MRI utilizes strong magnetic fields and non-ionizing radiation in the radio frequency range,and according to current medical knowledge, is harmless to patients. Another advantage of MRI is that soft tissue contrast is much better than with X-rays leading
to higher-quality images, especially in brain and spinal cord scans. See Figure
3.2(c). Refinements have been developed such as functional MRI (fMRI) that measures
temporal variations (e.g., for detection of neural activity), and diffusion MRI
that measures the diffusion of water molecules in anisotropic tissues such as white
matter in the brain.