The virus is even deceptive at times. As it can prevent brain cavities from properly draining cerebrospinal fluid, you may get the false impression that some fetuses are normal when they're really victims of Zika-related bloat. There's a real risk that the cavities can burst and collapse the brain.

The scans will help make sense of how Zika behaves, and could also help with critical decisions. Parents may learn about a fetus' fate early enough to decide whether or not they want to carry it to term. At the same time, it could offer hope to parents by revealing when a fetus is untouched -- if those early warnings signs don't appear, the family might rest that much easier. Although wider studies are necessary to get the full scope of what's happening (one just started with 10,000 babies), this is an important start.