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Radiology Studies - Myelogram

Diagnostic Study - Description & Definition

Background

A myelogram is a particular type of radiograph whereby a contrast medium is injected into the cervical or lumbar spine to detect the location of an injury, cysts and tumors. Although myelography has been largely replaced by CT and MRI, in special instances, a myelogram may help to find the cause of pain not found by an MRI or CT.

Historical Overview

The technique of myelography was first described by Sicard and Forestier in 19211; by the end of that decade, it had become an established diagnostic approach.2,3 Although the procedure was elaborate, involving the intrathecal administration of contrast that had to be withdrawn using suction at the end of the procedure, myelography was the only diagnostic method available for decades that could be used to assess soft-tissue injuries and other neurological conditions, such as disc herniation and nerve root compression, which were not visible on conventional x-rays. In the 1970s and 1980s, the introduction of CT and water-soluble contrast agents made the procedure safer, easier to perform and more precise. Myelo-CT was first published by Di Chiro and Schellinger in 19764; it soon became a standard procedure. When MRI became clinical routine, myelography appeared obsolete. However, even today, it is a safe and well-established method for assessing special neurological conditions.5

Description

For safety reasons, even cervical myelography involves lumbar puncture and ascending contrast flow. The patient is prone, and the contrast is injected using fluoroscopy. A picture is taken with the needle in situ, and then the needle is removed. When the contrast has reached the lower part of the cervical spine, the patient is turned onto his/her stomach, and routine views are taken.

Normal Study Findings - Video
Diagnoses Where These Studies May Be Used In Work-Up (with abnormal findings images)
Comments and Pearls
  • In some patients, MRI is not possible owing to safety reasons (eg, pacemaker), imaging quality (eg, metal implants) or other patient limitations (claustrophobia).
  • MRI is not always superior to myelography; nerve root compression is underestimated by MRI in nearly 30% of cases compared with 5–7% with myelography.6
  • Cervical root avulsion requires detailed, high-resolution imaging. In one study, myelography was superior to MRI in delineating the ventral and dorsal rootlets intraoperatively, with 85% accuracy for CT myelography and 58% accuracy for MRI.7
References
  1. Sicard JA, Forestier J. Méthode radiologique d’exploration de la cavité épidurale par le lipiodol. Revista de Neurologia 1921;28:1264-6.
  2. Bonnemain B. L’huile iodee (lipiodol) en radiologie. Les premieres annees d’experience: 1921–1931. Revue d'Histoire de la Pharmacie 2000;88:493-508.
  3. Worth HM. The use of lipiodol in the localisation of spinal tumours. Br J Rheumatol 1938;11:211-26.
  4. Di Chiro G, Schellinger D. Computed tomography of spinal cord after lumbar intrathecal introduction of metrizamide (computer-assisted myelography). Radiology 1976;120:101-4.
  5. Ozdoba C, Gralla J, Rieke A, Binggeli R, Schroth G. Myelography in the Age of MRI: Why We Do It, and How We Do It. Radiol Res Pract 2011;2011:329017. PMC3197073
  6. Bartynski WS, Lin L. Lumbar root compression in the lateral recess: MR imaging, conventional myelography, and CT myelography comparison with surgical confirmation. AJNR Am J Neuroradiol 2003;24:348-60.
  7. Carvalho GA, Nikkhah G, Matthies C, Penkert G, Samii M. Diagnosis of root avulsions in traumatic brachial plexus injuries: value of computerized tomography myelography and magnetic resonance imaging. J Neurosurg 1997;86:69-76.
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