Which imaging modality best identifies intracranial or vertebral canal involvement not clearly seen on radiographs?

• A. Nuclear medicine scan
• B. Ultrasound
• C. Plain radiographs
• D. CT or MRI

Answer: (D)

When radiographs don’t clearly reveal pathology within the brain or spinal canal, you need imaging that provides detailed cross-sectional anatomy and good soft-tissue contrast. CT and MRI offer this level of detail far better than plain X-rays. CT delivers fast, high-resolution views of bone and can show canal encroachment or fractures that radiographs miss, while MRI excels at soft tissues, revealing brain tissue, the spinal cord, discs, meninges, edema, inflammation, or neoplasia. Because intracranial and vertebral canal problems often involve soft-tissue structures or subtle changes not visible on X-ray, CT or MRI is the best choice to identify the involvement. Ultrasound is limited by bone and depth, nuclear medicine provides functional info with less precise anatomy, and plain radiographs are 2D and can miss details due to overlap.