Blood Flowing through a Vessel (image) The Optical Society Caption An in vivo image shows red blood cells within a microvessel. The area occupied by red blood cells in the images can be used to calculate the percent volume of red blood cells, a key measurement for many medical diagnoses. Credit Biomedical Optics Express Usage Restrictions None Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.