Which imaging modality uses magnetic fields to create images of soft tissues?

Which imaging modality uses magnetic fields to create images of soft tissues?

• A. X-ray
• B. Magnetic resonance imaging
• C. Ultrasound
• D. CT scan

Answer: (B)

This question tests which imaging modality uses magnetic fields to visualize soft tissues. Magnetic resonance imaging achieves this by placing the body in a strong static magnetic field that aligns hydrogen nuclei in water and fat. Radiofrequency pulses perturb this alignment, and as the nuclei relax, they emit signals that are spatially encoded to form detailed images. Because it relies on magnetic properties and does not involve ionizing radiation, MRI provides excellent soft-tissue contrast, making it ideal for viewing brain, spinal cord, muscles, ligaments, and other soft structures. In contrast, X-ray and CT depend on ionizing radiation and tissue density, while ultrasound uses sound waves. Therefore, the method described is MRI.

This question tests which imaging modality uses magnetic fields to visualize soft tissues. Magnetic resonance imaging achieves this by placing the body in a strong static magnetic field that aligns hydrogen nuclei in water and fat. Radiofrequency pulses perturb this alignment, and as the nuclei relax, they emit signals that are spatially encoded to form detailed images. Because it relies on magnetic properties and does not involve ionizing radiation, MRI provides excellent soft-tissue contrast, making it ideal for viewing brain, spinal cord, muscles, ligaments, and other soft structures. In contrast, X-ray and CT depend on ionizing radiation and tissue density, while ultrasound uses sound waves. Therefore, the method described is MRI.