Using the method of 3D optoacoustic tomography, we studied changes in tissues of the whole body of nude mice as the
changes manifested themselves from live to postmortem. The studies provided the necessary baseline for optoacoustic
imaging of necrotizing tissue, acute and chronic hypoxia, and reperfusion. They also establish a new optoacoustic model
of early postmortem conditions of the whole mouse body. Animals were scanned in a 37°C water bath using a three-dimensional
optoacoustic tomography system previously shown to provide high contrast maps of vasculature and organs
based on changes in the optical absorbance. The scans were performed right before, 5 minutes after, 2 hours and 1 day
after a lethal injection of KCl. The near-infrared laser wavelength of 765 nm was used to evaluate physiological features
of postmortem changes. Our data showed that optoacoustic imaging is well suited for visualization of both live and
postmortem tissues. The images revealed changes of optical properties in mouse organs and tissues. Specifically, we
observed improvements in contrast of the vascular network and organs after the death of the animal. We associated these
with reduced optical scattering, loss of motion artifacts, and blood coagulation.
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