The technique allows nanoparticles to group together inside cancerous tumours, creating masses with enough of a magnetic signal to be detectable by a magnetic resonance imaging (MRI) machine. These nanoparticles made of iron oxide are supposed to flow through the bloodstream and enter tumours.

Since solid tumours must form new blood vessels in order to grow and since this growth is so rapid in cancerous tumours, there are gaps in the endothelial cells that line the inside of the blood vessels. The nanoparticles can slip through these gaps to enter the tumours.

Once inside the tumour, the nanoparticles can be triggered to group together by a mechanism designed by the MIT engineers. Specifically, certain enzymes, or proteases, inside the tumours cause the nanoparticles to "self-assemble" or stick together. The resulting nanoparticle clumps are too big to get back out of the gaps. Further, the clumps have a stronger magnetic signal than do individual nanoparticles, allowing detection by MRI.

The technique initially is being used to study breast tumours. Bhatia added that it eventually may be applied to many different types of cancers and to study the "triggers" that turn a benign mass in the body into a cancerous tumour. Nanoparticles also hold the promise of carrying medicines that could kill cancer cells, replacing radiation or chemotherapy treatments that cause negative side effects such as hair loss or nausea.; Source: Massachusetts Institute of Technology