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CT Myelography: Is There a Role for this Imaging Relic? 2007

General Spine

Lubdha M Shah, M.D.
Christian Morel, M.D., Non ASSR Member
Jonathan Gordon, M.D., PhD, Non ASSR Member

Scientific Poster

Exhibit Panels: 3

Purpose

Purpose: Despite the evolution of MRI as the dominant imaging modality in the evaluation of spine pathology, CT myelography can be a valuable diagnostic tool as an adjunct to MRI or when MRI is contraindicated. This presentation will demonstrate through specific examples the complimentary role of CT myelography.

Methods & Materials

Methods and Materials: Our clinical practice often involves the evaluation spine disease with both myelography/CT myelography and MRI. The Radiology Information System (RIS) was reviewed for cases in which myelography and MRI were performed. Those cases in which CT myelography was particularly essential to the diagnosis are presented to demonstrate the value of this technique.

Results

Results: CT myelography has survived as a diagnostic radiologic test not only due to referring surgeon preferences and when there are contraindications to MRI, but also because it has proven to be quite useful in its role as a complimetary modality. CT myelography maintains an above average ACR appropriateness score in patients with an indeterminate MRI and a history of radiculopathy, spinal surgery with hardware, and cauda equina syndrome. MRI findings in the spine can be equivocal, particularly in patients with postoperative hardware or in the cervical spine; and CT myelography remains an appropriate study to arbitrate in these cases. This is primarily a result of CT myelography being able to determine the relative contribution of disc protrusion, osteophyte, joint hypertrophy, and ligamentum flavum to foraminal or spinal canal compromise. We show an example of this in a patient with a foraminal disc protrusion in the cervical spine, in which the severity of this lesion on the myelogram was initially underestimated on MRI. In our practice, referring spine surgeons find CT myelography an important complimentary study to MRI for pre operative planning. The conventional myelographic portion offers a dynamic evaluation of spinal degenerative disease. Dynamic information of CSF flow in the setting of obstruction or in other pathologies of the thecal sac can be observed; we present a patient with a multiloculated, postoperative seroma versus pseudomenigocele in which it was indeterminate on the MRI whether communication persisted between the thecal sac and the fluid collection, despite previous treatment. The myelogram confirmed the persistent communication between the thecal sac and the pseudomenigocele. The nerve roots in the spinal canal and some spinal cord pathologies can be well delineated on CT myelography as demonstrated by the example of a patient with a split cord syndrome, which was exquisitely delineated on the CT myelography, but was difficult to accurately diagnose on the MRI. The important clinical and technical concerns when performing a myelogram are reviewed, and the systemic evaluation of myelogram are discussed. The complimentary information obtained from this modality in conjunction with MRI is illustrated through various cases.

Conclusion

Conclusions: CT myelography does have role in the diagnosis of spine pathology as it provides complimentary information to MRI and in some cases may be the only available means of evaluation.

References

No disclosures.

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