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Simultaneous Detection of Blood Flow Information in Deeper-Layer Blood Vessels and Capillaries Using Automatic Image Processing Technology for Visual Extraction

The Skin Care Research Laboratory of Kao Corporation (President: Michitaka Sawada) has discovered that blood flow information for vessels in the deeper layer of skin and capillaries can be detected simultaneously in videomicroscopic vascular images by use of automatic visual extraction technology.
The study results were recently published in part in Skin Research and Technology,*1 and an image obtained as part of this research has been accepted for use on the cover page of that issue.*2



A densely-arranged network formed by blood vessels tens to hundreds of micrometers in diameter and extremely fine capillaries with a diameter of less than 10 micrometers is present in skin. Blood flowing through these vessels supplies heat, nutrients, water, and oxygen, and also collects waste products. Kao has been advancing research by investigation of the various functions of this blood vessel network from the perspective of maintaining beautiful and healthy skin.

It is known that blood vessels in the deeper layer and capillaries in the surface layer of skin differ in regard to their major roles and action characteristics. These differences are considered to be closely linked with skin condition. However, it is difficult to obtain details regarding blood flow for different vessels at an identical site simultaneously, as several different instruments are needed for acquiring information present in layers that vary in depth and have constant blood flow changes. In the present study, Kao researchers attempted simultaneous detection of blood flow information using a single image.

Simultaneous analysis of blood flow information for skin as a whole and capillaries

In 2019, Kao reported development of an image-processing technology capable of specifically extracting and quantitatively measuring blood flow changes in skin capillaries.*3 By using this technology, an image of skin including capillaries is divided into separate independent hemoglobin, melanin, and shadow components, then the hemoglobin component (Figure 1, red box in center) and noise are filtered, leaving only information for capillaries.


Figure 1. Extraction of blood vessel information
at various depths from videomicroscopic image

In the present study, it was noted that all blood flow information in the skin was visible by use of videomicroscopy to view the hemoglobin component image. Thus, it was considered that by integration of the brightness values in the image, blood flow could be estimated. As the capillaries accounted for a small percentage in the visualized portion, the hemoglobin component was considered to mainly demonstrate blood flow in the deeper layer and used for estimation.
With this technique, it is now possible to simultaneously obtain capillary blood flow information as well as that in the entire skin area by examining a single image.

Use of heat and carbonic acid with different action characteristics for evaluation of vascular image analysis technology

Skin vessels are generally considered to have two major roles. One is in regard to heat transportation for regulating body temperature, which mainly involves blood flow in vessels in the deeper layer, while the other is related to material exchange, such as the supply of nutrients and oxygen, and removal of carbon dioxide, in which capillaries in the surface layer are primarily involved. To evaluate the proposed image analysis technology, heat and carbon dioxide (carbonic acid), which have different action mechanisms, were used to quantify and compare blood flow changes in vessels at different depths.

Skin of the inner part of the upper arm in 6 Japanese male and female subjects was sequentially treated with heat and carbonic acid.*4 Images of the skin areas after each treatment were obtained and subjected to the above-mentioned image processing method for analyzing the amount of the hemoglobin component and capillary blood flow (Figure 2).
The results showed that when exposed to heat, the hemoglobin component level increased and blood flow throughout the skin was also increased, whereas nearly no changes were seen in the capillaries. Meanwhile, following exposure to carbonic acid, both the hemoglobin component throughout the skin and capillary blood flow volume were increased (Figure 3, 4). These results support previous findings indicating that heat and carbonic treatment have different characteristic actions on blood vessels.

  • * 4 Based on previously reported findings, exposure time for peak blood circulation promotion was set individually for heat and carbonic treatments. Carbonic treatment (32˚C, carbon dioxide concentration 1200 ppm, time 2 minutes). Heat treatment (41˚C, 5 minutes).

These findings indicate that this image analysis technology can provide simultaneous evaluation of blood flow information from different blood vessels using a single image.


Figure 2. Skin images after blood circulation promotion and results of image analysis


Figure 3. Changes in hemoglobin level following treatment by carbonic acid and heat


Figure 4. Changes in skin capillary score following treatment by carbonic acid and heat


Development of this non-invasive and simple technique of image analysis provides an ability to simultaneously obtain blood flow information for both capillaries and vessels in the deeper layer of an identical site. This makes it possible to extensively investigate the relationship of blood flow at various depths with skin condition, as well as the effects of various approaches to promote blood circulation.

In the future, Kao plans to further study blood flow changes brought about by aging and environmental factors, and the effects of blood flow status on various skin conditions.

About Kao

Kao creates high-value-added products that enrich the lives of consumers around the world. Through its portfolio of over 20 leading brands such as Attack, Bioré, Goldwell, Jergens, John Frieda, Kanebo, Laurier, Merries and Molton Brown, Kao is part of the everyday lives of people in Asia, Oceania, North America and Europe. Combined with its chemical division, which contributes to a wide range of industries, Kao generates about 1,500 billion yen in annual sales. Kao employs about 33,000 people worldwide and has 130 years of history in innovation. Please visit the Kao Group website for updated information.

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