perfusion in an Animal Model of Acute Intracranial Hypertension. J Neurotrauma 2020; 38:446-454. [PMID: 32998634 DOI: 10.1089/neu.2019.6901] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Intracranial hypertension (IH) is a common feature of many pathologies, including brain edema. In the brain, the extended network of capillaries ensures blood flow to meet local metabolic demands. Capillary circulation may be severely affected by IH, but no studies have quantified the effect of intracranial pressure (ICP) and cerebral perfusion pressure (CPP) on capillary perfusion during the development of brain edema. We used optical coherence tomography angiography to quantify relative changes of fractional perfused volume (FPV) in cortical capillaries and simultaneously monitored ICP and blood pressure (BP) in anesthetized male C57Bl/6NTac mice during development of brain edema induced by water intoxication (WI) within 30 min. WI induced severe IH and brain herniation. ICP and CPP reached 90.2 mm Hg and 38.4 mm Hg, respectively. FPV was significantly affected already at normal ICP (ICP <15 mm Hg, slope ≈ -1.46, p < 0.001) and, at the onset of IH (ICP = 20-22 mm Hg), FPV was 17.9 ± 13.3% lower than baseline. A decreasing trend was observed until the ICP peak (Δ%FPV = -43.6 ± 19.2%). In the ICP range of 7-42 mm Hg, relative changes in FPV were significantly correlated with ICP, BP, and CPP (p < 0.001), with ICP and CPP being the best predictors. In conclusion, elevated ICP induces a gradual collapse of the cerebral microvasculature, which is initiated before the clinical threshold of IH. In summary, the estimate of capillary perfusion might be essential in patients with IH to assess the state of the brain microcirculation and to improve the availability of oxygen and nutrients to the brain.
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Affiliation(s)
- Luca Bordoni
- Institute of Biomedicine, Aarhus University, Aarhus C, Denmark
| | - Baoqiang Li
- Brain Cognition and Brain Disease Institute, Chinese Academy of Sciences, Shenzhen, China.,Shenzhen-Hong Kong Institute of Brain Science, Shenzhen Fundamental Research Institutions, Shenzhen, China
| | - Sreekanth Kura
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts, USA
| | - David A Boas
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts, USA.,Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts, USA
| | - Sava Sakadžić
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts, USA
| | - Leif Østergaard
- Department of Clinical Medicine, Aarhus University, Aarhus C, Denmark.,Department of Neuroradiology, Aarhus University Hospital, Aarhus C, Denmark
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17
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Beykin G, Norcia AM, Srinivasan VJ, Dubra A, Goldberg JL. Discovery and clinical translation of novel glaucoma biomarkers. Prog Retin Eye Res 2020; 80:100875. [PMID: 32659431 DOI: 10.1016/j.preteyeres.2020.100875] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2020] [Revised: 06/01/2020] [Accepted: 06/04/2020] [Indexed: 12/16/2022]
Abstract
Glaucoma and other optic neuropathies are characterized by progressive dysfunction and loss of retinal ganglion cells and their axons. Given the high prevalence of glaucoma-related blindness and the availability of treatment options, improving the diagnosis and precise monitoring of progression in these conditions is paramount. Here we review recent progress in the development of novel biomarkers for glaucoma in the context of disease pathophysiology and we propose future steps for the field, including integration of exploratory biomarker outcomes into prospective therapeutic trials. We anticipate that, when validated, some of the novel glaucoma biomarkers discussed here will prove useful for clinical diagnosis and prediction of progression, as well as monitoring of clinical responses to standard and investigational therapies.
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Affiliation(s)
- Gala Beykin
- Spencer Center for Vision Research at Stanford University, 2370 Watson Ct, Palo Alto, CA, 94303, USA.
| | - Anthony M Norcia
- Department of Psychology, Stanford University, 290 Jane Stanford Way, Stanford, CA, 94305, USA.
| | - Vivek J Srinivasan
- Department of Biomedical Engineering, University of California, Davis, One Shields Ave, Davis, CA, 95616, USA; Department of Ophthalmology and Vision Science, University of California Davis School of Medicine, 4610 X St, Sacramento, CA, 96817, USA.
| | - Alfredo Dubra
- Spencer Center for Vision Research at Stanford University, 2370 Watson Ct, Palo Alto, CA, 94303, USA.
| | - Jeffrey L Goldberg
- Spencer Center for Vision Research at Stanford University, 2370 Watson Ct, Palo Alto, CA, 94303, USA.
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18
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Wu C, Qiao Z, Zhang N, Li X, Fan J, Song H, Ai D, Yang J, Huang Y. Phase unwrapping based on a residual en-decoder network for phase images in Fourier domain Doppler optical coherence tomography. BIOMEDICAL OPTICS EXPRESS 2020; 11:1760-1771. [PMID: 32341846 PMCID: PMC7173896 DOI: 10.1364/boe.386101] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 02/19/2020] [Accepted: 02/27/2020] [Indexed: 06/01/2023]
Abstract
To solve the phase unwrapping problem for phase images in Fourier domain Doppler optical coherence tomography (DOCT), we propose a deep learning-based residual en-decoder network (REDN) method. In our approach, we reformulate the definition for obtaining the true phase as obtaining an integer multiple of 2π at each pixel by semantic segmentation. The proposed REDN architecture can provide recognition performance with pixel-level accuracy. To address the lack of phase images that are noise and wrapping free from DOCT systems for training, we used simulated images synthesized with DOCT phase image background noise features. An evaluation study on simulated images, DOCT phase images of phantom milk flowing in a plastic tube and a mouse artery, was performed. Meanwhile, a comparison study with recently proposed deep learning-based DeepLabV3+ and PhaseNet methods for signal phase unwrapping and traditional modified networking programming (MNP) method was also performed. Both visual inspection and quantitative metrical evaluation based on accuracy, specificity, sensitivity, root-mean-square-error, total-variation, and processing time demonstrate the robustness, effectiveness and superiority of our method. The proposed REDN method will benefit accurate and fast DOCT phase image-based diagnosis and evaluation when the detected phase is wrapped and will enrich the deep learning-based image processing platform for DOCT images.
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Affiliation(s)
- Chuanchao Wu
- School of Optics and Photonics, Beijing Institute of Technology, No. 5 South Zhongguancun Street, Haidian, Beijing 100081, China
| | - Zhengyu Qiao
- School of Optics and Photonics, Beijing Institute of Technology, No. 5 South Zhongguancun Street, Haidian, Beijing 100081, China
| | - Nan Zhang
- School of Optics and Photonics, Beijing Institute of Technology, No. 5 South Zhongguancun Street, Haidian, Beijing 100081, China
| | - Xiaochen Li
- School of Optics and Photonics, Beijing Institute of Technology, No. 5 South Zhongguancun Street, Haidian, Beijing 100081, China
| | - Jingfan Fan
- School of Optics and Photonics, Beijing Institute of Technology, No. 5 South Zhongguancun Street, Haidian, Beijing 100081, China
| | - Hong Song
- School of Computer Science and Technology, Beijing Institute of Technology, No. 5 South Zhongguancun Street, Haidian, Beijing 100081, China
| | - Danni Ai
- School of Optics and Photonics, Beijing Institute of Technology, No. 5 South Zhongguancun Street, Haidian, Beijing 100081, China
| | - Jian Yang
- School of Optics and Photonics, Beijing Institute of Technology, No. 5 South Zhongguancun Street, Haidian, Beijing 100081, China
| | - Yong Huang
- School of Optics and Photonics, Beijing Institute of Technology, No. 5 South Zhongguancun Street, Haidian, Beijing 100081, China
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19
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Pijewska E, Sylwestrzak M, Gorczynska I, Tamborski S, Pawlak MA, Szkulmowski M. Blood flow rate estimation in optic disc capillaries and vessels using Doppler optical coherence tomography with 3D fast phase unwrapping. BIOMEDICAL OPTICS EXPRESS 2020; 11:1336-1353. [PMID: 32206414 PMCID: PMC7075620 DOI: 10.1364/boe.382155] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 01/13/2020] [Accepted: 01/24/2020] [Indexed: 05/25/2023]
Abstract
The retinal volumetric flow rate contains useful information not only for ophthalmology but also for the diagnosis of common civilization diseases such as diabetes, Alzheimer's disease, or cerebrovascular diseases. Non-invasive optical methods for quantitative flow assessment, such as Doppler optical coherence tomography (OCT), have certain limitations. One is the phase wrapping that makes simultaneous calculations of the flow in all human retinal vessels impossible due to a very large span of flow velocities. We demonstrate that three-dimensional Doppler OCT combined with three-dimensional four Fourier transform fast phase unwrapping (3D 4FT FPU) allows for the calculation of the volumetric blood flow rate in real-time by the implementation of the algorithms in a graphics processing unit (GPU). The additive character of the flow at the furcations is proven using a microfluidic device with controlled flow rates as well as in the retinal veins bifurcations imaged in the optic disc area of five healthy volunteers. We show values of blood flow rates calculated for retinal capillaries and vessels with diameters in the range of 12-150 µm. The potential of quantitative measurement of retinal blood flow volume includes noninvasive detection of carotid artery stenosis or occlusion, measuring vascular reactivity and evaluation of vessel wall stiffness.
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Affiliation(s)
- Ewelina Pijewska
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Torun, Grudziądzka 5, 87-100 Torun, Poland
| | - Marcin Sylwestrzak
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Torun, Grudziądzka 5, 87-100 Torun, Poland
| | - Iwona Gorczynska
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Torun, Grudziądzka 5, 87-100 Torun, Poland
| | - Szymon Tamborski
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Torun, Grudziądzka 5, 87-100 Torun, Poland
| | - Mikolaj A. Pawlak
- Department of Neurology and Cerebrovascular Disorders, Poznan University of Medical Sciences, Fredry 10, 61-701 Poznań, Poland
- Department of Clinical Genetics, Erasmus MC, PO Box 2040, 3000 CA Rotterdam, The Netherlands
| | - Maciej Szkulmowski
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Torun, Grudziądzka 5, 87-100 Torun, Poland
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20
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Almog IF, Chen F, Senova S, Fomenko A, Gondard E, Sacher WD, Lozano AM, Poon JKS. Full-field swept-source optical coherence tomography and neural tissue classification for deep brain imaging. JOURNAL OF BIOPHOTONICS 2020; 13:e201960083. [PMID: 31710771 PMCID: PMC7065632 DOI: 10.1002/jbio.201960083] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2019] [Revised: 10/19/2019] [Accepted: 11/06/2019] [Indexed: 05/28/2023]
Abstract
Optical coherence tomography can differentiate brain regions with intrinsic contrast and at a micron scale resolution. Such a device can be particularly useful as a real-time neurosurgical guidance tool. We present, to our knowledge, the first full-field swept-source optical coherence tomography system operating near a wavelength of 1310 nm. The proof-of-concept system was integrated with an endoscopic probe tip, which is compatible with deep brain stimulation keyhole neurosurgery. Neuroimaging experiments were performed on ex vivo brain tissues and in vivo in rat brains. Using classification algorithms involving texture features and optical attenuation, images were successfully classified into three brain tissue types.
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Affiliation(s)
- Ilan Felts Almog
- Edward S. Rogers Sr. Department of Electrical and Computer EngineeringUniversity of TorontoTorontoOntarioCanada
- Krembil Research InstituteToronto Western HospitalTorontoOntarioCanada
| | - Fu‐Der Chen
- Edward S. Rogers Sr. Department of Electrical and Computer EngineeringUniversity of TorontoTorontoOntarioCanada
- Krembil Research InstituteToronto Western HospitalTorontoOntarioCanada
| | - Suhan Senova
- Krembil Research InstituteToronto Western HospitalTorontoOntarioCanada
- Department of NeurosurgeryCentre Hospitalier Universitaire Henri‐Mondor, APHPCréteilFrance
- INSERM Unit 955, Institut Mondor de Recherche Biomédicale, Université Paris‐EstCréteilFrance
| | - Anton Fomenko
- Krembil Research InstituteToronto Western HospitalTorontoOntarioCanada
| | - Elise Gondard
- Krembil Research InstituteToronto Western HospitalTorontoOntarioCanada
| | - Wesley D. Sacher
- Edward S. Rogers Sr. Department of Electrical and Computer EngineeringUniversity of TorontoTorontoOntarioCanada
- Max Planck Institute of Microstructure PhysicsHalleGermany
| | - Andres M. Lozano
- Krembil Research InstituteToronto Western HospitalTorontoOntarioCanada
- Division of Neurosurgery, Department of SurgeryToronto Western HospitalTorontoOntarioCanada
| | - Joyce K. S. Poon
- Edward S. Rogers Sr. Department of Electrical and Computer EngineeringUniversity of TorontoTorontoOntarioCanada
- Krembil Research InstituteToronto Western HospitalTorontoOntarioCanada
- Max Planck Institute of Microstructure PhysicsHalleGermany
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21
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Dolezyczek H, Tamborski S, Majka P, Sampson D, Wojtkowski M, Wilczyński G, Szkulmowski M, Malinowska M. In vivo brain imaging with multimodal optical coherence microscopy in a mouse model of thromboembolic photochemical stroke. NEUROPHOTONICS 2020; 7:015002. [PMID: 32016131 PMCID: PMC6977401 DOI: 10.1117/1.nph.7.1.015002] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 12/19/2019] [Indexed: 06/10/2023]
Abstract
We used a new multimodal imaging system that combines optical coherence microscopy and brightfield microscopy. Using this in vivo brain monitoring approach and cranial window implantation, we three-dimensionally visualized the vascular network during thrombosis, with high temporal (18 s) and spatial (axial, 2.5 μ m ; lateral, 2.2 μ m ) resolution. We used a modified mouse model of photochemical thromboembolic stroke in order to more accurately parallel human stroke. Specifically, we applied green laser illumination to focally occlude a branch of the middle cerebral artery. Despite the recanalization of the superficial arteries at 24 h after stroke, no blood flow was detected in the small vessels within deeper regions. Moreover, after 24 h of stroke progression, scattering signal enhancement was observed within the stroke region. We also evaluated the infarct extent and shape histologically. In summary, we present a novel approach for real-time mouse brain monitoring and ischemic variability analysis. This multimodal imaging method permits the analysis of thrombosis progression and reperfusion. Additionally and importantly, the system could be used to study the effect of poststroke drug treatments on blood flow in small arteries and capillaries of the brain.
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Affiliation(s)
- Hubert Dolezyczek
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
| | - Szymon Tamborski
- Nicolaus Copernicus University, Institute of Physics, Faculty of Physics, Astronomy and Informatics, Torun, Poland
| | - Piotr Majka
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
| | - Danuta Sampson
- University of Surrey, Surrey Biophotonics, Centre for Vision, Speech and Signal Processing, School of Biosciences and Medicine, Guildford, United Kingdom
| | - Maciej Wojtkowski
- Institute of Physical Chemistry of the Polish Academy of Sciences, Warsaw, Poland
| | - Grzegorz Wilczyński
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
| | - Maciej Szkulmowski
- Nicolaus Copernicus University, Institute of Physics, Faculty of Physics, Astronomy and Informatics, Torun, Poland
| | - Monika Malinowska
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
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22
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Tsai MT, Wang YL, Yeh TW, Lee HC, Chen WJ, Ke JL, Lee YJ. Early detection of enamel demineralization by optical coherence tomography. Sci Rep 2019; 9:17154. [PMID: 31748675 PMCID: PMC6868170 DOI: 10.1038/s41598-019-53567-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 10/18/2019] [Indexed: 01/03/2023] Open
Abstract
Enamel is the outermost layer of the tooth that protects it from invasion. In general, an acidic environment accelerates tooth demineralization, leading to the formation of cavities. Scanning electron microscopy (SEM) is conventionally used as an in vitro tool for the observation of tooth morphology changes with acid attacks. Yet, SEM has intrinsic limitations for the potential application of in vivo detection in the early demineralization process. In this study, a high-resolution optical coherence tomography (OCT) system with the axial and transverse resolutions of 2.0 and 2.7 μm in teeth has been utilized for characterizing the effect of the acidic environment (simulated by phosphoric acid) on the enamel topology. The scattering coefficient and the surface roughness of enamel can be directly derived from the OCT results, enabling a quantitative evaluation of the topology changes with demineralization. The dynamic process induced by the acid application is also recorded and analyzed with OCT, depicting the evolution of the demineralization process on enamel. Notably, the estimated enamel scattering coefficient and surface roughness significantly increase with the application time of acid and the results illustrate that the values of both parameters after demineralization are significantly larger than those obtained before the demineralization, illustrating both parameters could be effective to differentiate the healthy and demineralized teeth and determine the severity. The obtained results unambiguously illustrate that demineralization of the tooth surface can be successfully detected by OCT and further used as an indicator of early-stage cavity formation.
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Affiliation(s)
- Meng-Tsan Tsai
- Department of Electrical Engineering, Chang Gung University, Taoyuan, 33302, Taiwan.,Department of Neurosurgery, Chang Gung Memorial Hospital, Linkou, 33305, Taiwan
| | - Yen-Li Wang
- Department of Periodontics, Chang Gung Memorial Hospital, Taoyuan, 33378, Taiwan. .,College of Medicine, Chang Gung University, Taoyuan, 33302, Taiwan.
| | - Ting-Wei Yeh
- Institute of Electro-Optical Science and Technology, National Taiwan Normal University, Taipei, 11677, Taiwan
| | - Hsiang-Chieh Lee
- Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei, 10617, Taiwan.,Department of Electrical Engineering, National Taiwan University, Taipei, 10617, Taiwan
| | - Wen-Ju Chen
- Department of Electrical Engineering, Chang Gung University, Taoyuan, 33302, Taiwan.,Department of Periodontics, Chang Gung Memorial Hospital, Taoyuan, 33378, Taiwan
| | - Jia-Ling Ke
- Institute of Electro-Optical Science and Technology, National Taiwan Normal University, Taipei, 11677, Taiwan
| | - Ya-Ju Lee
- Institute of Electro-Optical Science and Technology, National Taiwan Normal University, Taipei, 11677, Taiwan.
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23
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Erdener ŞE, Dalkara T. Small Vessels Are a Big Problem in Neurodegeneration and Neuroprotection. Front Neurol 2019; 10:889. [PMID: 31474933 PMCID: PMC6707104 DOI: 10.3389/fneur.2019.00889] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2019] [Accepted: 08/01/2019] [Indexed: 12/11/2022] Open
Abstract
The cerebral microcirculation holds a critical position to match the high metabolic demand by neuronal activity. Functionally, microcirculation is virtually inseparable from other nervous system cells under both physiological and pathological conditions. For successful bench-to-bedside translation of neuroprotection research, the role of microcirculation in acute and chronic neurodegenerative disorders appears to be under-recognized, which may have contributed to clinical trial failures with some neuroprotectants. Increasing data over the last decade suggest that microcirculatory impairments such as endothelial or pericyte dysfunction, morphological irregularities in capillaries or frequent dynamic stalls in blood cell flux resulting in excessive heterogeneity in capillary transit may significantly compromise tissue oxygen availability. We now know that ischemia-induced persistent abnormalities in capillary flow negatively impact restoration of reperfusion after recanalization of occluded cerebral arteries. Similarly, microcirculatory impairments can accompany or even precede neural loss in animal models of several neurodegenerative disorders including Alzheimer's disease. Macrovessels are relatively easy to evaluate with radiological or experimental imaging methods but they cannot faithfully reflect the downstream microcirculatory disturbances, which may be quite heterogeneous across the tissue at microscopic scale and/or happen fast and transiently. The complexity and size of the elements of microcirculation, therefore, require utilization of cutting-edge imaging techniques with high spatiotemporal resolution as well as multidisciplinary team effort to disclose microvascular-neurodegenerative connection and to test treatment approaches to advance the field. Developments in two photon microscopy, ultrafast ultrasound, and optical coherence tomography provide valuable experimental tools to reveal those microscopic events with high resolution. Here, we review the up-to-date advances in understanding of the primary microcirculatory abnormalities that can result in neurodegenerative processes and the combined neurovascular protection approaches that can prevent acute as well as chronic neurodegeneration.
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Affiliation(s)
- Şefik Evren Erdener
- Institute of Neurological Sciences and Psychiatry, Hacettepe University, Ankara, Turkey
| | - Turgay Dalkara
- Institute of Neurological Sciences and Psychiatry, Hacettepe University, Ankara, Turkey.,Department of Neurology, Faculty of Medicine, Hacettepe University, Ankara, Turkey
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24
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Merkle CW, Zhu J, Bernucci MT, Srinivasan VJ. Dynamic Contrast Optical Coherence Tomography reveals laminar microvascular hemodynamics in the mouse neocortex in vivo. Neuroimage 2019; 202:116067. [PMID: 31394180 DOI: 10.1016/j.neuroimage.2019.116067] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 07/01/2019] [Accepted: 08/01/2019] [Indexed: 12/18/2022] Open
Abstract
Studies of flow-metabolism coupling often presume that microvessel architecture is a surrogate for blood flow. To test this assumption, we introduce an in vivo Dynamic Contrast Optical Coherence Tomography (DyC-OCT) method to quantify layer-resolved microvascular blood flow and volume across the full depth of the mouse neocortex, where the angioarchitecture has been previously described. First, we cross-validate average DyC-OCT cortical flow against conventional Doppler OCT flow. Next, with laminar DyC-OCT, we discover that layer 4 consistently exhibits the highest microvascular blood flow, approximately two-fold higher than the outer cortical layers. While flow differences between layers are well-explained by microvascular volume and density, flow differences between subjects are better explained by transit time. Finally, from layer-resolved tracer enhancement, we also infer that microvascular hematocrit increases in deep cortical layers, consistent with predictions of plasma skimming. Altogether, our results show that while the cortical blood supply derives mainly from the pial surface, laminar hemodynamics ensure that the energetic needs of individual cortical layers are met. The laminar trends reported here provide data that links predictions based on the cortical angioarchitecture to cerebrovascular physiology in vivo.
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Affiliation(s)
- Conrad W Merkle
- Department of Biomedical Engineering, University of California Davis, Davis, CA, 95616, USA
| | - Jun Zhu
- Department of Biomedical Engineering, University of California Davis, Davis, CA, 95616, USA
| | - Marcel T Bernucci
- Department of Biomedical Engineering, University of California Davis, Davis, CA, 95616, USA
| | - Vivek J Srinivasan
- Department of Biomedical Engineering, University of California Davis, Davis, CA, 95616, USA; Department of Ophthalmology and Vision Science, University of California Davis School of Medicine, Sacramento, CA, 95817, USA.
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25
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Wei W, Li Y, Xie Z, Deegan AJ, Wang RK. Spatial and Temporal Heterogeneities of Capillary Hemodynamics and Its Functional Coupling During Neural Activation. IEEE TRANSACTIONS ON MEDICAL IMAGING 2019; 38:1295-1303. [PMID: 30489265 PMCID: PMC6563900 DOI: 10.1109/tmi.2018.2883244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The cerebral vascular system provides a means to meet the constant metabolic needs of neuronal activities in the brain. Within the cerebral capillary bed, the interactions of spatial and temporal hemodynamics play a deterministic role in oxygen diffusion, however, the progression of which remains unclear. Taking the advantages of high-spatiotemporal resolution of optical coherence tomography capillary velocimetry designed with the eigen-decomposition statistical analysis, we investigated intrinsic red blood cell (RBC) velocities and their spatiotemporal adjustment within the capillaries permeating mouse cerebral cortex during electrical stimulation of contralateral hind paw. We found that the mean capillary transit velocity (mCTV) is increased and its temporal fluctuation bandwidth (TFB) is broadened within hind-paw somatosensory cortex. In addition, the degree to which the mCTV is increased negatively correlates with resting state mCTV, and the degree to which the TFB is increased negatively correlates with both the resting state mCTV and the TFB. In order to confirm the changes are due to hemodynamic regulation, we performed angiographic analyses and found that the vessel density remains almost constant, suggesting the observed functional activation does not involve recruitment of reserved capillaries. To further differentiate the contributions of the mCTV and the TFB to the spatiotemporally coupled hemodynamics, changes in the mCTV and TBF of the capillary flow were modeled and investigated through a Monte Carlo simulation. The results suggest that neural activation evokes the spatial transit time homogenization within the capillary bed, which is regulated via both the heterogeneous acceleration of RBC flow and the heterogeneous increase of temporal RBC fluctuation, ensuring sufficient oxygenation during functional hyperemia.
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26
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Tang J, Erdener SE, Sunil S, Boas DA. Normalized field autocorrelation function-based optical coherence tomography three-dimensional angiography. JOURNAL OF BIOMEDICAL OPTICS 2019; 24:1-8. [PMID: 30868803 PMCID: PMC6414735 DOI: 10.1117/1.jbo.24.3.036005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Accepted: 02/06/2019] [Indexed: 05/02/2023]
Abstract
Optical coherence tomography angiography (OCTA) has been widely used for en face visualization of the microvasculature, but is challenged for real three-dimensional (3-D) topologic imaging due to the "tail" artifacts that appear below large vessels. Further, OCTA is generally incapable of differentiating descending arterioles from ascending venules. We introduce a normalized field autocorrelation function-based OCTA (g1-OCTA), which minimizes the tail artifacts and is capable of distinguishing penetrating arterioles from venules in the 3-D image. g1 ( τ ) is calculated from repeated optical coherence tomography (OCT) acquisitions for each spatial location. The decay amplitude of g1 ( τ ) is retrieved to represent the dynamics for each voxel. To account for the small g1 ( τ ) decay in capillaries where red blood cells are flowing slowly and discontinuously, Intralipid is injected to enhance the OCT signal. We demonstrate that the proposed technique realizes 3-D OCTA with negligible tail projections and the penetrating arteries are readily identified. In addition, compared to regular OCTA, the proposed g1-OCTA largely increased the depth-of-field. This technique provides a more accurate rendering of the vascular 3-D anatomy and has the potential for more quantitative characterization of vascular networks.
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Affiliation(s)
- Jianbo Tang
- Boston University, Neurophotonics Center, Department of Biomedical Engineering, Boston, Massachusetts, United States
- Harvard Medical School, Massachusetts General Hospital, Boston, Massachusetts, United States
- Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, Massachusetts, United States
- Address all correspondence to Jianbo Tang, E-mail:
| | - Sefik Evren Erdener
- Boston University, Neurophotonics Center, Department of Biomedical Engineering, Boston, Massachusetts, United States
- Harvard Medical School, Massachusetts General Hospital, Boston, Massachusetts, United States
- Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, Massachusetts, United States
| | - Smrithi Sunil
- Boston University, Neurophotonics Center, Department of Biomedical Engineering, Boston, Massachusetts, United States
| | - David A. Boas
- Boston University, Neurophotonics Center, Department of Biomedical Engineering, Boston, Massachusetts, United States
- Harvard Medical School, Massachusetts General Hospital, Boston, Massachusetts, United States
- Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, Massachusetts, United States
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27
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Pijewska E, Gorczynska I, Szkulmowski M. Computationally effective 2D and 3D fast phase unwrapping algorithms and their applications to Doppler optical coherence tomography. BIOMEDICAL OPTICS EXPRESS 2019; 10:1365-1382. [PMID: 30891352 PMCID: PMC6420292 DOI: 10.1364/boe.10.001365] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 01/20/2019] [Accepted: 01/22/2019] [Indexed: 05/07/2023]
Abstract
We propose a simplification for a robust and easy to implement fast phase unwrapping (FPU) algorithm that is used to solve the phase wrapping problem encountered in various fields of optical imaging and metrology. We show that the number of necessary computations using the algorithm can be reduced compared to its original version. FPU can be easily extended from two to three spatial dimensions. We demonstrate the applicability of the two- and three-dimensional FPU algorithm for Doppler optical coherence tomography (DOCT) in numerical simulations, and in the imaging of a flow phantom and blood flow in the human retina in vivo. We introduce an FPU applicability plot for use as a guide in the selection of the most suitable version of the algorithm depending on the phase noise in the acquired data. This plot uses the circular standard deviation of the wrapped phase distribution as a measure of noise and relates it to the root-mean-square error of the recovered, unwrapped phase.
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28
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Ma Z, Luo S, Yu M, Liu J, Zhao Y, Yu Y, Lv J, Zhang X, Wang Y. Assessment of microvasculature flow state with a high speed all-optic dual-modal system of optical coherence tomography and photoacoustic imaging. BIOMEDICAL OPTICS EXPRESS 2018; 9:6103-6115. [PMID: 31065416 PMCID: PMC6490985 DOI: 10.1364/boe.9.006103] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Revised: 10/12/2018] [Accepted: 11/04/2018] [Indexed: 05/13/2023]
Abstract
We propose a high speed all-optic dual-modal system that combines spectral domain optical coherence tomography (SDOCT) and photoacoustic imaging (PAI) to evaluate microvasculature flow states. A homodyne interferometer was used to remotely detect the surface vibration caused by photoacoustic (PA) waves. The PA excitation, PA probing and SDOCT probing beams share the same X-Y galvanometer scanner to perform fast two-dimensional scanning. In addition, we introduced multi-excitation, dual-channel acquisition and sensitivity compensation to improve the imaging speed of the PAI sub-system. The total time for imaging a sample with 256 × 256 pixels is less than 1 minute. The performance of the proposed system was verified by in vivo imaging of the vascular system in a mouse pinna with normal and then blocked blood circulations. The experimental results indicate that the proposed system is capable of revealing different blood flow states (static and moving) and is useful for the study of diseases related to functional blood supply.
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Affiliation(s)
- Zhenhe Ma
- School of Control Engineering, Northeastern University at Qinhuangdao, Qinhuangdao 066004, China
| | - Shuzhuo Luo
- School of Computer Science and Engineering, Northeastern University, Shenyang 110004, China
| | - Menghan Yu
- School of Control Engineering, Northeastern University at Qinhuangdao, Qinhuangdao 066004, China
| | - Jian Liu
- School of Control Engineering, Northeastern University at Qinhuangdao, Qinhuangdao 066004, China
| | - Yuqian Zhao
- School of Control Engineering, Northeastern University at Qinhuangdao, Qinhuangdao 066004, China
| | - Yao Yu
- School of Control Engineering, Northeastern University at Qinhuangdao, Qinhuangdao 066004, China
| | - Jiangtao Lv
- School of Control Engineering, Northeastern University at Qinhuangdao, Qinhuangdao 066004, China
| | - Xiaofang Zhang
- School of Optoelectronics, Beijing Institute of Technology, Beijing 100081, China
| | - Yi Wang
- School of Control Engineering, Northeastern University at Qinhuangdao, Qinhuangdao 066004, China
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29
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Akif A, Walek K, Polucha C, Lee J. Doppler OCT clutter rejection using variance minimization and offset extrapolation. BIOMEDICAL OPTICS EXPRESS 2018; 9:5340-5352. [PMID: 30460132 PMCID: PMC6238902 DOI: 10.1364/boe.9.005340] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Revised: 10/05/2018] [Accepted: 10/05/2018] [Indexed: 05/02/2023]
Abstract
Doppler optical coherence tomography (OCT) is widely used for high-resolution mapping of flow velocities and is based on analysis of temporal changes in the phase of an OCT signal (i.e., how fast the OCT signal rotates in the complex plane). Determination of the rate of phase change or rotation speed critically depends on the center of rotation. Here, we demonstrate the bias in high-pass filtering, the current widely used method to determine the center of rotation, and propose two advanced methods for Doppler OCT clutter rejection. The bias in the high-pass filtering method becomes increasingly significant with lower velocities or larger signal noise. Two novel methods based on variance minimization and offset extrapolation can potentially reduce this bias and thereby improve the accuracy of Doppler OCT measurements of flow velocities, even for low-velocity and/or high-noise signals. The two novel methods and the current standard method (high-pass filtering) have been tested in combination with several currently used velocity measurement algorithms: Kasai, autocorrelation function fitting, and maximum likelihood estimation. The newly proposed methods are shown to improve the accuracy in both the center of rotation and resultant velocity by up to 60 percentage points and reduce the flow conservation error by 30% when applied to in vivo cerebral blood flow imaging of the rodent brain cortex.
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Affiliation(s)
- Adil Akif
- Center for Biomedical Engineering, School of Engineering, Brown University, Providence, RI 02906, USA
| | - Konrad Walek
- Department of Neuroscience, Brown University, Providence, RI 02906, USA
- Warren A. Alpert Medical School, Brown University, Providence, RI 02906, USA
| | - Collin Polucha
- Center for Biomedical Engineering, School of Engineering, Brown University, Providence, RI 02906, USA
| | - Jonghwan Lee
- Center for Biomedical Engineering, School of Engineering, Brown University, Providence, RI 02906, USA
- Carney Institute for Brain Science, Brown University, Providence, RI 02906, USA
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30
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Jones JS, Small DM, Nishimura N. In Vivo Calcium Imaging of Cardiomyocytes in the Beating Mouse Heart With Multiphoton Microscopy. Front Physiol 2018; 9:969. [PMID: 30108510 PMCID: PMC6079295 DOI: 10.3389/fphys.2018.00969] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2018] [Accepted: 07/02/2018] [Indexed: 12/22/2022] Open
Abstract
Background: Understanding the microscopic dynamics of the beating heart has been challenging due to the technical nature of imaging with micrometer resolution while the heart moves. The development of multiphoton microscopy has made in vivo, cell-resolved measurements of calcium dynamics and vascular function possible in motionless organs such as the brain. In heart, however, studies of in vivo interactions between cells and the native microenvironment are behind other organ systems. Our goal was to develop methods for intravital imaging of cardiac structural and calcium dynamics with microscopic resolution. Methods: Ventilated mice expressing GCaMP6f, a genetically encoded calcium indicator, received a thoracotomy to provide optical access to the heart. Vasculature was labeled with an injection of dextran-labeled dye. The heart was partially stabilized by a titanium probe with a glass window. Images were acquired at 30 frames per second with spontaneous heartbeat and continuously running, ventilated breathing. The data were reconstructed into three-dimensional volumes showing tissue structure, vasculature, and GCaMP6f signal in cardiomyocytes as a function of both the cardiac and respiratory cycle. Results: We demonstrated the capability to simultaneously measure calcium transients, vessel size, and tissue displacement in three dimensions with micrometer resolution. Reconstruction at various combinations of cardiac and respiratory phase enabled measurement of regional and single-cell cardiomyocyte calcium transients (GCaMP6f fluorescence). GCaMP6f fluorescence transients in individual, aberrantly firing cardiomyocytes were also quantified. Comparisons of calcium dynamics (rise-time and tau) at varying positions within the ventricle wall showed no significant depth dependence. Conclusion: This method enables studies of coupling between contraction and excitation during physiological blood perfusion and breathing at high spatiotemporal resolution. These capabilities could lead to a new understanding of normal and disease function of cardiac cells.
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Affiliation(s)
- Jason S Jones
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY, United States
| | - David M Small
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY, United States
| | - Nozomi Nishimura
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY, United States
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31
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Kuo WC, Kuo YM, Syu JP, Wang HL, Lai CM, Chen JW, Lo YC, Chen YY. The use of intensity-based Doppler variance method for single vessel response to functional neurovascular activation. JOURNAL OF BIOPHOTONICS 2018; 11:e201800017. [PMID: 29688625 DOI: 10.1002/jbio.201800017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Accepted: 04/19/2018] [Indexed: 05/09/2023]
Abstract
This study presents 1 use of optical coherence tomography (OCT) angiography technique to examine neurovascular coupling effect. Repeated B-scans OCT recording is performed on the rat somatosensory cortex with cranial window preparation while its contralateral forepaw is electrically stimulated to activate the neurons in rest. We use an intensity-based Doppler variance (IBDV) algorithm mapped cerebral blood vessels in the cortex, and the temporal alteration in blood perfusion during neurovascular activation is analyzed using the proposed IBDV quantitative parameters. By using principal component analysis-based Fuzzy C Means clustering method, the stimulus-evoked vasomotion patterns were classified into 3 categories. We found that the response time of small vessels (resting diameter 14.9 ±6.6 μm), middle vessels (resting diameter 21.1 ±7.9 μm) and large vessels (resting diameter 50.7 ±6.5 μm) to achieve 5% change of vascular dilation after stimulation was 1.5, 2 and 5.5 seconds, respectively. Approximately 5% peak change of relative blood flow (RBF) in both small and middle vessels was observed. The large vessels react slowly and their responses nearly 4 seconds delayed, but no significant change in RBF of the large vessels was seen.
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Affiliation(s)
- Wen-Chuan Kuo
- Institute of Biophotonics, National Yang-Ming University, Taipei, Taiwan
| | - Yue-Ming Kuo
- Institute of Biophotonics, National Yang-Ming University, Taipei, Taiwan
| | - Jia-Pu Syu
- Institute of Biophotonics, National Yang-Ming University, Taipei, Taiwan
| | - Han-Lin Wang
- Department of Biomedical Engineering, National Yang-Ming University, Taipei, Taiwan
| | - Chi-Ming Lai
- Department of Electronic Engineering, Ming-Chuan University, Taoyuan, Taiwan
| | - Jia-Wei Chen
- Department of Biomedical Engineering, National Yang-Ming University, Taipei, Taiwan
| | - Yu-Chun Lo
- The Ph.D. Program for Neural Regenerative Medicine, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan
| | - You-Yin Chen
- Department of Biomedical Engineering, National Yang-Ming University, Taipei, Taiwan
- The Ph.D. Program for Neural Regenerative Medicine, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan
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32
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Li Y, Choi WJ, Wei W, Song S, Zhang Q, Liu J, Wang RK. Aging-associated changes in cerebral vasculature and blood flow as determined by quantitative optical coherence tomography angiography. Neurobiol Aging 2018; 70:148-159. [PMID: 30007164 DOI: 10.1016/j.neurobiolaging.2018.06.017] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 06/14/2018] [Accepted: 06/14/2018] [Indexed: 01/29/2023]
Abstract
Normal aging is associated with significant alterations in brain's vascular structure and function, which can lead to compromised cerebral circulation and increased risk of neurodegeneration. The in vivo examination of cerebral blood flow (CBF), including capillary beds, in aging brains with sufficient spatial detail remains challenging with current imaging modalities. In the present study, we use 3-dimensional (3-D) quantitative optical coherence tomography angiography (OCTA) to examine characteristic differences of the cerebral vasculatures and hemodynamics at the somatosensory cortex between old (16 months old) and young mice (2 months old) in vivo. The quantitative metrics include cortical vascular morphology, CBF, and capillary flow velocity. We show that compared with young mice, the pial arterial tortuosity increases by 14%, the capillary vessel density decreases by 15%, and the CBF reduces by 33% in the old mice. Most importantly, changes in capillary velocity and heterogeneity with aging are quantified for the first time with sufficiently high statistical power between young and old populations, with a 21% (p < 0.05) increase in capillary mean velocity and 19% (p ≤ 0.05) increase in velocity heterogeneity in the latter. Our findings through noninvasive imaging are in line with previous studies of vascular structure modification with aging, with additional quantitative assessment in capillary velocity enabled by advanced OCTA algorithms on a single imaging platform. The results offer OCTA as a promising neuroimaging tool to study vascular aging, which may shed new light on the investigations of vascular factors contributing to the pathophysiology of age-related neurodegenerative disorders.
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Affiliation(s)
- Yuandong Li
- Department of Bioengineering, College of Engineering and School of Medicine, University of Washington, Seattle, WA, USA
| | - Woo June Choi
- Department of Bioengineering, College of Engineering and School of Medicine, University of Washington, Seattle, WA, USA; School of Electrical and Electronics Engineering, College of ICT Engineering, Chung-Ang University, Seoul, Korea
| | - Wei Wei
- Department of Bioengineering, College of Engineering and School of Medicine, University of Washington, Seattle, WA, USA
| | - Shaozhen Song
- Department of Bioengineering, College of Engineering and School of Medicine, University of Washington, Seattle, WA, USA
| | - Qinqin Zhang
- Department of Bioengineering, College of Engineering and School of Medicine, University of Washington, Seattle, WA, USA
| | - Jialing Liu
- Department of Neurological Surgery, University of California, San Francisco and SFVAMC, San Francisco, CA, USA
| | - Ruikang K Wang
- Department of Bioengineering, College of Engineering and School of Medicine, University of Washington, Seattle, WA, USA.
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33
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Moeini M, Lu X, Avti PK, Damseh R, Bélanger S, Picard F, Boas D, Kakkar A, Lesage F. Compromised microvascular oxygen delivery increases brain tissue vulnerability with age. Sci Rep 2018; 8:8219. [PMID: 29844478 PMCID: PMC5974237 DOI: 10.1038/s41598-018-26543-w] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 05/16/2018] [Indexed: 11/22/2022] Open
Abstract
Despite the possible role of impaired cerebral tissue oxygenation in age-related cognition decline, much is still unknown about the changes in brain tissue pO2 with age. Using a detailed investigation of the age-related changes in cerebral tissue oxygenation in the barrel cortex of healthy, awake aged mice, we demonstrate decreased arteriolar and tissue pO2 with age. These changes are exacerbated after middle-age. We further uncovered evidence of the presence of hypoxic micro-pockets in the cortex of awake old mice. Our data suggests that from young to middle-age, a well-regulated capillary oxygen supply maintains the oxygen availability in cerebral tissue, despite decreased tissue pO2 next to arterioles. After middle-age, due to decreased hematocrit, reduced capillary density and higher capillary transit time heterogeneity, the capillary network fails to compensate for larger decreases in arterial pO2. The substantial decrease in brain tissue pO2, and the presence of hypoxic micro-pockets after middle-age are of significant importance, as these factors may be related to cognitive decline in elderly people.
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Affiliation(s)
- Mohammad Moeini
- Biomedical Engineering Institute, École Polytechnique de Montréal, Montréal, QC, Canada.,Research Center of Montreal Heart Institute, Montréal, QC, Canada.,Department of Chemistry, McGill University, Montréal, QC, Canada
| | - Xuecong Lu
- Biomedical Engineering Institute, École Polytechnique de Montréal, Montréal, QC, Canada.,Research Center of Montreal Heart Institute, Montréal, QC, Canada
| | - Pramod K Avti
- Biomedical Engineering Institute, École Polytechnique de Montréal, Montréal, QC, Canada.,Research Center of Montreal Heart Institute, Montréal, QC, Canada.,Department of Biophysics, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Rafat Damseh
- Biomedical Engineering Institute, École Polytechnique de Montréal, Montréal, QC, Canada
| | - Samuel Bélanger
- Biomedical Engineering Institute, École Polytechnique de Montréal, Montréal, QC, Canada.,Research Center of Montreal Heart Institute, Montréal, QC, Canada
| | - Frédéric Picard
- Centre de Recherche de l'Institut Universitaire de Cardiologie et Pneumologie de Québec (IUCPQ), Québec, QC, Canada
| | - David Boas
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA.,Biomedical Engineering Department, College of Engineering, Boston University, Boston, MA, USA
| | - Ashok Kakkar
- Department of Chemistry, McGill University, Montréal, QC, Canada
| | - Frédéric Lesage
- Biomedical Engineering Institute, École Polytechnique de Montréal, Montréal, QC, Canada. .,Research Center of Montreal Heart Institute, Montréal, QC, Canada.
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LIU XUAN, ZAKI FARZANA, RENAUD DYLAN. Assessment and removal of additive noise in a complex optical coherence tomography signal based on Doppler variation analysis. APPLIED OPTICS 2018; 57:2873-2880. [PMID: 29714288 PMCID: PMC6036923 DOI: 10.1364/ao.57.002873] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Accepted: 03/12/2018] [Indexed: 05/30/2023]
Abstract
In this study, we investigate and validate a novel approach to assess and remove additive noise for optical coherence tomography (OCT) imaging. Our method first generates a map of additive noise for the OCT image through Doppler variation analysis. We then remove the additive noise from the real and imaginary parts of the complex OCT signal through pixelwise Wiener filtering. Our results show that the method described in this manuscript improves the sensitivity of OCT imaging and preserves the spatial resolution without the need to modify the imaging apparatus and data acquisition protocol.
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Affiliation(s)
- XUAN LIU
- Department of Electrical and Computer Engineering, New Jersey Institute of Technology, Newark, NJ 07102
| | - FARZANA ZAKI
- Department of Electrical and Computer Engineering, New Jersey Institute of Technology, Newark, NJ 07102
| | - DYLAN RENAUD
- Department of Physics, New Jersey Institute of Technology, Newark, NJ 07102
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35
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Tan B, MacLellan B, Mason E, Bizheva K. Structural, functional and blood perfusion changes in the rat retina associated with elevated intraocular pressure, measured simultaneously with a combined OCT+ERG system. PLoS One 2018; 13:e0193592. [PMID: 29509807 PMCID: PMC5839563 DOI: 10.1371/journal.pone.0193592] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Accepted: 02/14/2018] [Indexed: 02/07/2023] Open
Abstract
Acute elevation of intraocular pressure (IOP) to ischemic and non-ischemic levels can cause temporary or permanent changes in the retinal morphology, function and blood flow/blood perfusion. Previously, such changes in the retina were assessed separately with different methods in clinical studies and animal models. In this study, we used a combined OCT+ ERG system in combination with Doppler OCT and OCT angiography (OCTA) imaging protocols, in order to evaluate simultaneously and correlate changes in the retinal morphology, the retinal functional response to visual stimulation, and the retinal blood flow/blood perfusion, associated with IOP elevation to ischemic and non-ischemic levels in rats. Results from this study suggest that the inner retina responds faster to IOP elevation to levels greater than 30 mmHg with significant reduction of the total retinal blood flow (TRBF), decrease of the capillaries’ perfusion and reduction of the ON bipolar cells contribution to the ERG traces. Furthermore, this study showed that ischemic levels of IOP elevation cause an additional significant decrease in the ERG photoreceptor response in the posterior retina. Thirty minutes after IOP normalization, retinal morphology, blood flow and blood perfusion recovered to baseline values, while retinal function did not recover completely.
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Affiliation(s)
- Bingyao Tan
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario, Canada
| | - Benjamin MacLellan
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario, Canada
| | - Erik Mason
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario, Canada
| | - Kostadinka Bizheva
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario, Canada
- School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada
- Department of System Design Engineering, University of Waterloo, Waterloo, Ontario, Canada
- * E-mail:
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36
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Liu R, Winkelmann JA, Spicer G, Zhu Y, Eid A, Ameer GA, Backman V, Yi J. Single capillary oximetry and tissue ultrastructural sensing by dual-band dual-scan inverse spectroscopic optical coherence tomography. LIGHT, SCIENCE & APPLICATIONS 2018; 7:57. [PMID: 30839641 PMCID: PMC6113297 DOI: 10.1038/s41377-018-0057-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 08/03/2018] [Accepted: 08/03/2018] [Indexed: 05/03/2023]
Abstract
Measuring capillary oxygenation and the surrounding ultrastructure can allow one to monitor a microvascular niche and better understand crucial biological mechanisms. However, capillary oximetry and pericapillary ultrastructure are challenging to measure in vivo. Here we demonstrate a novel optical imaging system, dual-band dual-scan inverse spectroscopic optical coherence tomography (D2-ISOCT), that, for the first time, can simultaneously obtain the following metrics in vivo using endogenous contrast: (1) capillary-level oxygen saturation and arteriolar-level blood flow rates, oxygen delivery rates, and oxygen metabolic rates; (2) spatial characteristics of tissue structures at length scales down to 30 nm; and (3) morphological images up to 2 mm in depth. To illustrate the capabilities of D2-ISOCT, we monitored alterations to capillaries and the surrounding pericapillary tissue (tissue between the capillaries) in the healing response of a mouse ear wound model. The obtained microvascular and ultrastructural metrics corroborated well with each other, showing the promise of D2-ISOCT for becoming a powerful new non-invasive imaging tool.
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Affiliation(s)
- Rongrong Liu
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208 USA
| | - James A. Winkelmann
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208 USA
| | - Graham Spicer
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL 60208 USA
| | - Yunxiao Zhu
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208 USA
| | - Aya Eid
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208 USA
| | - Guillermo A. Ameer
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208 USA
| | - Vadim Backman
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208 USA
| | - Ji Yi
- Department of Medicine, Boston University School of Medicine, Boston, MA 02118 USA
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Shi W, Gao W, Chen C, Yang VXD. Differential standard deviation of log-scale intensity based optical coherence tomography angiography. JOURNAL OF BIOPHOTONICS 2017; 10:1597-1606. [PMID: 28133932 DOI: 10.1002/jbio.201600264] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 12/25/2016] [Accepted: 01/12/2017] [Indexed: 05/08/2023]
Abstract
In this paper, a differential standard deviation of log-scale intensity (DSDLI) based optical coherence tomography angiography (OCTA) is presented for calculating microvascular images of human skin. The DSDLI algorithm calculates the variance in difference images of two consecutive log-scale intensity based structural images from the same position along depth direction to contrast blood flow. The en face microvascular images were then generated by calculating the standard deviation of the differential log-scale intensities within the specific depth range, resulting in an improvement in spatial resolution and SNR in microvascular images compared to speckle variance OCT and power intensity differential method. The performance of DSDLI was testified by both phantom and in vivo experiments. In in vivo experiments, a self-adaptive sub-pixel image registration algorithm was performed to remove the bulk motion noise, where 2D Fourier transform was utilized to generate new images with spatial interval equal to half of the distance between two pixels in both fast-scanning and depth directions. The SNRs of signals of flowing particles are improved by 7.3 dB and 6.8 dB on average in phantom and in vivo experiments, respectively, while the average spatial resolution of images of in vivo blood vessels is increased by 21%.
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Affiliation(s)
- Weisong Shi
- Nanjing University of Science and Technology, Department of Optical Engineering, Nanjing, Jiangsu, China
| | - Wanrong Gao
- Nanjing University of Science and Technology, Department of Optical Engineering, Nanjing, Jiangsu, China
| | - Chaoliang Chen
- Ryerson University, Department of Electrical and Computer Engineering, Biophotonics and Bioengineering Lab, Toronto, Ontario, Canada
| | - Victor X D Yang
- Ryerson University, Department of Electrical and Computer Engineering, Biophotonics and Bioengineering Lab, Toronto, Ontario, Canada
- Sunnybrook Health Sciences Centre, Division of Neurosurgery, Toronto, Ontario, Canada
- University of Toronto, Division of Neurosurgery, Faculty of Medicine, Toronto, Ontario, Canada
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Gagnon L, Sakadžić S, Lesage F, Pouliot P, Dale AM, Devor A, Buxton RB, Boas DA. Validation and optimization of hypercapnic-calibrated fMRI from oxygen-sensitive two-photon microscopy. Philos Trans R Soc Lond B Biol Sci 2017; 371:rstb.2015.0359. [PMID: 27574311 DOI: 10.1098/rstb.2015.0359] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/13/2016] [Indexed: 01/30/2023] Open
Abstract
Hypercapnic-calibrated fMRI allows the estimation of the relative changes in the cerebral metabolic rate of oxygen (rCMRO2) from combined BOLD and arterial spin labelling measurements during a functional task, and promises to permit more quantitative analyses of brain activity patterns. The estimation relies on a macroscopic model of the BOLD effect that balances oxygen delivery and consumption to predict haemoglobin oxygenation and the BOLD signal. The accuracy of calibrated fMRI approaches has not been firmly established, which is limiting their broader adoption. We use our recently developed microscopic vascular anatomical network model in mice as a ground truth simulator to test the accuracy of macroscopic, lumped-parameter BOLD models. In particular, we investigate the original Davis model and a more recent heuristic simplification. We find that these macroscopic models are inaccurate using the originally defined parameters, but that the accuracy can be significantly improved by redefining the model parameters to take on new values. In particular, we find that the parameter α that relates cerebral blood-volume changes to cerebral blood-flow changes is significantly smaller than typically assumed and that the optimal value changes with magnetic field strength. The results are encouraging in that they support the use of simple BOLD models to quantify BOLD signals, but further work is needed to understand the physiological interpretation of the redefined model parameters.This article is part of the themed issue 'Interpreting BOLD: a dialogue between cognitive and cellular neuroscience'.
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Affiliation(s)
- Louis Gagnon
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA Department of Medicine, Laval University, Quebec City, Quebec, Canada Deparment of Electrical Engineering, École Polytechnique Montreal, Montreal, Quebec, Canada
| | - Sava Sakadžić
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Frédéric Lesage
- Deparment of Electrical Engineering, École Polytechnique Montreal, Montreal, Quebec, Canada
| | - Philippe Pouliot
- Deparment of Electrical Engineering, École Polytechnique Montreal, Montreal, Quebec, Canada
| | - Anders M Dale
- Department of Neurosciences and Radiology, UCSD, La Jolla, CA, USA
| | - Anna Devor
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA Department of Neurosciences and Radiology, UCSD, La Jolla, CA, USA
| | | | - David A Boas
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
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Zhu J, Zhang B, Qi L, Wang L, Yang Q, Zhu Z, Huo T, Chen Z. Quantitative angle-insensitive flow measurement using relative standard deviation OCT. APPLIED PHYSICS LETTERS 2017; 111:181101. [PMID: 29151604 PMCID: PMC5663647 DOI: 10.1063/1.5009200] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Accepted: 10/13/2017] [Indexed: 05/09/2023]
Abstract
Incorporating different data processing methods, optical coherence tomography (OCT) has the ability for high-resolution angiography and quantitative flow velocity measurements. However, OCT angiography cannot provide quantitative information of flow velocities, and the velocity measurement based on Doppler OCT requires the determination of Doppler angles, which is a challenge in a complex vascular network. In this study, we report on a relative standard deviation OCT (RSD-OCT) method which provides both vascular network mapping and quantitative information for flow velocities within a wide range of Doppler angles. The RSD values are angle-insensitive within a wide range of angles, and a nearly linear relationship was found between the RSD values and the flow velocities. The RSD-OCT measurement in a rat cortex shows that it can quantify the blood flow velocities as well as map the vascular network in vivo.
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Affiliation(s)
- Jiang Zhu
- Beckman Laser Institute, University of California, Irvine, Irvine, California 92612, USA
| | | | - Li Qi
- Beckman Laser Institute, University of California, Irvine, Irvine, California 92612, USA
| | | | - Qiang Yang
- Beckman Laser Institute, University of California, Irvine, Irvine, California 92612, USA
| | | | - Tiancheng Huo
- Beckman Laser Institute, University of California, Irvine, Irvine, California 92612, USA
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40
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Mokbul MI. Optical Coherence Tomography: Basic Concepts and Applications in Neuroscience Research. J Med Eng 2017; 2017:3409327. [PMID: 29214158 PMCID: PMC5682075 DOI: 10.1155/2017/3409327] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Revised: 06/22/2017] [Accepted: 09/14/2017] [Indexed: 12/28/2022] Open
Abstract
Optical coherence tomography is a micrometer-scale imaging modality that permits label-free, cross-sectional imaging of biological tissue microstructure using tissue backscattering properties. After its invention in the 1990s, OCT is now being widely used in several branches of neuroscience as well as other fields of biomedical science. This review study reports an overview of OCT's applications in several branches or subbranches of neuroscience such as neuroimaging, neurology, neurosurgery, neuropathology, and neuroembryology. This study has briefly summarized the recent applications of OCT in neuroscience research, including a comparison, and provides a discussion of the remaining challenges and opportunities in addition to future directions. The chief aim of the review study is to draw the attention of a broad neuroscience community in order to maximize the applications of OCT in other branches of neuroscience too, and the study may also serve as a benchmark for future OCT-based neuroscience research. Despite some limitations, OCT proves to be a useful imaging tool in both basic and clinical neuroscience research.
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Affiliation(s)
- Mobin Ibne Mokbul
- Notre Dame College, Motijheel Circular Road, Arambagh, Motijheel, Dhaka 1000, Bangladesh
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41
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Tang J, Erdener SE, Fu B, Boas DA. Capillary red blood cell velocimetry by phase-resolved optical coherence tomography. OPTICS LETTERS 2017; 42:3976-3979. [PMID: 28957175 PMCID: PMC5972360 DOI: 10.1364/ol.42.003976] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Accepted: 09/05/2017] [Indexed: 05/05/2023]
Abstract
We present a phase-resolved optical coherence tomography (OCT) method to extend Doppler OCT for the accurate measurement of the red blood cell (RBC) velocity in cerebral capillaries. OCT data were acquired with an M-mode scanning strategy (repeated A-scans) to account for the single-file passage of RBCs in a capillary, which were then high-pass filtered to remove the stationary component of the signal to ensure an accurate measurement of phase shift of flowing RBCs. The angular frequency of the signal from flowing RBCs was then quantified from the dynamic component of the signal and used to calculate the axial speed of flowing RBCs in capillaries. We validated our measurement by RBC passage velocimetry using the signal magnitude of the same OCT time series data.
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Affiliation(s)
- Jianbo Tang
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts 02129, USA
| | - Sefik Evren Erdener
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts 02129, USA
| | - Buyin Fu
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts 02129, USA
| | - David A. Boas
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts 02129, USA
- Neurophotonics Center, Department of Biomedical Engineering, Boston University, Boston, Massachusetts 02215, USA
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Urban A, Golgher L, Brunner C, Gdalyahu A, Har-Gil H, Kain D, Montaldo G, Sironi L, Blinder P. Understanding the neurovascular unit at multiple scales: Advantages and limitations of multi-photon and functional ultrasound imaging. Adv Drug Deliv Rev 2017; 119:73-100. [PMID: 28778714 DOI: 10.1016/j.addr.2017.07.018] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 07/17/2017] [Accepted: 07/22/2017] [Indexed: 02/07/2023]
Abstract
Developing efficient brain imaging technologies by combining a high spatiotemporal resolution and a large penetration depth is a key step for better understanding the neurovascular interface that emerges as a main pathway to neurodegeneration in many pathologies such as dementia. This review focuses on the advances in two complementary techniques: multi-photon laser scanning microscopy (MPLSM) and functional ultrasound imaging (fUSi). MPLSM has become the gold standard for in vivo imaging of cellular dynamics and morphology, together with cerebral blood flow. fUSi is an innovative imaging modality based on Doppler ultrasound, capable of recording vascular brain activity over large scales (i.e., tens of cubic millimeters) at unprecedented spatial and temporal resolution for such volumes (up to 10μm pixel size at 10kHz). By merging these two technologies, researchers may have access to a more detailed view of the various processes taking place at the neurovascular interface. MPLSM and fUSi are also good candidates for addressing the major challenge of real-time delivery, monitoring, and in vivo evaluation of drugs in neuronal tissue.
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Affiliation(s)
- Alan Urban
- Neuroelectronics Research Flanders, Leuven, Belgium; VIB, Leuven, Belgium and/or IMEC, Leuven, Belgium; Department of Neurosciences, KU Leuven, Leuven, Belgium; Neurobiology Dept., Wise Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel
| | - Lior Golgher
- Sagol School of Neuroscience, Tel-Aviv University, Tel-Aviv, Israel
| | - Clément Brunner
- Neuroelectronics Research Flanders, Leuven, Belgium; VIB, Leuven, Belgium and/or IMEC, Leuven, Belgium
| | - Amos Gdalyahu
- Neurobiology Dept., Wise Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel
| | - Hagai Har-Gil
- Sagol School of Neuroscience, Tel-Aviv University, Tel-Aviv, Israel
| | - David Kain
- Neurobiology Dept., Wise Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel
| | - Gabriel Montaldo
- Neuroelectronics Research Flanders, Leuven, Belgium; VIB, Leuven, Belgium and/or IMEC, Leuven, Belgium
| | - Laura Sironi
- Physics Dept., Universita degli Studi di Milano Bicocca, Italy
| | - Pablo Blinder
- Neurobiology Dept., Wise Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel; Sagol School of Neuroscience, Tel-Aviv University, Tel-Aviv, Israel.
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Zhu J, Merkle CW, Bernucci MT, Chong SP, Srinivasan VJ. Can OCT Angiography Be Made a Quantitative Blood Measurement Tool? APPLIED SCIENCES-BASEL 2017; 7. [PMID: 30009045 PMCID: PMC6042878 DOI: 10.3390/app7070687] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Optical Coherence Tomography Angiography (OCTA) refers to a powerful class of OCT scanning protocols and algorithms that selectively enhance the imaging of blood vessel lumens, based mainly on the motion and scattering of red blood cells (RBCs). Though OCTA is widely used in clinical and basic science applications for visualization of perfused blood vessels, OCTA is still primarily a qualitative tool. However, more quantitative hemodynamic information would better delineate disease mechanisms, and potentially improve the sensitivity for detecting early stages of disease. Here, we take a broader view of OCTA in the context of microvascular hemodynamics and light scattering. Paying particular attention to the unique challenges presented by capillaries versus larger supplying and draining vessels, we critically assess opportunities and challenges in making OCTA a quantitative tool.
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Affiliation(s)
- Jun Zhu
- Department of Biomedical Engineering, University of California Davis, Davis, CA 95616, USA
| | - Conrad W. Merkle
- Department of Biomedical Engineering, University of California Davis, Davis, CA 95616, USA
| | - Marcel T. Bernucci
- Department of Biomedical Engineering, University of California Davis, Davis, CA 95616, USA
| | - Shau Poh Chong
- Department of Biomedical Engineering, University of California Davis, Davis, CA 95616, USA
| | - Vivek J. Srinivasan
- Department of Biomedical Engineering, University of California Davis, Davis, CA 95616, USA
- Department of Ophthalmology and Vision Science, School of Medicine, University of California Davis, Sacramento, CA 95817, USA
- Correspondence: ; Tel.: +1-530-752-9277
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44
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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.
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45
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Wang RK, Zhang Q, Li Y, Song S. Optical coherence tomography angiography-based capillary velocimetry. JOURNAL OF BIOMEDICAL OPTICS 2017; 22:66008. [PMID: 28617921 PMCID: PMC5472241 DOI: 10.1117/1.jbo.22.6.066008] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Accepted: 05/19/2017] [Indexed: 05/05/2023]
Abstract
Challenge persists in the field of optical coherence tomography (OCT) when it is required to quantify capillary blood flow within tissue beds in vivo. We propose a useful approach to statistically estimate the mean capillary flow velocity using a model-based statistical method of eigendecomposition (ED) analysis of the complex OCT signals obtained with the OCT angiography (OCTA) scanning protocol. ED-based analysis is achieved by the covariance matrix of the ensemble complex OCT signals, upon which the eigenvalues and eigenvectors that represent the subsets of the signal makeup are calculated. From this analysis, the signals due to moving particles can be isolated by employing an adaptive regression filter to remove the eigencomponents that represent static tissue signals. The mean frequency (MF) of moving particles can be estimated by the first lag-one autocorrelation of the corresponding eigenvectors. Three important parameters are introduced, including the blood flow signal power representing the presence of blood flow (i.e., OCTA signals), the MF indicating the mean velocity of blood flow, and the frequency bandwidth describing the temporal flow heterogeneity within a scanned tissue volume. The proposed approach is tested using scattering phantoms, in which microfluidic channels are used to simulate the functional capillary vessels that are perfused with the scattering intralipid solution. The results indicate a linear relationship between the MF and mean flow velocity. In vivo animal experiments are also conducted by imaging mouse brain with distal middle cerebral artery ligation to test the capability of the method to image the changes in capillary flows in response to an ischemic insult, demonstrating the practical usefulness of the proposed method for providing important quantifiable information about capillary tissue beds in the investigations of neurological conditions in vivo.
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Affiliation(s)
- Ruikang K. Wang
- University of Washington, Department of Bioengineering, Seattle, Washington, United States
- University of Washington, Department of Ophthalmology, Seattle, Washington, United States
- Address all correspondence to: Ruikang K. Wang, E-mail:
| | - Qinqin Zhang
- University of Washington, Department of Bioengineering, Seattle, Washington, United States
| | - Yuandong Li
- University of Washington, Department of Bioengineering, Seattle, Washington, United States
| | - Shaozhen Song
- University of Washington, Department of Bioengineering, Seattle, Washington, United States
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Lee B, Novais EA, Waheed NK, Adhi M, de Carlo TE, Cole ED, Moult EM, Choi W, Lane M, Baumal CR, Duker JS, Fujimoto JG. En Face Doppler Optical Coherence Tomography Measurement of Total Retinal Blood Flow in Diabetic Retinopathy and Diabetic Macular Edema. JAMA Ophthalmol 2017; 135:244-251. [PMID: 28196198 DOI: 10.1001/jamaophthalmol.2016.5774] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Importance Alterations in ocular blood flow play an important role in the pathogenesis and progression of diabetic retinopathy (DR). However, the measurement of retinal blood flow in clinical studies has been challenging. En face Doppler optical coherence tomography (OCT) provides an effective method for measuring total retinal blood flow (TRBF) in the clinic. Objective To investigate TRBF in eyes with DR of varying severity, with or without diabetic macular edema (DME), using en face Doppler OCT. Design, Setting, and Participants This was a cross-sectional study conducted from May 23, 2014, to January 11, 2016, which analyzed 41 eyes with DR from 31 diabetic patients, 20 eyes without DR from 11 diabetic patients, and 16 eyes from 12 healthy age-matched controls, all at the New England Eye Center in Boston, Massachusetts. Main Outcomes and Measures Participants were imaged with a high-speed, swept-source OCT prototype at 1050-nm wavelength using repeated en face Doppler OCT raster scans, comprising 600 × 80 axial scans and covering a 1.5 × 2-mm2 area centered at the optic disc. The TRBF was automatically calculated using custom Matlab software. Results This study included 41 eyes with DR from 31 diabetic patients (mean [SD] age, 62.8 [13.4] years; 12 were female patients), 20 eyes without DR from 11 diabetic patients (mean [SD] age, 58.8 [10.1] years; 5 were female patients), and 16 eyes from 12 healthy age-matched controls (mean [SD] age, 57.9 [8.1] years; 8 were female participants). The mean (SD) TRBF was 28.0 (8.5) µL/min in the eyes with DME, 48.8 (13.4) µL/min in the eyes with DR but without DME, 40.1 (7.7) µL/min in the diabetic eyes without retinopathy, and 44.4 (8.3) µL/min in age-matched healthy eyes. A difference in TRBF between the eyes with DME that were treated and the eyes with DME that were not treated was not identified. The TRBF was consistently low in the eyes with DME regardless of DR severity. The eyes with moderate nonproliferative DR but without DME exhibited a wide range of TRBF from 31.1 to 75.0 µL/min, with the distribution being highly skewed. Conclusions and Relevance High-speed en face Doppler OCT can measure TRBF in healthy and diabetic eyes. Diabetic eyes with DME exhibited lower TRBF than healthy eyes (P ≤ .001). Further longitudinal studies of TRBF in eyes with DR would be helpful to determine whether reduced TRBF is a risk factor for DME.
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Affiliation(s)
- ByungKun Lee
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge2Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge
| | - Eduardo A Novais
- New England Eye Center, Tufts Medical Center, Boston, Massachusetts4Federal University of São Paulo, School of Medicine, São Paulo, Brazil
| | - Nadia K Waheed
- New England Eye Center, Tufts Medical Center, Boston, Massachusetts
| | - Mehreen Adhi
- New England Eye Center, Tufts Medical Center, Boston, Massachusetts
| | | | - Emily D Cole
- New England Eye Center, Tufts Medical Center, Boston, Massachusetts
| | - Eric M Moult
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge2Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge
| | - WooJhon Choi
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge2Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge
| | - Mark Lane
- New England Eye Center, Tufts Medical Center, Boston, Massachusetts5Queen Elizabeth Hospital Birmingham, University Hospitals Birmingham NHS Foundation Trust, Birmingham, England
| | | | - Jay S Duker
- New England Eye Center, Tufts Medical Center, Boston, Massachusetts
| | - James G Fujimoto
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge2Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge
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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.
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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
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Li L, Zhu L, Ma C, Lin L, Yao J, Wang L, Maslov K, Zhang R, Chen W, Shi J, Wang LV. Single-impulse Panoramic Photoacoustic Computed Tomography of Small-animal Whole-body Dynamics at High Spatiotemporal Resolution. Nat Biomed Eng 2017; 1:0071. [PMID: 29333331 PMCID: PMC5766044 DOI: 10.1038/s41551-017-0071] [Citation(s) in RCA: 244] [Impact Index Per Article: 34.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2016] [Accepted: 03/30/2017] [Indexed: 01/05/2023]
Abstract
Imaging of small animals has played an indispensable role in preclinical research by providing high dimensional physiological, pathological, and phenotypic insights with clinical relevance. Yet pure optical imaging suffers from either shallow penetration (up to ~1-2 mm) or a poor depth-to-resolution ratio (~1/3), and non-optical techniques for whole-body imaging of small animals lack either spatiotemporal resolution or functional contrast. Here, we demonstrate that standalone single-impulse photoacoustic computed tomography (SIP-PACT) mitigates these limitations by combining high spatiotemporal resolution (125-µm in-plane resolution, 50 µs / frame data acquisition and 50-Hz frame rate), deep penetration (48-mm cross-sectional width in vivo), anatomical, dynamical and functional contrasts, and full-view fidelity. By using SIP-PACT, we imaged in vivo whole-body dynamics of small animals in real time and obtained clear sub-organ anatomical and functional details. We tracked unlabeled circulating melanoma cells and imaged the vasculature and functional connectivity of whole rat brains. SIP-PACT holds great potential for both pre-clinical imaging and clinical translation.
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Affiliation(s)
- Lei Li
- Department of Electrical and Systems Engineering, Washington University in St. Louis, One Brookings Dr., St. Louis, MO, 63130
- Department of Medical Engineering, California Institute of Technology, 1200 E California Blvd., Pasadena, CA 91125
| | - Liren Zhu
- Department of Medical Engineering, California Institute of Technology, 1200 E California Blvd., Pasadena, CA 91125
- Department of Biomedical Engineering, Washington University in St. Louis, One Brookings Dr., St. Louis, MO, 63130
| | - Cheng Ma
- Department of Biomedical Engineering, Washington University in St. Louis, One Brookings Dr., St. Louis, MO, 63130
| | - Li Lin
- Department of Medical Engineering, California Institute of Technology, 1200 E California Blvd., Pasadena, CA 91125
- Department of Biomedical Engineering, Washington University in St. Louis, One Brookings Dr., St. Louis, MO, 63130
| | - Junjie Yao
- Department of Biomedical Engineering, Washington University in St. Louis, One Brookings Dr., St. Louis, MO, 63130
| | - Lidai Wang
- Department of Biomedical Engineering, Washington University in St. Louis, One Brookings Dr., St. Louis, MO, 63130
| | - Konstantin Maslov
- Department of Medical Engineering, California Institute of Technology, 1200 E California Blvd., Pasadena, CA 91125
| | - Ruiying Zhang
- Department of Biomedical Engineering, Washington University in St. Louis, One Brookings Dr., St. Louis, MO, 63130
| | - Wanyi Chen
- Department of Biomedical Engineering, Washington University in St. Louis, One Brookings Dr., St. Louis, MO, 63130
| | - Junhui Shi
- Department of Medical Engineering, California Institute of Technology, 1200 E California Blvd., Pasadena, CA 91125
| | - Lihong V. Wang
- Department of Medical Engineering, California Institute of Technology, 1200 E California Blvd., Pasadena, CA 91125
- Department of Electrical Engineering, California Institute of Technology, 1200 E California Blvd., Pasadena, CA 91125
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Flow Measurement by Lateral Resonant Doppler Optical Coherence Tomography in the Spectral Domain. APPLIED SCIENCES-BASEL 2017. [DOI: 10.3390/app7040382] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Optical Coherence Microscopy. Methods Mol Biol 2017. [PMID: 28324609 DOI: 10.1007/978-1-4939-6810-7_12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
The present chapter aims at demonstrating the capabilities of optical coherence microscopy (OCM) for applications in biomedical imaging. We furthermore review the functional imaging capabilities of OCM focusing on lable-free optical angiography. We conclude with a section on digital wavefront control and a short outlook on future developments, in particular for contrast enhancement techniques.
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