Observation and density estimation of a large number of skin capillaries using wide-field portable video capillaroscopy and semantic segmentation

Baku Takimoto; Kotatsu Bito; Sayaka Hari; Hiroyuki Taguchi; Hideaki Haneishi

doi:10.1117/1.JBO.28.10.106003

24 October 2023 Observation and density estimation of a large number of skin capillaries using wide-field portable video capillaroscopy and semantic segmentation

Baku Takimoto, Kotatsu Bito, Sayaka Hari, Hiroyuki Taguchi, Hideaki Haneishi

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Journal of Biomedical Optics, Vol. 28, Issue 10, 106003 (October 2023). https://doi.org/10.1117/1.JBO.28.10.106003

Abstract

Significance

Skin capillaries are non-invasively observable; their structure and blood flow can reflect tissue and systemic conditions. Quantitative analysis of video-capillaroscopy images yields novel diagnostic methods. Because the capillary structure is heterogeneous, analyzing more capillaries can increase the evaluation reliability.

Aim

We developed a system that can observe and quantify numerous capillaries and verified the performance on human skin.

Approach

We developed a portable video-capillaroscope with a spatial resolution higher than 3.5 μm and a wide field of view (7.4 mm × 5.5 mm) and a method to evaluate capillary numbers and areas using U-Net. The model was trained and tested with 22 and 11 cropped images (2.4 mm × 1.9 mm) obtained from 11 participants, respectively. They were then applied to the 7.2 mm × 5.3 mm images from four participants. Segmentation results were compared to ground-truth at the pixel level and capillary-region level.

Results

Over 1000 capillaries were simultaneously observed using the proposed system. Although pixel-level segmentation performance was low [intersection over union (IoU) = 24.5%], the number and area could be estimated. These values differed among four participants and seven sites, and they changed after skin barrier destruction.

Conclusions

The proposed system allows for observing and quantifying numerous skin capillaries simultaneously, suggesting its potential for evaluating tissue and systemic conditions.

CC BY: © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 International License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Baku Takimoto, Kotatsu Bito, Sayaka Hari, Hiroyuki Taguchi, and Hideaki Haneishi "Observation and density estimation of a large number of skin capillaries using wide-field portable video capillaroscopy and semantic segmentation," Journal of Biomedical Optics 28(10), 106003 (24 October 2023). https://doi.org/10.1117/1.JBO.28.10.106003

Received: 10 March 2023; Accepted: 10 October 2023; Published: 24 October 2023

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KEYWORDS

Capillaries

Skin

Image segmentation

Image processing

Video

Red blood cells

Semantics

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