Which type of imaging uses magnetic fields and radio waves?

Magnetic Resonance Imaging (MRI) is the correct choice as it specifically utilizes strong magnetic fields and radio waves to generate detailed images of the organs and tissues within the body. The process involves aligning the nuclear spins of hydrogen atoms in the body using a magnetic field, and then using radiofrequency pulses to disturb this alignment. When the pulses cease, the hydrogen atoms emit signals as they return to their original alignment, which are then captured and transformed into images. This method is non-invasive and provides excellent contrast between different types of soft tissues, making it particularly effective for brain, muscle, and joint imaging.

In contrast, X-ray imaging relies on ionizing radiation to create images by passing X-rays through the body, where denser tissues absorb more radiation than less dense tissues, producing a negative image on film or a digital detector. Computed Tomography (CT) also utilizes X-rays, capturing multiple images from various angles and reconstructing them into cross-sectional views of the body. Ultrasound imaging uses high-frequency sound waves to produce images of structures within the body, relying on the echo of these sound waves as they bounce off tissues, which is different from both MRI and ionizing radiation techniques.