Final answer:
Myelography is an imaging technique that uses a contrast medium to diagnose spinal cord conditions such as internal disk lesions, posttraumatic swelling, and posterior disk herniation.
Step-by-step explanation:
Myelography is a diagnostic exam used to visualize the spinal canal and cord using a radiopaque contrast medium. This medical imaging technique can help in the diagnosis of various conditions affecting the spinal cord and adjacent structures. Myelography is particularly useful in identifying conditions such as internal disk lesions, posttraumatic swelling of the spinal cord, and posterior disk herniation. By injecting contrast dye into the cerebrospinal fluid, myelography provides detailed images that can reveal disruption or compression of the spinal cord and nerves due to these disorders.