Which procedure involves injecting dye into the cerebrospinal fluid to outline spinal structures on X-ray?

• A. Lumbar Puncture
• B. Myelography
• C. MRI
• D. PET Scan

Answer: (B)

Myelography uses an intrathecal contrast to visualize the spinal canal on X-ray. In this procedure, a needle is placed into the subarachnoid space (usually via the lower back) and a radiopaque dye is injected. The dye outlines the spinal cord and nerve roots, allowing X-ray (and often CT) images to reveal abnormalities like herniated discs, tumors, or narrowing of the spinal canal. This is different from a lumbar puncture, which is done mainly to sample CSF or administer medications and isn’t aimed at producing X-ray images of the spine with contrast. MRI and PET scans rely on magnetic fields or radioactive tracers and do not involve injecting dye into the CSF to outline spinal structures on X-ray.