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Yu PK, Mehnert A, Dickson JB, Qambari H, Balaratnasingam C, Cringle S, Darcey D, Yu DY. Quantitative study of spatial and temporal variation in retinal capillary network perfusion in rat eye by in vivo confocal imaging. Sci Rep 2023; 13:18923. [PMID: 37919331 PMCID: PMC10622421 DOI: 10.1038/s41598-023-44480-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Accepted: 10/09/2023] [Indexed: 11/04/2023] Open
Abstract
Microvascular dysfunction is the underlying pathological process in many systemic diseases. However, investigation into its pathogenesis is impeded by the accessibility and complexity of the microvasculature within different organs, particularly for the central nervous system. The retina as an extension of the cerebrum provides a glimpse into the brain through which the microvasculature can be observed. Two major questions remain unanswered: How do the microvessels regulate spatial and temporal delivery to satisfy the varying cellular demands, and how can we quantify blood perfusion in the 3D capillary network? Here, quantitative measurements of red blood cell (RBC) speed in each vessel in the field were made in the in vivo rat retinal capillary network using an ultrafast confocal technique with fluorescently labelled RBCs. Retinal RBC speed and number were found to vary remarkably between microvessels ranging from 215 to 6641 microns per second with significant variations spatially and temporally. Overall, the RBC speed was significantly faster in the microvessels in the superficial retina than in the deep retina (estimated marginal means of 2405 ± 238.2 µm/s, 1641 ± 173.0 µm/s respectively). These observations point to a highly dynamic nature of microvasculature that is specific to its immediate cellular environment and is constantly changing.
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Affiliation(s)
- Paula Kun Yu
- Centre for Ophthalmology and Visual Science, The University of Western Australia, Perth, Australia
- Lions Eye Institute, 2 Verdun Street, Nedlands, WA, Australia
| | - Andrew Mehnert
- Centre for Ophthalmology and Visual Science, The University of Western Australia, Perth, Australia
- Lions Eye Institute, 2 Verdun Street, Nedlands, WA, Australia
| | | | - Hassanain Qambari
- Centre for Ophthalmology and Visual Science, The University of Western Australia, Perth, Australia
- Lions Eye Institute, 2 Verdun Street, Nedlands, WA, Australia
| | - Chandrakumar Balaratnasingam
- Centre for Ophthalmology and Visual Science, The University of Western Australia, Perth, Australia
- Lions Eye Institute, 2 Verdun Street, Nedlands, WA, Australia
- Department of Ophthalmology, Sir Charles Gairdner Hospital, Nedlands, WA, Australia
| | - Stephen Cringle
- Centre for Ophthalmology and Visual Science, The University of Western Australia, Perth, Australia
- Lions Eye Institute, 2 Verdun Street, Nedlands, WA, Australia
| | - Dean Darcey
- Lions Eye Institute, 2 Verdun Street, Nedlands, WA, Australia
| | - Dao-Yi Yu
- Centre for Ophthalmology and Visual Science, The University of Western Australia, Perth, Australia.
- Lions Eye Institute, 2 Verdun Street, Nedlands, WA, Australia.
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Kohata Y, Ohta M, Jin K, Anzai H. Effects of helical centerline stent vs. straight stent placement on blood flow velocity. FRONTIERS IN MEDICAL TECHNOLOGY 2023; 5:1196125. [PMID: 37333882 PMCID: PMC10272720 DOI: 10.3389/fmedt.2023.1196125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Accepted: 05/17/2023] [Indexed: 06/20/2023] Open
Abstract
As an approach to maintain patency in femoropopliteal stenting, a helical stent configuration was proposed, which showed improved patency in clinical trials. However, the effects of helical stent placement on the flow have not been quantitatively analyzed. The purpose of this study was to estimate flow velocities to quantify the influence of helical stent placement. Helical and straight stents were implanted in three healthy pigs, and the flow velocities were estimated using the time-intensity curve (TIC) in the angiography images. The angiographic images indicated thinning of the leading edge of the contrast medium through the helically deformed artery, which was not observed in the straight stent. The slower rise of the TIC peak in the helical stent indicated faster travel of this thinner edge. Arterial expansion due to stenting was observed in all cases, and the expansion rate varied according to location. All cases of helical stent implantation showed that velocity was maintained (55.0%-71.3% velocity retention), unlike for straight stent implantation (43.0%-68.0% velocity retention); however, no significant difference was observed.
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Affiliation(s)
- Yutaro Kohata
- Graduate School of Biomedical Engineering, Tohoku University, Sendai, Japan
- Biomedical Flow Dynamics Laboratory, The Institute of Fluid Science, Tohoku University, Sendai, Japan
| | - Makoto Ohta
- Biomedical Flow Dynamics Laboratory, The Institute of Fluid Science, Tohoku University, Sendai, Japan
- ELyTMaXUMI 3757, CNRS – Université de Lyon – Tohoku University, International Joint Unit, Tohoku University, Sendai, Miyagi, Japan
| | - Kazuyoshi Jin
- Graduate School of Biomedical Engineering, Tohoku University, Sendai, Japan
- Biomedical Flow Dynamics Laboratory, The Institute of Fluid Science, Tohoku University, Sendai, Japan
| | - Hitomi Anzai
- Biomedical Flow Dynamics Laboratory, The Institute of Fluid Science, Tohoku University, Sendai, Japan
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Niizawa T, Yokemura K, Kusaka T, Sugashi T, Miura I, Kawagoe K, Masamoto K. Automated capillary flow segmentation and mapping for nailfold video capillaroscopy. Microcirculation 2022; 29:e12753. [PMID: 35212076 DOI: 10.1111/micc.12753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 02/04/2022] [Accepted: 02/21/2022] [Indexed: 11/28/2022]
Abstract
OBJECTIVE This study aimed to develop an automated image analysis method for segmentation and mapping of capillary flow dynamics captured using nailfold video capillaroscopy (NVC). Methods were applied to compare capillary flow structures and dynamics between young and middle-aged healthy controls. METHODS NVC images were obtained in a resting state, and a region of the vessel in the image was extracted using a conventional U-Net neural network. The approximate length, diameter, and radius of the curvature were calculated automatically. Flow speed and its fluctuation over time were mapped using the Radon transform and frequency spectrum analysis from the kymograph image created along the vessel's centerline. RESULTS The diameter of the curve segment (14.4 μm and 13.0 μm) and the interval of two straight segments (13.7 μm and 32.1 μm) of young and middle-aged subjects, respectively, were significantly different. Faster flow was observed in older subjects (0.48 mm/sec) than in younger subjects (0.26 mm/sec). The power spectral analysis revealed a significant correlation between the high-frequency power spectrum and the flow speed. CONCLUSIONS The present method allows a spatiotemporal characterization of capillary morphology and flow dynamics with NVC, allowing a wide application such as large-scale health assessment.
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Affiliation(s)
- Tomoya Niizawa
- Faculty of Informatics and Engineering, University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo, 182-8585, Japan
| | - Kota Yokemura
- Faculty of Informatics and Engineering, University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo, 182-8585, Japan
| | - Tomoya Kusaka
- Faculty of Informatics and Engineering, University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo, 182-8585, Japan
| | - Takuma Sugashi
- Faculty of Informatics and Engineering, University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo, 182-8585, Japan.,Center for Neuroscience and Biomedical Engineering, University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo, 182-8585, Japan
| | - Ichiro Miura
- Department of Clinical Laboratory, Social Welfare Corporation Hokkaido Institutional Society Obihiro Hospital, Japan, 1-4-17, Mita, Minato City, Japan.,Department of Human Pathology, School of Medicine, Juntendo University, Japan.,NPO Mousaikekkan Kenkyukai (Japanese Capillary Research Conference), Japan
| | - Keiji Kawagoe
- NPO Mousaikekkan Kenkyukai (Japanese Capillary Research Conference), Japan.,Toku Corporation, Japan
| | - Kazuto Masamoto
- Faculty of Informatics and Engineering, University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo, 182-8585, Japan.,Center for Neuroscience and Biomedical Engineering, University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo, 182-8585, Japan
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