"The main component of the MRI system, or scanner, is a magnet. This magnet causes your body's hydrogen atoms to align themselves in such a way as to receive radio signals from the magnetic resonance system. When your body receives these signals, it reacts by sending its own radio signals back to the machine. It is this radio frequency transmitted by your body that is computer-processed and turned into incredibly detailed images."
Hydrogen atoms aligning themselves to pick up radio signals. Perhaps I won't NEED a CD after all--I can just jack the headphones into the socket at the bottom of my skull and listen to NPR while they do the deed.