Light and its interaction with tissue has been utilized for some decades by now in instruments used to study the microcirculation. It is for example possible to study the small frequency shifts, Doppler shifts, that arise when light is scattered by moving red blood cells. That is done in laser Doppler flowmetry, a technique that was developed at the department of biomedical engineering during the 80’s to a large extent. As a spin off from that research, the company Perimed was formed, where I am employed today in addition to my employment at the department. The technique was revolutionary and lead to giant leaps forward in the understanding of the microcirculation. However, its clinical applicability is limited due to lack of detail in information about the blood flow that is delivered from today’s instruments.
My research is focused on using computer models, simulations, and optimization techniques in order to gain much more information from the measured signals and thus produce better blood flow measures. By using that approach, we can for example generate a speed resolved blood flow measure in absolute units, which is easier to interpret for the user and can be used to draw conclusions about flow in different vessel compartments. We have successfully used the concept not only within laser Doppler flowmetry but also within diffuse reflectance spectroscopy, enabling accurate estimation of red blood cell tissue fraction and their oxygen saturation. Those two techniques have been combined into a system that is now sold to clinical researchers by Perimed – the PF 6000 EPOS system (Enhanced Perfusion and Oxygen Saturation).
Until recently, I have foremost focused on point-wise measuring techniques, but that is now broadened to also include imaging techniques for gaining the same information over spatially resolved surfaces. The same model based principles can be applied within laser speckle contrast imaging for blood flow and hyperspectral imaging for tissue oxygen saturation.