Magnetic particle imaging (MPI) is a way of using magnets to find small particles in our bodies. It works like this: first, tiny particles that contain metal (called "magnetic nanoparticles") are injected into our bodies. Then, powerful magnets create a strong magnetic field around us. This magnetic field makes the particles move in different directions.
A special camera called an MPI scanner is used to detect the movement of the particles. The scanner sends out little bursts of energy in the shape of a wave. As the particles move around in the magnetic field, the wave is disrupted. The scanner can read this disruption. It then uses this information to create a map of where the particles are in our bodies. This map can help doctors to find things in your body that cannot be seen with other kinds of scanning technology.