Blood Flow and Oxygenation

RMD is developing techniques to use Diffuse Reflectance Spectroscopy (DRS), Diffuse Optical Tomography, and Diffuse Correlation Spectroscopy (DCS) to obtain crucial new information about blood flow and tissue oxygenation.

Diffuse Correlation Spectroscopy can be used to determine blood flow rate by monitoring the speckle fluctuations that occur when a coherent laser source illuminates the red blood cells that are flowing through the body.  This technique has a strong signal-to-noise ratio advantage over Laser Doppler, because RMD has the ability to perform single photon counting utilizing our Geiger mode avalanche photodetectors.  DCS has been successfully applied to brain hemodynamics, photodynamic therapy dosimetry and for measuring the depth of burnt tissue. 

Diffuse Reflectance Spectroscopy provides dynamic information about local hemoglobin concentration (Hb) and blood hemoglobin oxygen saturation (SO2).  DRS measures the difference in the absorption characteristics of oxyhemoglobin and deoxyhemoglobin at several wavelengths, which enables us to estimate tissue and blood oxygen saturation levels.  When combined with DCS, we are able to continuously monitor blood flow and pulse rate to determine changes in cardiac output.

Diffuse Optical Tomography takes DRS to the next level by using light scattering and absorbance to create 3D images of the tissue and blood oxygenation beneath the skin.  By using multiple light sources and detectors coupled with diffusion theory algorithms we can understand both the structure of the underlying tissue and its state of oxygenation.

Instruments under Development at RMD

Using DRS, DOT, and DCS, RMD scientists are actively involved in meeting several clinical challenges: