The 9-year-old lay in a coma, her brain filling with blood. Scans showed a nasty tangle of blood vessels, one of which had burst. Doctors near her New Jersey home were too anxious to operate, fearing that more would go.
By the time she was transported to Boston Children’s Hospital the next day, hospital staff had already printed out a 3-dimensional plastic model of her brain. It showed a thick clump of blood vessels under very high pressure (think of balloons overstuffed with air) and perilously close to her brainstem — the part of the brain that controls breathing and many other essential activities. But it also suggested to Dr. Edward Smith that there was a pathway through for his scalpel.
A few weeks later, Smith and his colleagues commandeered an operating room and ran through the procedure, using several more 3D models for guidance. When they did the real thing a day after that, they already knew the route they needed to take to reroute the patient’s blood vessels and save her life.