In MRI, what is the primary element used for imaging?

The primary element used for imaging in MRI is hydrogen. This is due to the abundance of hydrogen protons in the human body, primarily found in water and fat. When an MRI scanner is used, a strong magnetic field aligns the hydrogen nuclei. The scanner then sends radiofrequency pulses that disturb this alignment, causing the hydrogen protons to emit signals as they relax back to their original state. These signals are then processed to create detailed images of the internal structures of the body.

The effectiveness of hydrogen in MRI is further enhanced by its high sensitivity to magnetic fields due to its nuclear properties, making it an ideal choice for producing high-contrast images. Other elements, like sodium or carbon, have their own unique properties and uses in specialized applications but are not the primary focus of standard MRI imaging due to their lower abundance or less favorable nuclear characteristics for imaging purposes.