Fig. 1

RSOM imaging work flow and exemplary images of renal vasculature. A Schematic cartoon of the imaging workflow. After cervical dislocation, kidneys were prepared and freshly imaged with the RSOM system. The excised kidney is covered with ultrasound gel and placed under a water bed shielded by a plastic foil. The tissue is illuminated with two 532nm lasers and the generated ultrasound waves are captured by the detector. A pre-scan is conducted before every full scan. Optoacoustic signals are than reconstructed by a dedicated software visualizing mainly haemoglobin molecules and the respective structures filled with it. B Exemplary reconstructed cross-sectional RSOM maximum intensity projections (MIP) of a heterozygotes (HET) 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. All three imaging planes (YX, XZ, and ZY) are displayed with a 2-fold magnification of a central kidney section (Rectangle 2x2mm) with a large and many small vessels. Scale bars indicate 1mm. C Exemplary reconstructed cross-sectional maximum intensity projections (MIP) of a knockout (KO) mouse kidney are displayed. A region of interest (outlined in yellow) was automatically drawn around each kidney. The included area was used for further analyses. HET = heterozygotes (HET), KO = knockout (KO), MIP = maximum intensity projection, ROI = region of interest, MF = merge frequency, LF = low frequency, HF = high frequency, min.= minimum, max.= maximum