Press PLAY button to start video. This x-ray computed tomography (CT) scan was made under liquid nitrogen (-196°C) at the end of the cryopreservation process. The colors are believed to measure the degree of success in avoiding ice formation as follows:
Orange: Complete prevention of ice formation (vitrification) as a result of achieving more than 100% of target cryoprotectant concentration in tissue.
Light Purple: Complete prevention of ice formation (vitrification) as a result of achieving 80% to 100% of target cryoprotectant concentration in tissue.
Green: Partial freezing due to achieving 40% to 70% of the target concentration of cryoprotectant.
Red: Extensive freezing due to achieving 10% to 30% of target concentration of cryoprotectant. Due to iron content, red can also be the color of blood frozen without any cryoprotectant.
Grey: Maximum freezing of brain tissue without any cryoprotectant, or freezing of water with minimal cryoprotectant.
Cyan: Frozen water without any cryoprotectant.
Circles on the right side of the image are scans of pure cryoprotectant solution at the indicated concentrations expressed as a percentage of desired target concentration.
Note: In cases with low ischemic time, an intact blood-brain barrier may result in contraction of the brain due to dehydration during cryoprotectant perfusion. Pooled and solidified cryoprotectant may also be present against the superior interior surface of the cranium, which is inverted during cooling.