Practice question

Magnetic resonance imaging relies on nuclear magnetic resonance of hydrogen nuclei abundant in water and lipids of brain tissue. A strong static magnetic field aligns proton magnetic moments, then radiofrequency pulses transiently tip alignment. As protons relax, they emit signals whose T1 and T2 relaxation times differ between gray matter, white matter, cerebrospinal fluid and pathology, enabling exquisite soft-tissue contrast without ionizing radiation. Computed tomography uses X-ray attenuation, PET uses positron annihilation photons, EEG measures scalp electric fields, none originate from nuclear resonance of protons like MRI.