Which imaging modality uses magnetic fields, radiofrequency pulses and a computer to generate cross-sectional slices?

• A. MRI
• B. CT
• C. Attenuation
• D. Spatial resolution

Answer: (A)

Magnetic resonance imaging uses magnetic fields, radiofrequency pulses, and a computer to generate cross-sectional slices. The strong magnetic field aligns hydrogen nuclei in the body, radiofrequency pulses perturb that alignment, and the emitted signals are processed by a computer to reconstruct images in different planes. This combination provides detailed soft-tissue contrast without ionizing radiation. The other terms are not imaging modalities: CT uses X-ray attenuation to form images, while attenuation and spatial resolution describe image properties or measurement concepts rather than a modality.