Human: I'd like to learn more about the different types of MRIs. Assistant: 
There are several different types of MRI machines, each with a slightly different purpose and technology. The most common type is the magnetic resonance imaging (MRI) machine, which uses strong magnetic fields to align the protons in hydrogen atoms in order to produce images of organs and tissues within the body. Other types of MRI machines include functional magnetic resonance imaging (fMRI), diffusion tensor imaging (DTI), and magnetic resonance spectroscopy (MRS). Each type of MRI machine has its own advantages and disadvantages, so it's important to consider your needs before deciding on one.