Two-Week Brain Tumor Test, Done in Twelve Minutes

The glass slide is nothing special. A sliver of brain tumor, fixed in paraffin, sliced thinner than a hair and washed in the same two dyes pathologists have leaned on for more than a century: hematoxylin to stain the cell nuclei a bruised purple, eosin to wash the rest a dusty pink. Hospitals everywhere make these. A scanner turns one into a digital image, and that image goes to a piece of software called Hetairos. Roughly twelve minutes later, out comes a name, picked from 102 possibilities,...