Myelography
X-ray examination of the central nervous system in the spinal canal, the sub-arachnoid space. Contrast medium is injected into the sub-arachnoid space, by inserting an injection needle between 2 vertebra and through the dura and arachnoidea. The dura will offer some resistance, but when the point of the needle is inside the sub-arachnoid space CSF will trickle out. 10-20 ml of contrast medium is injected slowly, replacing and gradually mixing with the CSF. On the X-ray picture the CSF will be bright because of the contrast medium, and the spinal cord and nerves branching off the spine will appear as darker shadows, the nerves having a slight feathery look. Filling defects may indicate pathology, either a narrowed spinal canal, a tumour taking up place or a slipped intervertebral disc.
GE Healthcare Glossary