Which imaging modality uses a magnetic field and pulses of radio wave energy to make pictures of organs and structures inside the body?

• A. TTP
• B. CT Scan
• C. MRI
• D. Endoscopy

Answer: (C)

Magnetic resonance imaging uses a magnetic field and radiofrequency energy to create pictures of internal structures. The strong field aligns the body's hydrogen protons, and the radiofrequency pulse perturbs them. When the pulse ends, the protons return to alignment and emit signals that are detected and converted into images. Different tissues relax at different rates, giving excellent soft-tissue contrast without using ionizing radiation. This makes MRI especially useful for detailed views of the brain, spinal cord, joints, and many abdominal organs. By comparison, CT relies on X-rays and exposes you to ionizing radiation, endoscopy uses a camera to visualize mucosal surfaces directly, and the remaining term isn’t a standard imaging modality.