Which imaging modality is most useful for identifying demyelinating plaques in multiple sclerosis?

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

Answer: (B)

MRI is the imaging modality of choice for identifying demyelinating plaques in multiple sclerosis. It has high sensitivity for white matter changes, allowing detection of both old and new lesions. On MRI, T2-weighted and FLAIR sequences reveal hyperintense plaques in characteristic MS locations such as periventricular, juxtacortical, infratentorial regions, and along the spinal cord. Using gadolinium contrast on T1-weighted imaging helps identify active inflammation by showing enhancement where the blood–brain barrier is disrupted, indicating ongoing demyelination. In contrast, CT scans are much less sensitive for MS plaques, especially early or small lesions; ultrasound isn’t used for brain parenchymal lesions, and X-ray provides no information about demyelination. Thus, MRI provides the most comprehensive and sensitive assessment of demyelinating plaques.