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Axial Oblique CT Image Aligned with the L5-S1 Disc Allows for Visualization and Avoidance of Exiting Nerve Root and Iliac Crest during Discography 2011

General Spine

Thomas, C, Lee, MD
Ajit, Puri, MD, Non ASSR Member
Raymond, Y, Huang, MD/PhD, Non ASSR Member
Charles, H, Cho, MD/MBA, Non ASSR Member

Paper/Non-Mentor

Purpose

Discography by fluoroscopy can be technically challenging to seemingly impossible at some levels, particularly L5-S1 due to the narrow window of access created by the iliac crests and exiting nerve roots. Various methods for improving technical success have been described such as the use of curved needles. In this article we describe a method of performing discography with oblique axial CT to plan a path medial to the exiting nerve with retrospective analysis of whether this method would allow for successful disc access on previously unsuccessful discograms.

Methods & Materials

A three year search for studies containing the words discogram, diskogram, discography, and diskography at our institution was performed after IRB approval. For discograms which were not technically successful, an axial oblique CT image was retrospectively created on the disc that could not be accessed to determine if there were a direct line approach to the disc from the skin surface.

Results

Fourteen successive patients who had undergone discography from June 2009 to October 2010 were identified. Eight of the discograms were not completely technically successful due to failure to access of one of the discs; 7 of these were with fluoroscopic guidance and 1 with CT guidance. Failure was attributed to lack of bony access or radiculopathy due to a nerve root along the needle path. Axial oblique CT image was retrospectively created for all cases except for one for which axial oblique MRI was reformatted since there was no CT available. In all cases, a direct line of approach to the disc in question that avoided the bony structures and exiting nerve roots was possible.

Conclusion

An axial oblique CT image aligned with the disc at the time of discography allows for avoidance of the exiting nerve roots which can not be visualized by fluoroscopy. A future study will prove if the CT guided simultaneous placement of multiple needles at different angles and reduced kV and mAs settings with total radiation lower than a standard CT dose compares favorably with fluoro guided procedure time and radiation.

References/Financial Disclosures

No financial disclosures.

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