Which imaging modality avoids radiation but may require sedation and is often preferred for detailed CNS imaging when feasible?

• A. CT
• B. Ultrasound
• C. MRI
• D. X-ray

Answer: (C)

MRI uses strong magnets and radiofrequency signals to create highly detailed images of brain tissue without ionizing radiation. This is why it avoids radiation exposure, which is especially important in children who may need multiple scans. Its superb soft tissue contrast and ability to image in multiple planes provide excellent detail of CNS structures, making it the preferred choice for thorough CNS evaluation when the child can stay still or when sedation is available to help with stillness. The main trade-off is the longer scan time and the potential need for sedation, as well as possible contraindications (like certain implants). In contrast, CT and X-ray expose the patient to radiation, and ultrasound, while safe and quick, does not reliably visualize detailed CNS structures in older children due to the skull and its limitations for deep brain pathology.