You have more than 40 billion hair-thin capillaries in your body and for the most part their inner workings remain a mystery despite their importance in distributing oxygen to your cells.
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We may soon know a whole lot more about capillaries thanks to the work of a research team from Northwestern University in Evanston, Illinois which developed a new tool that images blood flow through these tiny blood vessels. Using a tool they call spectral contrast optical coherence tomography angiography (or SC-OCTA, if you’d rather not raise your blood pressure) the team was able to get an unprecedented look at blood flowing through capillaries. Their research, published in the journal Light: Science & Applications, could have profound implications for healthcare and our understanding of the human body.
Low Flow, No Flow
Researchers and doctors have long been able to see inside of larger blood vessels using ultrasound. But ultrasound doesn’t work in every instance, such as when there is no blood flowing through a vessel. Having low or no blood flow through a capillary, a mere 5-10 microns in diameter—so small that red blood cells must flow through single file, can lead to poor oxygen circulation leading to everything ranging from a mild headache to heart failure.
“You can have great blood flow through arteries and still have absolutely no blood sending oxygen to tissues if you don’t have the right microvasculature,” said Vadim Backman, who led the study.
SC-OCTA doesn’t need blood to be flowing to get a clear picture. In this way it can help doctors determine what might be causing poor blood flow through a capillary, helping to prevent issues stemming from low oxygen levels. It also doesn’t rely on contrast dyes or harmful radiation but works sort of like ultrasound only using light instead of sound waves. Although SC-OCTA only allows an accurate view 1 millimeter into the body, compared to the several centimeters ultrasound is capable of, it offers an unprecedented look at the body and Backman’s team is working to enable SC-OCTA to see even deeper.
“There has been a progressive push to image smaller and smaller blood vessels and provide more comprehensive, functional information,” Backman said. Detecting minute changes in capillary structure could help provide doctors early insight into developing cancers or cardiovascular disease. It will also help with ongoing research in the field of organoids, the study of how organs respond to and develop diseases.