Improving photoacoustic imaging of lymphatic dynamics in pigmented mice

Lymphatic dynamics has been potentially linked to a number of diseases. A mouse is a versatile model providing convenient in-vivo and ex-vivo studies of lymphatic drainage by photoacoustic tomography. However, the accuracy of the in-vivo multispectral optoacoustic tomography (MSOT) still requires further improvement to achieve required resolution, in particular in pigmented mice. We studied factors affecting the quantitative accuracy of the spatial mapping and temporal tracking of the novel hybrid photoacoustic-fluorescent contrast agent by MSOT. We found that the best performance among the three methods of spectral deconvolution was by the linear regression. We developed a set of 11 wavelengths which allows for the MSOT tracking of the lymphatic drainage with the temporal resolution of few seconds per image. The coloring effect on the light fluence due to the skin pigmentation was an important factor affecting the quantitative results of the dynamic tracking of lymphatic drainage. We proposed a simple non-linear spectral model accounting for the coloring by skin melanin.