One of the biggest problems with brain cancer treatment is that only a limited amount of chemotherapy drugs make it through. See, our brain's blood vessels are tightly lined with cells to keep out toxins and pathogens. The bad news is that it also hinders medicine from reaching tumors. A team of French scientists have recently tested a promising answer to that issue: an ultrasound implant that they designed to temporarily make this "blood-brain barrier" permeable. They ran a pilot with 15 patients suffering from glioblastoma, an aggressive form of brain cancer, and results showed that their technique successfully allowed more medicine to pass through.