The 70-year-old patient in the Auckland Hospital in New Zealand had suspiciously low blood pressure. The doctors were stumped. But they had an unusual experimental tool at their disposal: a unique computer program that analyzes a magnetic-resonance imaging (MRI) scan, measuring the motion of a patient's heart and comparing it to that of a "healthy" virtual heart constructed not of blood and tissue but from mathematical equations. The analysis handed the clinic's experts the smoking gun: part of the heart was twisting in a pattern often associated with a partially blocked valve, which, untreated, would probably kill the patient within three years.

To diagnose this disorder, surgeons would normally have to crack open the patient's chest. But the software had accurately identified the problem in about 15 minutes. "It helps point out where the heart wall may be failing," says Peter Hunter, the University of Auckland bioengineer whose team developed the software in collaboration with the German company Siemens.