Fig. 5

Multispectral raster scanning optoacoustic mesoscopy imaging. A Exemplary reconstructed cross-sectional msRSOM maximum intensity projections (MIP) of a wildtype mouse kidney are displayed. Merged frequencies (red-green) combine the information from low frequencies (bigger vessels = red) and higher frequencies (smaller vessels = green) allowing visualization of renal vasculature similar to images from RSOM (Figs. 1 and 3) at the same SWL of 532nm. Scale bars indicate 1mm. B Exemplary reconstructed cross-sectional msRSOM maximum intensity projection (MIP) of spectrally unmixed msRSOM parameters (blue=HbR and red=HbO₂) from four wavelengths (532, 555, 579, 606nm). HbR indicating deoxygenated - venous and HbO₂ indicating oxygenated–arterial blood in the freshly excised and halved kidney. Scale bars indicate 1mm. C The same image as shown in B coded for vessel orientation by an image processing software. Orientation of the vessels from the kidney hilus to the periphery is visualized confirming normal anatomical distribution and orientation. Scale bars indicate 1mm. D A histological section of the kidney shown in A–C. PAS staining confirms the anatomical distribution and orientation of kidney tissue and vessel orientation. A 5-fold magnification of a central kidney section (rectangle 2x2mm) is shown. Scale bars indicate 1mm and 0.2mm in the magnification. LF=low frequency, HF=high frequency, MF=merge frequency, HbO₂=oxygenated hemoglobin, HbR=deoxygenated hemoglobin, WT=wildtype, PAS=period acid-Schiff’s, min.=minimum, max.=maximum