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Laser Doppler Imaging

Laser Doppler measures the total local microcirculatory blood perfusion including the perfusion in capillaries (nutritive flow), arterioles, venules and shunting vessels. The technique is based on the emission of a scanning beam of laser light.

Although the scanning motion of the laser beam appears continuous to the eye, each measurement is in reality made up of a number of discrete measurement points. In each point, the laser beam stops for some milliseconds to sample the perfusion in the tissue before moving on to the next site. The maximum number of measurement points is 255x255, which means that more than 65 000 separate tissue sites can be scanned in one image. Generally, it is an advantage to average the perfusion over many points, since each individual point is sensitive to noise and to spatial variations the tissue.

When laser light penetrates the tissue under study it is scattered and partly absorbed. Some of the scattered light returns to the tissure surface, where it is registered by a photo detector inside the instrument. This signal is then processed to extract information about the microcirulatory blood flow. According to the Doppler principle, light particles which hit moving blood cells undergo a change in wavelength/frequency (a Doppler shift), while light particles which encounter static structures return unchanged. The perfusion can be calculated since the magnitude and frequency distribution of the doppler shifted light are directly related to the number and velocity of blood cells but unrelated to their direction of movement.

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Improving quality of life since 1981

Perimed AB, established in 1981, provides instruments, software and expertise to enable assessment of the microcirculation. We utilize laser Doppler, laser speckle (LASCA) and transcutaneous oxygen (tcpO2 or TCOM), to accurately monitor and quantify blood perfusion and tissue oxygenation in real-time. Our modular PeriFlux System 5000 and PeriFlux 6000, the latest generation of our PeriFlux System, are excellent choices for diagnosing Peripheral Arterial Disease (PAD) and Critical Limb Ischemia (CLI) or for assessing wound healing potential in your vascular patients. Our blood perfusion imager PeriCam PSI System allows you to investigate spatial distribution, for example during cortical spreading depression.